Associated LAH Numbers,Factorial Series Distributions and Unbiased Estimation of a Size Parameter

A finite population consists of kN individuals of N different categories with k individuals each. It is required to estimate the unknown parameter N, the number of different classes in the population. A sequential sampling scheme is considered in which individuals are sampled until a preassigned number of repetitions of already observed categories occur in the sample. Corresponding fixed sample size schemes were considered by Charalambides (1981). The sequential sampling scheme has the advantage of always allowing unbiased estimation of the size parameter N. It is shown that relative to Charalambides' fixed sample size scheme only minor adjustments are required to account for the sequential scheme. In particular, MVU estimators of parametric functions are expressible in terms of the C-numbers introduced by Charalambides.     

Comparison of Resubstitution,Data Splitting,the Bootstrap,and the Jackknife as Methods for Estimating Validity Indices of New Marker Tests: A Monte Carlo Study

Estimating the diagnostic efficiency of marker tests on the basis of the training set is an intricate problem of discriminant analysis for which no analytical solution exists. The paper outline the problem, describes various popular estimation procedures and presents the results of computer simulations comparing the estimators with respect to both bias and variance.     

Asymptotic Expansions and Estimation of the Expected Error Rate for Equal-Mean Discrimination with Uniform Covariance Structure

The asymptotic error rate of the equal-mean, uniform-covariance-matrix classification rule is approximated by a first order asymptotic expansion. The approximation is compared for accuracy with a Monte Carlo simulation. Finally, an estimator of the error rate and an estimator of the variance of the error rate estimator are derived and applied to a classical example.     

Estimation of N-amino-N,N-dimethylaminoethanol, choline and their acetate esters by gas chromatography mass spectrometry

A method is described for measurement of choline, N-aminodeanol, and their acetyl esters by gas chromatography mass spectrometry. The preparation of N-aminodeanol and its isotopic variants is also described. This method allows a thorough quantitative analysis of the replacement of true with false neurotransmitter in biological preparations.     

Comparison of ultrafiltration units for proteomic and N-glycoproteomic analysis by the filter-aided sample preparation method

The precision with which the dissociation constant, K_D, can be obtained from isothermal titration calorimetry depends on, among other factors, the concentrations of the interacting species. The so-called c value—the ratio of analyte concentration to K_D—should fall in the range of 1 to 1000 for reliable K_D determination. On the basis of simulated, noise-free data, Biswas and Tsodikov [5] recently suggested an optimal c value of 5 to 20. By contrast, we find an optimum at c > 40 on determining the K_D confidence intervals through simulations containing noise levels typical of state-of-the-art microcalorimeters.     

Measurement of pO2 by luminescence lifetime spectroscopy: A comparative study of the phototoxicity and sensitivity of [Ru(Phen)3]2+ and PdTCPP in vivo

Dysfunctions in tissue metabolism can be detected at early stages by oxygen partial pressure (pO₂) measurement. The measurement of emission lifetimes offers very promising and non‐invasive approach to estimate pO₂ in vivo. This study compares two extensively used oxygen sensors and assesses their in vivo oxygen sensitivity and phototoxic effect. Luminescence lifetime of Ru‐polypyridyl complex and of Pd‐porphyrin is measured in the Chick's Chorioallantoic Membrane (CAM) model with a dedicated optical fiber‐based, time‐resolved spectrometer. The Pd‐porphyrin luminescence lifetimes measured in the CAM model exposed to different pO₂ levels are longer and have a broader dynamic range (10–100 μs) than those of Ru‐polypyridyl complex (0.6–1 μs). The combined statistical analysis based on an estimate of the kurtosis and skewness, bootstrapping method and routine normality tests is performed. The indicators of the averages and signal to noise ratio stability are also calculated. The combination of several data processing allows selection of the better sensor for a given application. In particular, it is found that the advantage of Ru‐polypyridyl complex over Pd‐porphyrin is two‐fold: i) Ru‐polypyridyl complex datasets have consistently better statistical characteristics, ii) Ru‐polypyridyl exhibits lower cytotoxicity.

     

Assessing Variability by Joint Sampling of Alignments and Mutation Rates

When two sequences are aligned with a single set of alignment parameters, or when mutation parameters are estimated on the basis of a single ``optimal' sequence alignment, the variability of both the alignment and the estimated parameters can be seriously underestimated. To obtain a more realistic impression of the actual uncertainty, we propose sampling sequence alignments and mutation parameters simultaneously from their joint posterior distribution given the two original sequences. We illustrate our method with human and orangutan sequences from the hyper variable region I and with gene–pseudogene pairs. Received: 16 November 2000 / Accepted: 15 May 2001