bluuebunny/crossref_metadata_2025 huggingface dataset:
Application of Covariance Analysis to Ophtalmologic Research
Authors: Wernecke K.‐D. , Ulrich W. D.
Published: April 2007

Using covariance analysis as an adjusted regression analysis it is possible, with the assumption of homogeneity and normality of variance, to test several regression functions for homogeneity, if the given groups of data material are independent.

This well‐known analysis is applied to a number of examination methods of ophthalmology. In the cases of ophthalmo‐dynamography (ODG) and ophthalmo‐dynamometry (ODM), the paper answers the question to what extent the result of ophthalmologic measurement is influenced by posture (sitting — lying — standing).

Contrary to several authors' practice of combining the regression lines for the systolic and diastolic blood‐pressure because of the improvement of the correlation coefficient to be achieved in this way, it was possible to show that generally such an approach is not recommendable.

Patients suffering from a certain type of arteriosclerosis distinguish themselves by deviations of their ODG data from the normal blood‐pressure relation of the arteria carotis interna and the arteria brachialis. These differences can be tested for statistical significance by means of covariance analysis.
Distribution of the Sum of Independent Zero‐Truncated Linear Function POISSON Random Variables
Authors: Janardan K. G.
Published: April 2007

In this note, the distribution of the sum of independent zero‐truncated linear function POISSON random variables is obtained. This distribution conforms, in special cases, to CACOULLOS (1972) and TATE and GOEN (1958). The distribution of the sum of zero‐truncated BOREL‐TANNER type variables is obtained as a special case.
Quasi Competition — a New Aspect
Authors: BÜHler W. J.
Published: April 2007

The model of quasi competition put forward in 1967 is reinvestigated under the aspect that only large (N →∞) populations are considered. Under this new angle the conclusion that myomas develop from single cells seems better justified than the original discussion indicated.
On Adequateness of Regression Setups
Authors: Bandemer H. , NÄTher W.
Published: April 2007

For the notion of adequateness, which is used in applications in different meanings mostly without definition, we formulate some graduations on the basis of approximation considerations. Furthermore certain consequences are referred for the treatment of estimation and test problems in regression models.
On the Asymptotic Behaviour of the Population Number
Authors: Karev G. P. , Treskov S. A.
Published: April 2007

We consider the stochastic model of an asexual population in which the number of couples formed in some generation is random variable depending on the number of individuals in that generation only. The conditions of convergence were obtained almost everywhere and in mean square of the normalized number of individuals in the n‐th generation. These results may be considered as the generalization of some known statements about the models constructed on the basis of the branching processses theory.
Selection Problems in Balanced Block Designs
Authors: Rasch D.
Published: April 2007

If we have independent random variables the solution of BECHHOFER's selection problem in special cases is easily applied because we can use tables of a standardized multivariate normal distribution. The aim of this note is to show how such tables are also applicable in a case of correlated random variables like the estimates of treatment effects in BIB and BCB. Formulae for a choice of minimal sample sizes are also given.
The Design and Analysis of Experiments with Grouped Measurements. II. Comparison of Means
Authors: HerrendÖRfer G.
Published: April 2007

The method of grouped measurements, described in part one of this article, is worked out for some important comparisons of means. Methods for design of experiments for the multiple t‐Test are given. Two approximate solutions are proposed. An extensive table facilitate to find out the approximate optimal design in the set of designs with preliminated precision.
Estimation and Test for the Mean in a Model II of the Analysis of Variance
Authors: HerrendÖRfer G. , Schmidt J.
Published: April 2007

A sample (y11, …, yin1…, ya1,…,yana) may be given. For yij the model II of a hierarchical analysis of variance may be true. For description of precision α and d2(expectation of the square of the half length of the confidence interval) are used. A procedure for determining an optimal (linear cost of sampling) design in theset of designs with given precision is presented. For the test H0: μ≦ μ0 against HA: μ> μ0 on the same way the optimal design of an experiment is worked out.
On a Basic Assumption in the Line Transect Method
Authors: Sen A. R. , Smith G. E. J. , Butler G.
Published: April 2007

This paper deals with one of the basic assumptions made in estimating population density by the line transect sampling method. Theory has been developed in this paper for estimating, density using a gamma distribution. The results have been applied to data on ruffed grouse.
Estimation of the Distribution of a Genetically Determined Enzyme Polymorphism by a Stochastical Outside Criterion
Authors: Hommel G.
Published: April 2007

The remaining cholinesterase activity after incubation with paraoxon (as an indicator of the activity of human serumparaoxonase) shows a distribution with three clusters which could be explained, after an investigation of families, by a simple two‐allele‐model. A Stochastical outside criterion is given by the constellations of the values within the families.

By modification of an iteration method described by FANGMEYER (1964) it is possible to estimate the distributions and frequencies of the three groups. A simulation study shows that the combination of the used method with the pure cluster analysis is advantageous.
Some Properties of Block Matrices of Models Based on Hierarchical and Crossed Classifications
Authors: Oktaba W.
Published: April 2007

Proofs of several theorems on some properties of block matrices of linear statistical models based on hierarchical and crossed classifications are given. These properties are useful to deduce the estimator of vector of missing data in the case of any hierarchical classification and cross classification with the interaction of the highest order.
A New Algorithm for Explicit Determination of Variance Component Estimations in Mixed Models and Mixed Classifications of Balanced ANOVA
Authors: Holomek D.
Published: April 2007

This paper deals with the balanced case of the analysis of variance. The use of a classification function leads to an easy determination of all possible sources of variation of any mixed classification. For mixed models a new method is derived, which allows to represent explicit the ANOVA‐estimations of the variance components respectively the estimation of the mean sum of squares of the fixed effects for all sources of variation. Thereby the correspondingF‐quotients and the approximate confidence intervals of variance components are received in a simple way.
Hierarchical Classification I: Single‐Linkage Method
Authors: Kopp B.
Published: April 2007

This is the first part of a survey of hierarchical clustering algorithms using joining methods: the Single‐Linkage algorithm. Complete‐Linkage and general algorithms defined by d(Ai, B) = = α,d(Ai, Ar)±αsd(Ai, As)±βd(Ar, As) will be discussed in two subsequent papers.
Algebraic Methods in Evolutionary Genetics
Authors: LjubiČ JU. I.
Published: April 2007

This paper is a survey of some results obtained in evolutionary genetics by algebraical methods. The main topics: 1. Some special classes of algebras which arising in population genetics (stochastic, baric, BERNSTEINian, genetic etc.). 2. The BERNSTEIN'S problem and the stationary genetic structure. 3. The convergence to an equilibrium, the rate of convergence. 4. The exact linearization of evolutionary equation. 5. The exact formulae for evolutionary spectrum and for solution of the evolutionary equation.
MINQUE and ANOVA Estimator for One‐way Classification ‐ a Risk Comparison
Authors: Ahrens H.
Published: April 2007

For the one‐way classification in unbalanced case MINQUEstimator for components of variance are given in a more explicit form than it is done in the paper from C. R. RAO (1971). By means of the risk functions we compare MINQUE and ANOVA estimator. For given nj‐patterns angular ranges in the positive quadrant are given where MINQUE is better than ANOVA estimator. A special nj‐pattern and one parameter δ0 is found for which MINQUE is uniformly better than ANOVA. Limit values are given for MINQUE for δ0 = ∞ and δ0 = 0 and their relations to the ANOVA estimator are considered. The coincidence between MINQUE and ANOVA for balanced case is verified. Extensive numerical studies for real data are carried out which stimulated the search for a fixpoint δ as a point for which the distance to the initial parameter δ0 is as small as possible.
Eine neue Interpretation des HELLMICHschen Maßes K und seine Anwendungen
Authors: Börzsönyi L.
Published: April 2007

From the examination of the properties of symmetry of the correlation functions it appears that the asymmetrical functions contain information capability to be used with advantage for the characterization of causal effects. The paper describes a new interpretation of the K measure of HELLMICH as well as its application in the field of investigation of connections. Computer calculations carried out on plant and human populations justify the use of the introduced measure. Concrete results are presented with respect to two maize diseases “stalk rot” and “ear rot”; further a completely analogous problem to examine the relation between diabetes and high blood pressure is outlined.

Finally some remarks are made on further investigation of measuring numbers and application in a broader sense.
A Two Sample CRAMÉR‐VON MISES Test for Randomly Censored Data
Authors: Koziol J. A.
Published: April 2007

A CRAMÉR‐VON MISES type statistic is introduced for testing the equality of the underlying survival distributions of two populations when observations are subject to arbitrary right censorship. The statistic is appropriate in testing problems where a two‐sided alternative is of interest. The asymptotic distribution of the statistic is found; under certain circumstances, the limiting distribution coincides with that of a one sample CRAMÉR‐VON MISES type statistic for randomly censored data investigated previously. Approximations to the asymptotic distribution are discussed; an example is given.
A Mathematical Model for Extrachromosomal Heredity
Authors: Hoppenmüller W.
Published: April 2007

During embryogeny the components of the cytoplasm of a zygote are subject to certain irregularities. This has been investigated with the aid of some probability models and distribution functions. For mitochondria, which are the most important cell components with respect to extra‐chromosomal heredity, a four‐phase model with computer programs was developed.

The complete arithmetical results total 15,000 pages from a fast printer. For the jobs a CPU‐time of 500 hours, using a SIEMENS 4004 system, was required.
Characterization of the WEIBULL Distribution by Properties of Order Statistics
Authors: Janardan K. G. , Taneja V. S.
Published: April 2007

Let X1:n, X2:n, X3:n…, Xn:n be the order statistics of n independent random variables with the common (absolutely continuous strictly increasing) distribution function F. The main results given in this article are:

For any fixed r and two distinct numbers s1 and s2 (1<r<s1<s2≦n) the distributions of Vi and Wi (defined in (1.11) and (1.12) are identical for i = 1,2 iff F(x) is WEIBULL (1.2).

The statistics D1 and D2 (as in (1.8) and (1.9)) are independent iff F(x) is WEIBULL (1.2).

The statistics Ui (1≦j≦n−1) and Xi:n (i ≦ j) are independent iff F(x) is WEIBULL (1.2).

Let X, X1, X2, …, Xk be random variables such that
magnified image

These conditions are necessary and sufficient for F(x) to be WEIBULL.
On Analysis of Some Augmented Block Designs
Authors: Singh M. , Dey A.
Published: April 2007

Augmented designs are frequently used in practice. In this paper, a simplified procedure of analysis of some types of augmented designs is discussed using the concept of efficiency‐balance and partially efficiency‐balance.
An Unbalanced Mixed Model with Random Effects Having Unequal Variances
Authors: Hussein M. , Milliken G. A.
Published: April 2007

Consider the mixed model where xijk's are known constants, βk are unknown parameters and ai, eij are random variables independently and normally distributed with zero means and variances σdi and σ2 respectively, where it is assumed that the di's are known (di >0). This paper presents procedures for estimating the variance components σ, σ2, for testing the hypothesis σ = 0, and for making transformations to random variables with uncorrelated errors and constant variances in order to estimate as well as to test hypothesis concerning the βk's in the model.
The Heritability of Difference Scores when Environments are Correlated
Authors: Weiss V.
Published: April 2007

The statistical analysis of difference scores (contrasts) is a fundamental problem in all learning, feeding, and training experiments and tests, and in longitudinal studies of growth and development. Outgoing from the analogy between the mathematical models of classical psychological test theory and quantitative genetics, as well as between the parameters reliability and heritability of these models, the present paper derives the formulas of the heritability of difference scores in general cases where it is not assumed that environmental deviations on distinct tests and measurements are uncorrelated. Contrary to the assertion, made by FELDMAN and LEWONTIN, heritabilities in the broad sense can be used as ideal weighting factors in long‐range personnel index selection. Longitudinal studies of twins and the cotwin method are powerful experimental designs to estimate heritabilities of differences.
Statistical Analysis of Joint Effects of Major Genes and Polygenes in Quantitative Genetics
Authors: Tan W. Y. , D'Angelo H.
Published: April 2007

In this paper we analyze a quantitative genetic character which is controlled by both major genes and polygenes. Assuming that there are no epistatic effects, no linkage and no genetic‐environmental interactions, we follow TAN and CHANG (1972) to derive the probability distributions for segregating populations. The numbers of major genes and polygenes, and the additive and dominance effects of major genes and polygenes are then estimated by using the procedures developed in TAN and CHANG (1972) and the POWELL‐FLETCHER search procedure for maximum values. In this paper, we consider the case involving data from P1, P2, F2, B1 (Backcross to P1) and B2 (Backcross to P2) as this type of experiment is common in practical applications. The analyses are applied to a simulated model generated by using binomial, multinomial and normal variables and to the data of an experiment on kernel weight of sorghum plant provided to the authors by Professor GEORGE H. L. LIANG of Kansas State University. The analysis of these data indicate clearly that the method derived in this paper is useful and desirable.
On the Effects of Departure from Normality on theF‐Ratios in a Nested Random Effect Model by Mixture of Normals
Authors: Tan W. Y. , Wong S. P.
Published: April 2007

In this paper we consider the following nested random effect modelmagnified imagewhere the αi's, the βij's and theeijkare independent random variables. By assuming that these variables follow a mixture of two normal densities, we study the effects of departure from normality on the classical JT‐tests for variance components. It is shown that the departure from normality has little effects on the type 1 error and the power function; this indicates that the classicalF‐tests are quite robust with respect to departure from normality.
Some inequalities for the expectation of a product of functions of a random variable and for the multivariate distribution function at a random point
Authors: Horn M.
Published: April 2007

Under certain assumptions the expectation of a product of functions of a random variable is greater (smaller) than the product of expectations. The multivariate distribution function of m independent random variables at a random point is greater than the product of the distribution functions of the m variables.
Quadratische Optimierung für Mixturen
Authors: Recknagel R.‐D.
Published: April 2007

An optimization‐method for quadratic mixture‐polynomials is developed on the basis of a homogeneous model. The described numerical procedure allows to compute the global maximum (or minimum) over a simplex‐shaped region.
Regarding the Optimality of the Formula \documentclass{article}\pagestyle{empty}\begin{document}$ \frac{{n_0 }}{n} = \sqrt p $\end{document} for the Ratio of Sample Sizes of a Control and of p Treated Groups
Authors: Horn M.
Published: April 2007

FINNEY (1955) recommended without argument the ratio \documentclass{article}\pagestyle{empty}\begin{document}$ \frac{{n_0 }}{n} = \sqrt p $\end{document} where p is the number of treated groups to be compared with a control and n and n0 are the sizes of the treated samples and of the control. The question is does this allocation result in an optimum, anywise. RASCH, HERRRENDörfer und BOCK (1972) asserted that this ratio with t‐tests is followed by maximal expected values of the t‐statistics. Here is shown that this allocation with t‐tests provides minimal comparisonwise type II error rates. Moreover, with the t‐test and the DUNNETT test the mean number of type II errors becomes a minimum. Nearly optimal is this allocation with the t‐test and the DUNNETT test regarding the experimentwise type II error rates. Not optimal is this allocation regarding the experimentwise type I error rates.
Estimation of BAYESian Confidence Intervals for the Product of Conditional Survival Probabilities
Authors: Schmitz H.
Published: April 2007

A model is derived to estimate the survival probability of a time interval when censorings occur. The time interval is divided into partial intervals in order to obtain the conditional survival probabilities, each of which is a parameter of a Binomial distributed random variable. To allow for the dependence between the events in the different intervals these parameters are transformed. Corresponding a priori density functions are formulated regarding both the Bayesian uniform distribution and the special model. The a posteriori density function is derived for the product of the conditional survival probabilities, and formulae for the BAYEsian confidence interval and the expectation are given. Lower and upper bounds for the confidence interval and the expectation are derived. Some examples are given to compare the results with other methods.
The Influence of External Real and White Noise on the LOTKA‐VOLTERRA Model
Authors: Arnold L. , Horsthemke W. , Stucki J. W.
Published: April 2007

The behaviour of a marginally stable predator‐prey system, the LOTKA‐VOLTERRA model is analyzed under the influence of parameter fluctuations. The cases of white and real noise are studied separately. It is shown that for white noise no stationary solution exists, but even for time tending to infinity explosion occurs only with zero probability. In the case of real noise the class of noise processes that permit a stationary solution is characterized by their spectral density. It turns out that this class consists of all stationary processes that do not contain the eigenfrequencies of the LOTKA‐VOLTERRA system.

It is shown that for all other real noise processes a resonance phenomenon occurs and the solutions grow unboundedly.
Estimation of Interplant Dependence in a Linear Planting Scheme
Authors: Gleeson A. C. , McGilchrist C. A.
Published: April 2007

A maximum likelihood procedure is developed to estimate the dependence relations between plants at equal distances along a row, by fitting simultaneous bilateral models to the observations. Where there is more than one characteristic measured on each plant, a simultaneous bilateral vector model can be fitted by maximum likelihood procedures. The latter model also applies when one characteristic is measured on each plant in a two‐dimensional planting array where interplant distances within each row are equal but interrow spacing varies. The estimation is particularly suited to the small sample situation.
The Non‐Central Negative Binomial Distribution
Authors: Ong S. H. , Lee P. A.
Published: April 2007

The non‐central negative binomial distribution is derived by mixing the POISSONdistribution with a certain BESSELfunction distribution, or the negative binomial distribution with the POISSONdistribution. Some properties of the distribution are discussed, including a characterization. The fitting of the distribution to some data are given together with the efficiency for various procedures of estimation.
Besetzungsmodelle
Authors: Herrmann H.
Published: April 2007

Starting with the classical occupancy with boxes, balls and probabilities for occupying boxes, we employ new models: a ball, which met a box, occupies this box with a probability depending on the size of box content, and ‐ using several kinds of balls ‐ by the composition of the content too. For that purpose several models are constructed with distinctive forms of the conditions.

Dealing with these models ‐ they are special MARKOvian chains ‐ we pay attention mainly to the so called first passage time Tz for defined events Z; in particular for certain events Z we have to prove that Tz is a random variable, and have to set up the appropriate probability generating function.
Discrimination with a Mixture Population
Authors: Saxena A. K.
Published: April 2007

The regions of classification when one of the populations is a mixture of two or more multivariate normal populations are found to be defined by the functions of the linear discriminant functions used for discriminating between the components of the mixture population and the other multivariate normal population.
A Multivariate Analysis of Hybridization when Covariance Matrices are Unequal
Authors: Misra R. K.
Published: April 2007

Numerous occurrences of natural hybridization have been known in many groups of animals. It has a bearing on growth, nomenclature, speciation, genetics and wildlife management. It is well recognised that demonstration of intermediacy based on several characters makes the identification of hybrids more certain than that based on just a single character, and that differences among the hybrids and the parental populations should be analysed for variations due to the additive genetic (A) and the non‐additive genetic (NA) factors separately. In the present paper (i) it is pointed out that sometimes the assumption that covariance matrices of the hybrids and the parental populations are equal, may not be valid, and (ii) a multivariate method of testing hypotheses analysing differences between the hybrids and the parents, qualified by the A and the NA factors, when covariance matrices are not equal, is submitted.
Use of p‐auxiliary Variates in PPS Sampling
Authors: Agarwal S. K. , Singh M. , Goel B. B. P. S.
Published: April 2007

Present study deals with the use of multivariate auxiliary information in selecting the samples in pps sampling.
Note on Simply Calculating Chi‐square for a r × c‐Contingency Table
Authors: McDonald‐Schlichting U.
Published: April 2007

For evaluating r × c‐contingency tables by χ2, a row components formula is proposed which allows calculating χ2 less tediously than with the general χ2‐formula.
Robuste schätzungen: Ein anwendungsorientierter Überblick
Authors: Hampel F.
Published: April 2007

The paper offers an introductory survey of the area of robust estimation for applied statisticians, without demanding much mathematics. At first, the most important basic ideas of the robustness theory are explained using an example from the analysis of variance. Then the general reasons for and limits of the “robustification” of statistics are delineated. In particular, the various types of deviations from ideal models, such as gross errors, are discussed and their consequences are pointed out. The next part describes several simple robust estimators and their properties, ending with an outlook on robust estimators in linear models. As an appendix a number of frequent objections to and misunderstandings of robustness theory are discussed, refuted and clarified.
A necessary condition for balance of a block design
Authors: Baksalary J. K. , Dobek A. , Kala R.
Published: April 2007

It is shown that, barring orthogonal designs, a necessary condition for a block design,BD(v, b, N), to beJ‐balanced is that the rows of its incidence matrix,N, are linearly independent. This strengthens the conditionb vknown in the literature as FISHER'S inequality.V‐balanced block designs are also discussed.
Improved estimation of potency in slope ratio assays
Authors: Srivastava V. K. , Bhattacharya B. N. , Kumar K.
Published: April 2007

Regression coefficients are regarded as stochastic variables in order to account for this kind of variability. This is needed, because differences in responses at successive doses vary generally and thus the assumption of constancy of regression coefficients is violated.
Asymptotic and explicit formulae for a non‐markovian model with linear transition rule
Authors: Ismail M. E. H. , Theodorescu R.
Published: April 2007

Asymptotic and explicit formulae are obtained for the n‐step stochastic kernel of a special class of non‐MARKOVIAN models with linear transition rule which occur in learning theory, adaption theory, control theory, and biological research.
On a property of the exponential distribution
Authors: Kabe D. G.
Published: April 2007

If t is an independent exponentially distributed random variable, the distribution p = [t ‐ x] is a modified geometric distribution, similar to the result of HAWKINS and KOTZ (1976), x is uniform.
On probability limits in snowball sampling
Authors: Agarwal S. K. , Srivastava A. K.
Published: April 2007

The limits on probabilities under which usual sampling model is to be preferred over binomial sampling model have been worked out.
Tests of significance for point‐biserial rank correlation coefficients in the presence of ties
Authors: Buck W.
Published: April 2007

This paper deals with exact and asymptotic tests of significance of the point‐biserial rank correlations of the KENDALL and SPEARMAN tests when ties are present and mid‐ranks are assigned to tied values.
Simplified formulas for three‐way chi‐square testing
Authors: Lienert G. A. , Wolfrum Christine
Published: April 2007

In order to test against contingency in a 3‐way table, simplified X2‐formulas are given for (1) the general r xcxl‐table, (2) for the rxcx2‐table, (3) for the 2x2xl‐table, and (4) for the 2×2×2‐table. The tests are valid only if a sample of N individuals is observed as to 3 discrete or discretisized (dichotomized) variables which are, under H0, assumed to be totally independent.
Confidence limits for drug‐induced response rates in carcinogenesis experiments
Authors: Wahrendorf J. , Port R. E.
Published: April 2007

Animal experiments in chemical carcinogenesis are often analysed by tests for equal proportions in a 2 × 2 table. Since hereby nothing is said about the power of the tests, we propose to describe the outcome of such an experiment by an upper confidence limit of an adjusted difference between the two response rates.
On the difference between gauss‐markov and least squares estimates
Authors: Scobey P. , Kabe D. G.
Published: April 2007

For the usual full rank univariate least squares regression model y = XB + e, E(e) = 0, E(ee) = A, the equality of the estimates occurs when B‐B* = (XA−1X)−1XA‐1y‐(XX)−1Xy = 0. A necessary and sufficient condition for this equality is that A has some N ‐ k + 1 roots equal where N is the rank of A and k is the rank of X.
Designs for restricted exploration in mixture experiments
Authors: Goel B. S.
Published: April 2007

Extreme Vertices designs were developed by MCLEAN and ANDERSON (1966) for situations where components of a mixture are restricted by lower and upper bounds, SNEE and MARQUARDT (1974) and SNEE (1975) gave algorithms to construct optimum designs in these situations. SAXENA and NIGAM (1975) evolved a transformation which provides designs for restricted exploration using Symmetric Simplex designs. In this paper a procedure has been given which provides alternative designs with uniform exploration in constrained mixture experiments. The procedure is illustrated by an example.
Simple, sensitive and on‐line fluorescence monitoring of photodegradation of phenol and 2‐naphthol
Authors: He Yihua , Lv Yi , Hu Jing , Qi Linlin , Hou Xiandeng
Published: April 2007

A simple molecular fluorescence spectrometer based on a hand‐held CCD spectrometer was constructed for on‐line monitoring of the photodegradation of pollutants. A high‐pressure Hg vapour lamp was used for the UV photodegradation and simultaneously for the fluorescence excitation. Phenol and 2‐naphthol were selected as the targets for this preliminary study. Using peak fluorescence, figures of merit for monitoring these two hydroxybenzene were obtained. Degradation efficiencies with different homogeneous photocatalyst systems were investigated, including UV only, UV/H2O2 and UV/Fe3+ degradation systems. The kinetics modelling showed that their photodegradation fitted the Langmuir–Hinshelwood model. Results showed that the proposed method is potentially applicable to both on‐line real‐time monitoring and field analysis. Copyright © 2007 John Wiley & Sons, Ltd.
Simultaneous determination of glucose, fructose and lactose in food samples using a continuous‐flow chemiluminescence method with the aid of artificial neural networks
Authors: Li Baoxin , He Yuezhen
Published: April 2007

In this study, a simple continuous‐flow chemiluminescence (CL) system was developed for simultaneous determination of glucose, fructose and lactose in ternary mixtures of reducing sugars without previous separation. This method was based on the different kinetics of the individual sugars in the oxidation reaction with potassium ferricyanide. The known luminol–K3Fe(CN)6 CL system was used to measure the kinetic data of the system. The CL intensity was measured and recorded every second from 1 to 300 s. The data obtained were processed chemometrically using an artificial neural network. The relative standard errors of prediction for three analytes were <5%. The proposed method was successfully applied to the simultaneous determination of the three sugars in some food samples. Copyright © 2007 John Wiley & Sons, Ltd.
A new sensitive flow‐injection chemiluminescence method for the determination of H2‐receptor antagonists
Authors: Tang Yu‐Hai , Wang Nan‐Nan , Xiong Xun‐Yu , Xiong Feng‐Mei , Sun Si‐Juan
Published: April 2007

Based on the chemiluminescence (CL) intensity generated from the potassium ferricyanide [K3Fe(CN)6]–rhodamine 6G system in sodium hydroxide (NaOH) medium, a new sensitive flow‐injection chemiluminescence (FI–CL) method has been developed, validated and applied for the determination of three kinds of H2‐receptor antagonists: cimetidine (CIMT), ranitidine (RANT) hydrochloride and famotidine (FAMT). Under the optimum conditions, the linear range for the determination was 1.0 × 10−9–7.0 × 10−5 g/ml for CIMT, 1.0 × 10−9–5.0 × 10−5 g/mL for RANT hydrochloride and 5.0 × 10−9–7.0 × 10−5 g/mL for FAMT. During 11 repeated measurements of 1.0 × 10−6 g/mL sample solutions, the relative standard deviations (RSDs) were all <5%. The detection limit was 8.56 × 10−10 g/mL for CIMT, 8.69 × 10−10 g/mL for RANT hydrochloride and 2.35 × 10−9 g/mL for FAMT (S:N = 3). This method has been successfully implemented for the analysis of H2‐receptor antagonists in pharmaceuticals. Copyright © 2007 John Wiley & Sons, Ltd.
H4 histone tail mediated DNA–DNA interaction and effects on DNA structure, flexibility, and counterion binding. A molecular dynamics study
Authors: Korolev Nikolay , Nordenskiöld Lars
Published: April 2007

All‐atom molecular dynamics (MD) simulations were performed during 30–45 ns for a system of three identical DNA 22‐mers, 14 short fragments of the charged H4 histone tail peptide fragment (amino acids 5–12, KGGKGLGK) with K+ counterions, and explicit water. The simulation setup mimics the crowded conditions of DNA in eukaryotic chromatin. To assess the influence of tail fragments on DNA structure and dynamics, a “control” 20 ns MD simulation was carried for a system with the same DNA and water content but in the absence of oligopeptides. Results of DNA interaction with the histone tail fragments, K+, and water is presented. DNA structure and dynamics and its interplay with the histone tail fragments binding are described. The charged side chains of the lysines play a major role in mediating DNA–DNA attraction by forming bridges and coordinating to phosphate groups and electronegative sites in the minor groove. Binding of all species to DNA is dynamic. Some of the tail fragments while being flexible and mobile in each of its functional groups remain associated near certain locations of the DNA oligomer. The present work allows capturing typical features of the histone tail‐counterion‐DNA structure, interaction, and dynamics. © 2007 Wiley Periodicals, Inc. Biopolymers 86: 409–423, 2007.

This article was originally published online as an accepted preprint. The “Published Online” date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com
Functional Characterization of the Recombinant N‐Methyltransferase Domain from the Multienzyme Enniatin Synthetase
Authors: Hornbogen Till , Riechers Sean‐Patrick , Prinz Bianka , Schultchen Jeffrey , Lang Christine , Schmidt Sebastian , Mügge Clemens , Turkanovic Suada , Süssmuth Roderich D. , Tauberger Eva , Zocher Rainer
Published: April 2007

A 51 kDa fusion protein incorporating the N‐methyltransferase domain of the multienzyme enniatin synthetase from Fusarium scirpi was expressed in Saccharomyces cerevisiae. The protein was purified and found to bind S‐adenosyl methionine (AdoMet) as demonstrated by cross‐linking experiments with 14C‐methyl‐AdoMet under UV irradiation. Cofactor binding at equilibrium conditions was followed by saturation transfer difference (STD) NMR spectroscopy, and the native conformation of the methyltransferase was assigned. STD NMR spectroscopy yielded significant signals for H2 and H8 of the adenine moiety, H1’ of D‐ribose, and SCH3 group of AdoMet. Methyl group transfer catalyzed by the enzyme was demonstrated by using aminoacyl‐N‐acetylcysteamine thioesters (aminoacyl‐SNACs) of L‐Val, L‐Ile, and L‐Leu, which mimic the natural substrate amino acids of enniatin synthetase presented by the enzyme bound 4′‐phosphopantetheine arm. In these experiments the enzyme was incubated in the presence of the corresponding aminoacyl‐SNAC and 14C‐methyl‐AdoMet for various lengths of time, for up to 30 min. N‐[14C‐Methyl]‐aminoacyl‐SNAC products were extracted with EtOAc and separated by TLC. Acid hydrolysis of the isolated labeled compounds yielded the corresponding N‐[14C‐methyl] amino acids. Further proof for the formation of N‐14C‐methyl‐aminoacyl‐SNACs came from MALDI‐TOF mass spectrometry which yielded 23 212 Da for N‐methyl‐valyl‐SNAC, accompanied by the expected postsource decay (PSD) pattern. Interestingly, L‐Phe, which is not a substrate amino acid of enniatin synthetase, also proved to be a methyl group acceptor. D‐Val was not accepted as a substrate; this indicates selectivity for the L isomer.
Effect of mammographic service screening on stage at presentation of breast cancers in Sweden
Authors:   Swedish Organised Service Screening Evaluation Group
Published: April 2007

BACKGROUND

Previous results have shown a reduction in mortality with service screening in Sweden on the order of 40%. If the rate of tumors at a later stage were similarly reduced, this would give further support to the mortality findings.

METHODS

The rates of lymph node‐positive cancers, of tumors >2 cm in pathological size, and of tumors of TNM stage II or worse before and after the introduction of screening were compared in 13 areas in Sweden, adjusted for changes in overall incidence during the period of study and stratified by age (40–49 and 50–69 years).

RESULTS

Data were obtained on a total of 23,092 cancers and 10,177,113 person‐years of observation. In women exposed to screening in the screening epoch, there was a significant 45% reduction in tumors of size >2 cm compared with the prescreening (relative risk [RR] = 0.55, 95% confidence interval [CI]: 0.46–0.66) in the 40–49 age group, and a 33% reduction in the 50–69 group (RR = 0.67, 95% CI: 0.62–0.72). For lymph node‐positive and stage II+ disease, there were smaller but still significant reductions. No reduction in incidence in later‐stage disease was observed in the unexposed women in the screening epoch.

CONCLUSIONS

Screening has significantly and substantially reduced the rates of larger tumors and lymph node‐positive breast cancer in Sweden, and the magnitude of the reduction is consistent with the reduction in breast cancer mortality. Cancer 2007. © 2007 American Cancer Society.
Almost global existence for Hamiltonian semilinear Klein‐Gordon equations with small Cauchy data on Zoll manifolds
Authors: Bambusi D. , Delort J.‐M. , Grébert B. , Szeftel J.
Published: April 2007

This paper is devoted to the proof of almost global existence results for Klein‐Gordon equations on Zoll manifolds (e.g., spheres of arbitrary dimension) with Hamiltonian nonlinearities, when the Cauchy data are smooth and small. The proof relies on Birkhoff normal form methods and on the specific distribution of eigenvalues of the Laplacian perturbed by a potential on Zoll manifolds. © 2007 Wiley Periodicals, Inc.
Wave Propagation through sparse potential barriers
Authors: Denisov Sergey A.
Published: April 2007

We prove that the three‐dimensional Schrödinger operator with slowly decaying sparse potential has an a.c. spectrum that fills ℝ+. A new kind of WKB asymptotics for Green's function is obtained. The absence of positive eigenvalues is established as well. © 2007 Wiley Periodicals, Inc.
Fine structure of the zeros of orthogonal polynomials IV: A priori bounds and clock behavior
Authors: Last Yoram , Simon Barry
Published: April 2007

We prove locally uniform spacing for the zeros of orthogonal polynomials on the real line under weak conditions (Jacobi parameters approach the free ones and are of bounded variation). We prove that for ergodic discrete Schrödinger operators, Poisson behavior implies a positive Lyapunov exponent. Both results depend on a priori bounds on eigenvalue spacings for which we provide several proofs. © 2007 Wiley Periodicals, Inc.
Compactness along the branch of semistable and unstable solutions for an elliptic problem with a singular nonlinearity
Authors: Esposito Pierpaolo , Ghoussoub Nassif , Guo Yujin
Published: April 2007

We study the branch of semistable and unstable solutions (i.e., those whose Morse index is at most 1) of the Dirichlet boundary value problem − Δu = λf(x)/(1 − u)2 on a bounded domain Ω ⊂ ℝN, which models—among other things—a simple electrostatic microelectromechanical system (MEMS) device. We extend the results of 11 relating to the minimal branch, by obtaining compactness along unstable branches for 1 ≤ N ≤ 7 on any domain Ω and for a large class of “permittivity profiles” f. We also show the remarkable fact that powerlike profiles f(x) ≅ |x|α can push back the critical dimension N = 7 of this problem by establishing compactness for the semistable branch on the unit ball, also for N ≥ 8 and as long as

As a byproduct, we are able to follow the second branch of the bifurcation diagram and prove the existence of a second solution for λ in a natural range. In all these results, the conditions on the space dimension and on the power of the profile are essentially sharp. © 2007 Wiley Periodicals, Inc.
Initial stage of genetic mapping in Ciona intestinalis
Authors: Kano Shungo
Published: April 2007

The use of classic genetics is emerging in the ascidian Ciona intestinalis; recent advances in genomics and high‐quality developmental and evolutionary studies have made this animal an attractive model for research purposes. Genetic mapping in Ciona will likely make a major contribution to ascidian genomics and developmental biology by providing support for genome assembly and annotation and for the isolation of genes with particular mutations, while construction of genetic maps advances classic genetics in this species. Two major issues must be overcome before fine genetic maps can be constructed: the choice of proper genetic backgrounds and the establishment of laboratory strains. A high degree of polymorphism is useful for genetic mapping if we consider particular combinations of genetic backgrounds and techniques, although it is necessary to pay attention to the confused classification of C. intestinalis. Thus, it is preferred to establish laboratory strains instead of using samples with various genetic backgrounds. As these issues are unresolved, only amplified fragment length polymorphism–based maps have been created, while bulk segregant analysis is expected to isolate markers flanking mutant loci. However, rich genomic resources should facilitate the next stage of genetic map construction based on type I markers using coding sequences. The meiotic events that occur in crossing experiments for mapping purposes should shed light on population genetics and speciation issues. The results of such investigations may provide feedback for comparative genomics and developmental genetics in the near future. Developmental Dynamics 236:1768–1781, 2007. © 2007 Wiley‐Liss, Inc.
The DVE changes distal epiblast fate from definitive endoderm to neurectoderm by antagonizing nodal signaling
Authors: Miura Shigeto , Mishina Yuji
Published: April 2007

To assess the function of the distal visceral endoderm (DVE) of embryonic day 5.5 (E5.5) embryos, we established a system to directly ablate the DVE and observe the consequences after culture. When the DVE was successfully ablated, such embryos (DVE‐ablated embryos) showed deregulated expression of Nodal and Wnt3 and ectopically formed the primitive streak at the proximal portion of the embryo. The DVE and anterior visceral endoderm (AVE) are implicated in the development of neurectoderm. We found that the distal epiblast of E5.5 embryo rotates anteriorly by the beginning of gastrulation. These cells remained to be anteriorly located during gastrulation and contributed to the ectoderm in the anterior side of the embryo. This indicates that the distal epiblast of E5.5 embryo becomes neurectoderm in normal development. In DVE‐ablated embryos, the distal epiblast did not show any movement during culture and was abnormally fated to early definitive endoderm lineage. The data suggest that down‐regulation of Nodal signaling in the distal epiblast of E5.5 embryo may be an initial step of neural development. Developmental Dynamics 236:1602–1610, 2007. Published 2007 Wiley‐Liss, Inc.
Development of a new method for analysis of Sudan dyes by pressurized CEC with amperometric detection
Authors: Liu Shaofeng , Zhang Xue , Lin Xucong , Wu Xiaoping , Fu Fengfu , Xie Zenghong
Published: April 2007

A new analytical method, pressurized CEC (pCEC) with amperometric detection (AD) using 1.5 μm RP nonporous silica packed columns has been developed for the rapid separation and determination of four Sudan dyes in hot chilli. The influence of several experimental parameters on the retention behavior has been investigated. The electrochemical oxidation of Sudans I–IV separated by pCEC can be reliably monitored with a carbon electrode at +0.95 V (vs. Ag/AgCl). Fast and efficient separation of the analytes was achieved within 7 min by pCEC under the optimum conditions with an ACN/water (95:5%) mobile phase containing formic acid (pH 4.3), 5% acetone and 0.002% triethylamine using a separation voltage of 12 kV. The detection limits for four Sudan dyes ranged from 8.0 × 10−7 to 1.2 × 10−6 mol/L. To evaluate the feasibility and reliability of this method, the proposed pCEC‐AD method was further demonstrated with hot chilli samples spiked with Sudan dyes.
Simultaneous determination of cefepime and vancomycin in plasma and cerebrospinal fluid by MEKC with direct sample injection and application for bacterial meningitis
Authors: Yang Yuan‐Han , Wu Wen‐Yi , Yeh Hsin‐Hua , Chen Su‐Hwei
Published: April 2007

A simple MEKC with UV detection at 214 nm for simultaneous analysis of cefepime and vancomycin in plasma and in cerebrospinal fluid (CSF) by direct injection without any sample pretreatment is described. The separation of cefepime and vancomycin from biological matrices was performed at 25°C using a BGE consisting of a Tris buffer with SDS and methanol as the electrolyte solution. Under optimal MEKC conditions for biological samples, good separations with high efficiency and short analysis time are achieved. Several parameters affecting the separation of the drugs from biological matrices were studied, including methanol, pH, and concentrations of the Tris buffer and SDS. The linear ranges of the method for the determination of cefepime and vancomycin in plasma and in CSF using imidazole or cefazolin as an internal standard, respectively, were all over the range of 1–30 μg/mL; the detection limits of cefepime and vancomycin in biological matrices (injection 10 kV, 15 s) were 0.3 and 0.5 μg/mL, respectively. The applicability of the proposed method for the determination of cefepime and vancomycin in plasma and CSF collected after intravenous administration of the drugs in patients with meningitis was demonstrated.
Impact of phase and timing jitter on IFDMA systems
Authors: Simon E. , Legouable R. , Hélard M. , Liénard M.
Published: April 2007

In this paper, we investigate the sensitivity of Interleaved Frequency Division Multiple Access (IFDMA) systems to phase and timing jitter. With this aim, the theoretical expressions of the Signal to Interference plus Noise Ratio (SINR) degradation are derived at the decision device input in the presence of phase and timing jitter. The obtained degradation expressions can be evaluated by means of numerical integration. They are shown as a function of the load for various parameters of jitter model. Moreover, it is demonstrated that when assuming a full load, performance degradations do not depend on data block length, compression factor and jitter spectral content as long as the transmitted data block length is large enough. Furthermore, we investigate how the Nyquist filter rolloff impacts the performance degradation. Copyright © 2007 John Wiley & Sons, Ltd.
Constellation inference for polar LEO satellite networks by delay probing
Authors: Wang Junfeng , She Chundong , Liu Jin
Published: April 2007

As a key part of Next Generation Network (NGN) infrastructure, next generation satellite networks are expected to support a variety of applications with diverse performance requirements. This paper argues the necessities of developingbuilt‐inLow Earth Orbit (LEO) satellite constellation inference algorithms. Combined with thorough understanding of the characteristics of underlying satellite network and traffic dynamics, constellation inference is the preliminary step to provide Internet Service Providers (ISPs) an efficient way for network monitoring, system design, traffic engineering and performance promotion.

To infer the constellation, adivide‐and‐conquermechanism is developed for each parameter estimation by delay probing carried out between two terminals located at the same geographic positions. Performance evaluation on several popular polar LEO constellations proves the accuracy and efficiency of the developed constellation measurement algorithms. The geographic position limitation of the delay probing terminals for a valid constellation inference is also analysed in the paper. Copyright © 2007 John Wiley & Sons, Ltd.