bluuebunny/crossref_metadata_2025 huggingface dataset:
Bemerkungen zur Aufstellungsbestimmung zweilagiger Instrumente und die Auswahl günstiger Sterne
Authors: Pauscher H.
Published: June 2010

Es wird gezeigt, daß es nicht gleichgültig ist, welche Deklination und Zenitdistanz die für eine Aufstellungsbestimmung zweilagiger Instrumente benutzten Sterne haben. Wenn Instrumental‐ und Aufstellungsfehler durch Einstellen von Sternen im Meridian in beiden Fernrohrlagen bestimmt werden sollen, ist es günstig, Polsterne, Zenitsterne, Äquatorsterne und Horizontsterne in geeigneter Weise zu kombinieren. Zwar tragen Sterne, die eine dazwischenliegende Deklination haben, zur Fehlerbestimmung ebenfalls bei, jedoch gehen sie nur mit geringem Gewicht in die Ausgleichung ein.
Katalogkorrektionen der Form Δαα aus Zeitbestimmungen mit Durchgangs‐Instrumenten
Authors: Uhink W.
Published: June 2010

Zur Ermittlung von Korrektionen der Form Δαα werden die Differenzen von zwei Zeitbestimmungen derselben Nacht benutzt, wobei für den Verlauf der Korrektionen von vornherein ein periodischer Ansatz verwandt wird.–Vergleich mit Ergebnissen, die auf andere Weise erhalten worden sind.
Intergalaktische Absorption und scheinbare Verteilung der Galaxien
Authors: Hoffmeister C.
Published: June 2010

Es wird die Frage geprüft, ob die Existenz einer interstellaren oder intergalaktischen Absorptionswolke dadurch vorgetäuscht werden kann, daß eine reale Leere besteht und daß, anstelle der wahren Leuchtkraftfunktion, die Annahme gleicher Leuchtkraft für alle Galaxien benutzt wird. Es wird gezeigt, daß auch bei Einführung von Leuchtkraftfunktionen mit stetigem Anstieg bis zu den schwächsten Leuchtkräften Leerstellen immer daran erkannt werden können, daß die Statistik bei Ausdehnung auf noch schwächere Objekte, als sie der Leerstelle entsprechen, bald wieder fast normale Werte ergeben muß, weil der von der Leerstelle verursachte Ausfall absolut schwacher Objekte durch die mit der Entfernung zunehmende Anzahl statistisch unwirksam gemacht wird.
Bahnbestimmung von 4 Meteoren des Perseidenstroms 1961
Authors: Marx S.
Published: June 2010

Die Bahnelemente von vier Meteoren, die im August 1961 photographisch beobachtet wurden, sind wiedergegeben. Außerdem werden von den vier Meteorspuren die Daten in der Erdatmosphäre mitgeteilt.
Beobachtungsergebnisse an Veränderlichen Sternen
Authors: Pohl E. , Kizilirmak A.
Published: June 2010

Als Ergebnis von lichtelektrischen und visuellen Beobachtungen werden 177 Minima von 54 Bedeckungsveränderlichen, 26 Maxima von 5 RR Lyrae‐Sternen, 11 Maxima von 11 δ Cephei‐Sternen, 22 Maxima und 1 Minimum von 6 Mira‐Sternen und Halbregelmäßigen mitgeteilt.
Der Lichtwechsel der Bedeckungsveränderlichen CT Tauri, UU Cancri, EK und BM Cassiopeiae
Authors: Beyer M.
Published: June 2010

Während der W UMa‐Charakter des bislang als RW Aur‐Stern klassifizierten Veränderlichen CT Tau wegen der Kommensurabilität seiner Periode mit dem mittleren Sonnentag bis vor kurzem verborgen blieb, ließen die Beobachtungen von EK Cas jahrelang Zweifel bestehen, ob ein Algol‐ oder β Lyrae‐Lichtwechsel mit doppelter Periode vorhanden ist. Die beiden Veränderlichen UU Cnc und BM Cas sind β Lyrae‐Sterne mit relativ langen Perioden, deren Bedeckungslichtwechsel durch die physische Veränderlichkeit einer Komponente ihrer Systeme gestört wird.
The Analysis of Life Table and Follow‐up Data with Covariates Using Poisson Regression Model
Authors: Chen Qi‐Guang
Published: June 2010

The Poisson regression model for the analysis of life table and follow‐up data with covariates is presented. An example is presented to show how this technique can be used to construct a parsimonious model which describes a set of survival data. All parameters in the model, the hazard and survival functions are estimated by maximum likelihood.
A Study of Second Order Approximation of Some Ratio Type Strategies
Authors: Kothwala N. H. , Gupta P. C.
Published: June 2010

For estimating the mean of a finite population using information on an auxiliary variable, the conventional ratio strategies and strategies due to Srivastava (1967), Reddy (1973), Gupta (1978), Sahai (1979) and Adhvaryu‐Gupta (1983) have been studied. Asymptotic expressions for the second order approximations of biases and mean square errors of these strategies have been obtained. The suitability of these strategies have been discussed with the help of live data.
Bayesian Insight Into a Robust Two‐sample t‐Test Based on Asymmetric Censored Samples
Authors: Balakrishnan N.
Published: June 2010

A robust two‐sample Student t‐type procedure based on symmetrically censored samples proposed by Tiku (1980, 1982a, b) is studied from the Bayesian point of view. The effect of asymmetric censoring on this procedure is investigated and a good approximation to its posterior distribution in this case is worked out. An illustrative example is also presented.
On Confidence Regions in Multiple Assays
Authors: Bennett B. M.
Published: June 2010

In multiple assays a ‘Standard’ preparation is compared in a single assay with two or more ‘Test’ preparations (Finney, 1978, ch. 11). In addition to the estimation of the relative potency of the ‘Test’ preparations the question arises as to simultaneous confidence limits, or else a joint confidence region for these relative potencies. This paper compares a joint confidence region using a LR statistic with separate limits based on Fieller's theorem.

These results are presented in an Example on a multiple assay of two tuberculin preparations A, B compared with a Standard one (data of Wadley, Finney, 1978, Table 11.1).
Precision of Estimation of the Treatment Contrasts and the Intra‐block Matrix of Block Designs
Authors: Gupta S. C.
Published: June 2010

In many practical situations the experiment is conducted using a block design, and it is desired to estimate a given set of contrasts with variances none of which is greater than a corresponding set of specified variances: In the present paper the form of the intra‐block matrix of a design is, therefore, derived for such situations. Usefulness of the results given is illustrated with the help of examples. The construction of two‐plot block designs is shown to be particularly straightforward.
Simultaneous Analysis of Variance Tests Using Friedman's χ Statistics
Authors: Jensen D. R.
Published: June 2010

This study develops simultaneous tests for shifts in marginal distributions pertaining to complete two‐way multivariate data not having Gaussian errors. Gerig's (1969) statistics based on ranks are used, a special case yielding Friedman's (1937) χ Statistics statistics for the one‐dimensional marginal distributions. Exact α‐level procedures are not now available. Instead, approximate but conservative tests are constructed using available tables together with suitable probability inequalities. A variational result permits unlimited tests even when these are suggested by the data. The procedures are illustrated using data from field studies with peanuts; some extensions are noted; and selected percentage points are provided to support some of the tests.
Methods for Fitting the Right‐Truncated Weibull Distribution to Life‐Test and Survival Data
Authors: Wingo Dallas R.
Published: June 2010

This paper develops mathematical and computational methods for fitting, by the method of maximum likelihood (ML), the two‐parameter, right‐truncated Weibull distribution (RTWD) to life‐test or survival data. Some important statistical properties of the RTWD are derived and ML estimating equations for the scale and shape parameters of the RTWD are developed. The ML equations are used to express the scale parameter as an analytic function of the shape parameter and to establish a computationally useful lower bound on the ML estimate of the shape parameter. This bound is a function only of the sample observations and the (known) truncation point T. The ML equations are reducible to a single nonlinear, transcendental equation in the shape parameter, and a computationally efficient algorithm is described for solving this equation. The practical use of the methods is illustrated in two numerical examples.
A Comparison Between a Parametric and a Non‐Parametric Method of Estimating the Percentiles of a Difference
Authors: Taylor Jeremy M. G.
Published: June 2010

A parametric and a nonparametric method of estimating the percentiles of a difference are compared. The parametric method assumes an underlying normal distribution and the nonparametric method estimates the distribution from the residuals. Applications to immunology are discussed.
A Comparative Statistical Analysis of Genetic Distances. I ‐ Estimation of Distances and of their Variances: Distribution of the Estimators
Authors: Katz M.
Published: June 2010

We present a Monte‐Carlo simulation analysis of the statistical properties of absolute genetic distance and of Nei's minimum and standard genetic distances. The estimation of distances (bias) and of their variances is analysed as well as the distributions of distance and variance estimators, taking into account both gamete and locus samplings. Both of Nei's statistics are non‐linear when distances are small and consequently the distributions of their estimators are extremely asymmetrical. It is difficult to find theoretical laws that fit such asymmetrical distributions. Absolute genetic distance is linear and its distributions are better fit by a normal distribution. When distances are medium or large, minimum distance and absolute distance distributions are close to a normal distribution, but those of the standard distance can never be considered as normal. For large distances the jack‐knife estimator of the standard distance variance is bad; another standard distance estimator is suggested. Absolute distance, which has the best mathematical properties, is particularly interesting for small distances if the gamete sample size is large, even when the number of loci is small. When both distance and gamete sample size are small, this statistic is biased.
Log‐Linear Models for Linked Loci: Variances of Estimated Parameters
Authors: Haber Michael
Published: June 2010

In a recent work (Haber, 1984) the author described a system of two genetic loci in terms of loglinear models. The present note provides a method for estimating the variances of the estimated parameters in these models.
General Analysis of Covariance Models for the Split Block and Related Block Designs
Authors: Monlezun C. J. , Blouin D. C.
Published: June 2010

Exact test statistics and confidence intervals for a general split block ANOCOVA model are derived. With a single covariate, each statistic for testing main effect A, main effect B, and the AxB interaction has one less numerator degree of freedom than its counterpart in the ordinary ANOVA without a covariate. Sufficient conditions on the model parameters which allow these lost numerator degrees of freedom to be regained are given, as are exact statistics and confidence intervals for the corresponding reduced models. A note of caution is offered when constructing test statistics for reduced versions of the general model using the method of generalized least squares. General analysis of covariance models for two other block designs are presented.
Estimation and Tests of Mendelian Inheritance in Small Samples of Human Families
Authors: Bchini M. , Goux J. M.
Published: June 2010

Estimation of parameters in human genetics is usually performed by Maximum Likelihood methods for large samples relying on asymptotic results. With the aim of evaluating the importance of the bias resulting from sample size, two sets of human family data have been analysed. The bias is not very important, but programs have been elaborated, giving better estimations. The tests of hypotheses from these estimations have also been considered.
Small Sample Bias and Variance of Lincoln‐Petersen and Bailey Estimators
Authors: Bonett D. G.
Published: June 2010

The Lincoln‐Petersen and Bailey estimators of an unknown population size were compared in a computer simulation of capture‐recapture sampling with replacement from small populations. The Bailey estimator was negatively biased and had smaller variance than the Petersen estimator. The Petersen estimator tended to be positively biased. The Lincoln‐Petersen variance estimator tended to be positively biased while the Bailey variance estimator was negatively biased.
On the Estimation of the Mean with Random Number Of Observations. (Comments on a Paper by M. Singh and V. K. Gupta)
Authors: Lindqvist B. G.
Published: June 2010

In this paper we study the problem of estimating the mean when the number of observations taken on each unit is a random variable. The estimator proposed by M. Singh and V. K. Gupta (1980) is discussed and modified. It is argued, however, that the arithmetic mean is a more appropriate choice of estimator.
Shannon's Measure and its Use in the Analysis of Cancer Data
Authors: Jain R. K.
Published: June 2010

In this paper, Shannon's measure of uncertainty is explored in the analysis of cancer data. The term ‘cancer diversity’ is defined and its potential application is illustrated.
Orthogonal Components in MANOVA with Application to an Anesthesiology Experiment
Authors: Koziol J. A.
Published: June 2010

We describe orthogonal components in multivariate analysis of variance, and illustrate their value when assessing restricted alternatives.
A Procedure for Clustering Means of Unequal‐Sized Samples in ANOVA
Authors: Neumann H.
Published: June 2010

The proposed procedure “SECOLICO” is based on the sequential construction of linear contrasts. After an analysis of variance the procedure is able to classify the treatments represented by mean values of unequal‐sized samples made at random into distinguishable groups. For the purpose of illustrating the procedure “SECOLICO” a simplified example is given.
Age Preference in Sexual Choice and the Basic Reproduction Number of HIV/AIDS
Authors: Knolle Helmut
Published: June 2010

It is shown that the concept of the basic reproduction number R, which has arisen in the theory of acute air‐borne infections, needs essential modifications when it is applied to chronic, sexually transmitted infections. A new definition of R is given, which takes into account the aging of the infected person and its partners during the course of the infection. Thereby the impact of age preference in sexual choice on the spread of HIV/AIDS can be quantified with little computational effort. It turns out that for low‐risk groups, R is by far smaller than conventional calculation would suggest, and that the frequency of partnerships between people with distant ages exerts greater influence on R than the infection probability per contact and the number of successive partnerships within the infectious period. It is suggested that a high incidence of partnerships between older men and very young women is a major reason for the AIDS epidemic in Africa.
Comparison of Two Exponential Distributions
Authors: Bristol David R. , Desu M. M.
Published: June 2010

The problem of comparing two treatments with respect to a continuous response variable, following an exponential distribution, is considered. It is assumed that a relevant comparative clinical trial is planned to either (i) test that the effect of one treatment is larger or not much smaller than that of the other, (ii) test whether the treatments are equivalent, or (iii) select the better treatment when they may not be equivalent and otherwise assert equivalence. Statistical procedures for achieving these goals are proposed and description of the required sample sizes is given with the necessary tables.
Small Sample Exact Power of the Range from a Symmetric Multinomial Distribution
Authors: Bennett B. M. , Holmes E. N.
Published: June 2010

The authors (1968) have previously given tables of the percentage points of the range (= w) of r samples from a multinomial distribution of r cells each with probability r−1, r = 2(1)10. This paper presents the small sample power of w for r = 2(1)6 under alternatives H to the null hypothesis H0 of a symmetric multinomial distribution. The alternatives are of the form H: pi=r−1+c1n1/2 i = 1, …, r, where the c's are such that ∑ci=0, i. e. H consists of a set of multinomial probabilities approaching H0 of 0(n−1/2). Table 1 gives values of the power of the range test, and Table 2 consists of selected comparisons of the power with respect to the X2 index of dispersion.
A Comparative Study on Approximative and Exact Tests in Two‐dimensional Contingency Tables
Authors: Enke H. , Bismarck M.
Published: June 2010

Often the statistician is faced with the necessity of analysing a × b‐contingency tables which are partially very sparsely occupied beyond a very‐well occupied “kernel”. The weak part shall not be due to misclassification or miscalculation. By the aid of a fictive example an analysing strategy is discussed combining exploratory and confirmatory elements and comparing the use of Exact Fisher Test and Freeman‐Halton Test with Pearson's X2 and Fisher's Maximum Likelihood Quotient Statistics Y2.
Time‐variant Spectral Analysis of Electroencephalograms
Authors: Volke H.‐J. , Dettmar P.
Published: June 2010

Methods usually applied for analysis of biological signals, as a rule, presuppose stationarity of the time series under investigation. Such kind of approach, however, will certainly be connected with an essential loss of information as dynamic properties of the system are excluded from consideration a priori. The method of time‐variant spectral analysis of the EEG suggested in this paper, on the contrary, provides time‐relatedchanges of the spectral coefficients. Additinonally, a decomposition of the EEG into its natural componentsas well as a combined EEG‐/EP‐analysis is enabled.
Logistic Transformation Regression Estimators of Heritability
Authors: Prabhakaran V. T. , Jain J. P.
Published: June 2010

Three logistic transformation estimators are proposed to deal with the problem of inadmissible estimates of intra‐sire regression heritability (h2). These are compared with the estimators of earlier workers. The logistic transformation estimator with exponential correction is shown empirically to give more consistent estimates.
Prediction in Random Coefficient Regression Models
Authors: Bondeson Jan
Published: June 2010

Much attention has been given to the problem of predicting future observations for some individual within a random coefficient regression (RCR) model, using the previous observations on that individual as well as the information from the rest of the data material. In this paper, the literature on this subject is critically reviewed and new methods of linear prediction are proposed for the general RCR model. Exact results are derived for the mean squared errors of some predictors in a special case, but this is not possible in the general RCR model when its parameters are not known. In this model, the old and new predictors are compared in a simulation study, and further illustrated by prediction in a medical data material.
A Medical Application of the General Random Coefficient Regression Model
Authors: Bondeson J. , Lanke Jan
Published: June 2010

RCR models are reviewed. Various variance estimators are described, among them a new one. These variance estimators are compared in a simulation study. An obstetric data set is subjected to a detailed analysis by means of RCR techniques. In particular, interval estimation is considered.
Null Distribution of the Small Sample Mean Correlation Coefficient: An Application to Medical Research
Authors: Bhatti Muhammad I.
Published: June 2010

In this note we outlined the procedure to obtain upper tail percentage points of the distribution of the average of k independent sample correlation coefficient (r) each of which is based on n pairs of observations. Null distribution of r demonstrates its application to medical research.
Comparison of Decontaminants Over Arbitrary Dose Ranges Using Dose‐Response Survival and Contamination Experiment Data
Authors: Trajstman A. C.
Published: June 2010

TRAJSTMAN (1989) defined indices for assessing the performance of decontaminants used in the culturing of a micro‐organism. One index used was the probability that the micro‐organism of interest survives without being contaminated by foreign micro‐organisms. In TRAJSTMAN (1989) attention was given to the maximum of this probability. In the present paper the performance of the decontaminant is assessed by considering, over dose ranges of interest, the mean probability that the organism survives without contamination.
Estimation of Degree of Dominance and Gene Frequency in Random Mating Populations
Authors: Dhillon B. S.
Published: June 2010

An estimate of mean degree of dominance of genes affecting a quantitative trait in random mating populations cannot, in general, be obtained with the available methodology. Three mating designs have been proposed for the estimation of mean degree of dominance and mean gene frequency over loci. These designs are based on related S1, full‐sib and half‐sib families and on the families developed by simultaneous selfing and crossing the parents in either nested or factorial manner.
An Almost Unbiased Correlation Estimator of Heritability
Authors: Verma D. , Jain J. P.
Published: June 2010

Assuming normality of observations an almost unbiased estimator of heritability (h2) for half‐sib data design has been obtained. Results of bias in the conventional estimator for several combinations of sire/dam number and h2 are discussed for the balanced situation.
Monte Carlo Confidence Bounds for Inter‐Event and Nearest Neighbour Distribution Functions of Random Points in a Square
Authors: Koen Chris
Published: June 2010

Random distributions of N points in a square were simulated by computer, interpoint and nearest neighbour distances were calculated and corresponding distribution functions found. The results of 1000 repetitions of this process were used to find approximate 90, 95 and 99 % confidence bounds for the distribution functions. Calculations were performed in the range N = 10 to N = 350. Results are given in tabular form.
A Related Problem in Bioavailability/Bioequivalence Studies — Estimation of the Intrasubject Variability With a Common CV
Authors: Chow Shein‐Chung , Tse Siu‐Keung
Published: June 2010

The problem of characterizing the intrasubject variability in bioavailability/bioequivalence studies when the intrasubject variability differs from subject to subject is considered. To account for the heterogeneity of the intrasubject variability, a conditional random effects model that assumes a common coefficient of variation (CV) for each subject is proposed. This common CV is used to assess the intrasubject variability. Several procedures are developed for estimating the common CV. The proposed estimators are compared asymptotically. An extensive simulation study is conducted to study their finite sample performances.
A Different Approach to the Analysis of Person‐Years Data
Authors: Le Chap T.
Published: June 2010

The observed mortality of a group of individuals often needs to be compared with that expected from the death rates of the national population, with allowance made for period, age, sex and race. This is achieved by the person‐years or subject‐years method. A different approach is proposed which leads to new test statistics and confidence intervals which may be used with small samples.
A New Approach to Estimation of Relative Risks Due to Two or More Risk Factors Under Multiple Matching in Case‐Control Studies
Authors: Ejigou Ayenew
Published: June 2010

The analysis of case‐control data using logistic regression involves making some critical model assumptions. In the analysis of matched data for which the values of the matching variable(s) are unavailable, use of logistic regression presupposes that odds ratios are homogeneous over the levels of the matching variable (s); this is done since logistic regression cannot, at present, provide a way of testing for the homogeneity of odds ratios.

In our model, it is possible, as in logistic regression, to estimate odds ratios, check the multiplicativity of effects, or test for the significance of association. In addition, and unlike logistic regression, our model enables one to test for the homogeneity of the odds ratios over the levels of the matching variable(s) even when explicit information is not available on the matching variable(s).
Tests of Hypotheses in Density Follow‐Up Studies
Authors: Bennett B. M.
Published: June 2010

This paper discusses statistical methods for situations in which two or more (k + 1) exposure groups, including a reference one, are compared with respect to rate ratios, or incidence density ratios (IDR) (e.g. MIETTINEN, 1976). Data are assumed available on population times (PT) experienced in the exposure groups.

The logit transformation or its generalizations (e.g. Cox, 1970 are utilized in order to obtain suitable tests for the hypotheses involved. Three examples illustrate these methods, including approximate and exact confidence limits for the IDR's (k = 1). For the case of (k + 1) groups a linear contrast for the hypothesis of a trend is derived as well as its standard error.
Tables for Studentized Multivariate Maximum Ranges and their Application by Maximum Range Tests
Authors: Royen Th.
Published: June 2010

The maximum range test as a closed multiple test procedure for all pairwise comparisons of several independent samples was described by ROYEN (1988) and (1989). For the number k of samples, the dimension d and some suitable degrees of freedom v between 10 and ∞ the following tables are contained in this paper:

bounds for the studentized multivariate maximum range for 2≦k≦12, 2≦d≦6 and the familywise type I error rates α = 0.01 (table 1.1) and α = 0.01 (table 1.2), furthermore bounds for the studentized univariate maximum range for 2≦k≦15 and α = 0.01 (table 2). The corresponding bounds with α = 0.05 for univariate maximum ranges have been tabulated in ROYEN (1989).

Some examples for the application of these bounds by maximum range tests are included.
Relative Frequency Estimation in Multiple Outcome Measurement with Misclassifications
Authors: Jolayemi E. T.
Published: June 2010

Fallible classification scheme is known to produce inconsistent relative frequency estimates from a polychotomous variable. These estimates however can be improved upon by the use of a sub‐sample that results in a square table. In this research we highlight the method of improvement.
Two Remarks on the Comparison of Simultaneous Confidence Intervals
Authors: Ński W. Zieli
Published: June 2010

One way of comparing simultaneous confidence intervals is to compare the length of individual confidence intervals. Simultaneous confidence intervals are the better the shorter individual confidence intervals are. It is shown that such comparison has no sense.
A Decomposition of Linear Diagonals‐Parameter Symmetry Model for Square Contingency Tables with Ordered Categories
Authors: Tomizawa Sadao
Published: June 2010

For square contingency tables with ordered categories, this paper gives a decomposition for AGRESTI'S (1983) linear diagonals‐parameter symmetry (LDPS) model into GOODMAN'S (1979) diagonals‐parameter symmetry model and the linear diagonals‐parameter marginal symmetry model introduced in this paper. It is also pointed out that the likelihood ratio statistic for the LDPS model is equal to the sum of those for the decomposed two models.
URegression and Survival Analysis
Authors: Nagelkerke N. J. D. , Plummer F. A.
Published: June 2010

The problem of survival analysis with covariates when observations are subject to irregular interval censoring is considered. A proportional hazards model is assumed. A pseudo likelihood based on the comparison of all pairs of individuals whose survival times can be ordered, is proposed. Statistical properties of the maximum pseudo likelihood estimator and its score test are explored. Several examples are presented, one of which is an examination of the effect of covariates on HIV seroconversion.
The Model Selection for One‐Dimensional Multinomials
Authors: Jolayemi E. Tejumola
Published: June 2010

The use of the common test statistics in obtaining appropriate null hypothesis or model for one‐dimensional qualitative data is re‐examined. We propose alternatives which do not depend on the distributional approximation of the test statistics. We examine these alternatives using data from a medical set‐up and conclude that these alternatives are adequate for descriptive purposes which is what is usually desirable for such data. An extra caution is required however, if estimates are of importance especially for such data which depends on a predictor variable.
Models Having Structure of Various Symmetry Plus Diagonal Exponential Frequencies Applied to Data from Endometrial Cancer Study
Authors: Tomizawa Sadao
Published: June 2010

For the analysis of square contingency tables with ordered categories, this note proposes some models having the structure of symmetry or asymmetry plus the main‐diagonal exponential frequencies. These models are applied to the data from the Los Angeles endometrial cancer study in BRESLOW and DAY (1980, p. 185).
A Method for the Estimation of Crop Varieties Stability
Authors: Martynov S. P.
Published: June 2010

A method for point and interval stability estimation of crop varieties or hybrids is suggested. The method makes it possible to estimate the ability of a genotype to combine high potential yield with minimal yield reduction under unfavourable conditions. The stability measure is a weighted sum of standardized deviations of a trait value from the mean in each trial (location or year) of an ecological experiment. The application of the method is illustrated by a numerical example.
Optimum Biased Spring Balance Weighing Designs Under Equal Correlations of Errors
Authors: Ceranka B. , Katulska K.
Published: June 2010

The paper deals with the problem of estimating the individual weights of objects under a biased spring balance weighing design with equal correlations of errors in the model. A lower bound for the variance of each of the estimated weights resulting from this biased spring balance weighing design is obtained and a necessary and sufficient condition for this lower bound to be attained is given. The incidence matrix of a BIB design has been used to construct optimum biased spring balance weighing designs.
An Alternative Approach for the Assessment of Bioequivalence Between Two Formulations of a Drug
Authors: Chow Shein‐Chung , Shao Jun
Published: June 2010

The problem of the assessment of bioequivalence between a test formulation (T) and a reference formulation (R) of a drug using a two‐way crossover experiment is considered. To claim bioequivalence between two formulations, it is required by the United States Food and Drug Administration (FDA) to demonstrate that the true ratio of means μT/μR of pharmacokinetic parameters of concern falls within some reasonable limits (e.g., (80%, 120%)) with certain assurance. A commonly used approach is to construct an approximate 90% confidence interval for μT/μR and compare it with (80%, 120%). In this paper, an exact approach according to the FDA's criteria is proposed. The proposed procedure is derived by constructing an exact confidence region (an ellipse) for (μR, μT) and comparing it with the region bounded by μT = 0.8 μR and μT = 1.2 μR. Bioequivalence is concluded if the ellipse is within the critical region.
9.3 KDa components of the injected venom of Conus purpurascens define a new five‐disulfide conotoxin framework
Authors: Möller Carolina , Marí Frank
Published: June 2010

The 83‐residue conopeptide (p21a) and its corresponding nonhydroxylated analog were isolated from the injected venom ofConus purpurascens. The complete conopeptide sequences were derived from Edman degradation sequencing of fragments from tryptic, chymotryptic and cyanogen bromide digestions. p21a has a unique, 10‐cystine/5‐disulfide 7‐loop framework with extended 10‐residue N‐terminus and a 5‐residue C‐terminus tails, respectively. p21a has a 48% sequence homology with a recently described 13‐cystine conopeptide, con‐ikot‐ikot, isolated from the dissected venom of the fish‐hunting snailConus striatus. However, unlike con‐ikot‐ikot, p21a does not form a dimer of dimers. MALDI‐TOF mass spectrometry suggests that p21a may form a noncovalent dimer. p21a is an unusually large conotoxin and in so far is the largest isolated from injected venom. p21a provides evidence that theConusvenom arsenal includes larger molecules that are directly injected into the prey. Therefore, cone snails can utilize toxins that are comparable in size to the ones commonly found in other venomous animals. © 2010 Wiley Periodicals, Inc. Biopolymers (Pept Sci) 96: 158–165, 2011.
Guidance on Safety/Health for Process Intensification Including MS Design. Part IV: Case Studies
Authors: Klais O. , Albrecht J. , Carson D. , Kraut M. , Lö P. , Minnich C. , Olschewski F. , Reimers C. , Simoncelli A. , Uerdingen M.
Published: June 2010

The new technology of process intensification by multiscale equipment can significantly contribute to the achievement of a safer design by switching from batch/semi‐batch to continuous operation combined with a reduction of the inventory of hazardous substances in critical stages. On the other hand, the shift to higher space‐time‐yields and temperatures comprises new risks (see Parts I and II). A tool was developed for preliminary risk assessment to cover characteristic features of micro‐designed equipment, called HAZOP‐LIKE study (see Part III). The generic case studies were applied to two demonstration projects within the IMPULSE project: sulfur dioxide oxidation and the alkylation reaction for the production of ionic liquids. The generic templates proved to be applicable and support comprehensive risk analysis studies on processes with hidden deviations not obviously following traditional HAZOP studies.
Effects of Soft Particle Deformability and Particle/Pore Size Ratio on the Blocking Mechanism in Dead‐End Microfiltration
Authors: Tung K. L. , Hu C. C. , Chuang C. J. , Hwang K. J. , Wu T. Y.
Published: June 2010

Microfiltrations of Saccharomyces cerevisiae yeast particles of various deformabilities were conducted to examine the blocking mechanism due to particle deposition during the initial stage of the microfiltration process. The S. cerevisiae particles were treated with glutaraldehyde to form particles of various deformabilities. To compare differences in the blocking mechanisms among the different particles during microfiltration, a blocking model was adopted to estimate the filtrate flux, which accounts for initial blocking due to pore obstruction and subsequent blocking due to the growth of a cake over these initially blocked regions. The surface morphology of the cake layer on the membrane surface and the blockage by particles in membrane pores was examined by scanning electron microscopy (SEM). Analysis of the blocking mechanism of particles of varying deformability during microfiltration based on the blocking model indicated that softer particles resulted in more severe pore blocking problems and greater flux decline. A comparison of the theoretical results with experimental observations by SEM showed good qualitative agreement.
Two‐Step Thermal Spin Transition and LIESST Relaxation of the Polymeric Spin‐Crossover Compounds Fe(X‐py)2[Ag(CN)2]2 (X=H, 3‐methyl, 4‐methyl, 3,4‐dimethyl, 3‐Cl)
Authors: Rodríguez‐Velamazán J. Alberto , Carbonera Chiara , Castro Miguel , Palacios Elías , Kitazawa Takafumi , Létard Jean‐François , Burriel Ramón
Published: June 2010

In the series of polymeric spin‐crossover compounds Fe(X‐py)2[Ag(CN)2)]2 (py=pyridine, X=H, 3‐Cl, 3‐methyl, 4‐methyl, 3,4‐dimethyl), magnetic and calorimetric measurements have revealed that the conversion from the high‐spin (HS) to the low‐spin (LS) state occurs by two‐step transitions for three out of five members of the family (X=H, 4‐methyl, and X=3,4‐dimethyl). The two other compounds (X=3‐Cl and 3‐methyl) show respectively an incomplete spin transition and no transition at all, the latter remaining in the HS state in the whole temperature range. The spin‐crossover behaviour of the compound undergoing two‐step transitions is well described by a thermodynamic model that considers both steps. Calculations with this model show low cooperativity in this type of systems. Reflectivity and photomagnetic experiments reveal that all of the compounds except that with X=3‐methyl undergo light‐induced excited spin state trapping (LIESST) at low temperatures. Isothermal HS‐to‐LS relaxation curves at different temperatures support the low‐cooperativity character by following an exponential decay law, although in the thermally activated regime and for aX=H and X=3,4‐dimethyl the behaviour is well described by a double exponential function in accordance with the two‐step thermal spin transition. The thermodynamic parameters determined from this isothermal analysis were used for simulation of thermal relaxation curves, which nicely reproduce the experimental data.
Triptycene‐Derived Calix[6]arenes: Synthesis, Structures, and Their Complexation with Fullerenes C60 and C70
Authors: Tian Xiao‐Hong , Chen Chuan‐Feng
Published: June 2010

Two pairs of novel triptycene‐derived calix[6]arenes 4 a,b and 5 a,b have been efficiently synthesized through both one‐pot and two‐step fragment‐coupling strategies starting from 2,7‐bis(hydroxymethyl)‐1,8‐dimethoxytriptycene 1. Subsequent demethylation of 4 a,b and 5 a,b with BBr3 in dry dichloromethane gave the macrocyclic compounds 6 a,b and 7 a,b. Treatment of either 4 a or 6 a with AlCl3 resulted in the same debutylated product 8, while 9 was similarly obtained from either 5 a or 7 a. Structural studies revealed that all of the macrocycles have well‐defined structures with fixed conformations both in solution and in the solid state owing to the introduction of the triptycene moiety with a rigid three‐dimensional (3D) structure, making them very different from their classical calix[6]arene counterparts. As a consequence, it was found that all of these the triptycene‐derived calix[6]arenes could encapsulate small neutral molecules in their cavities in the solid state. Moreover, it was also found that the macrocycles 4 b and 5 b showed highly efficient complexation abilities toward fullerenes C60 and C70, forming 1:1 complexes with association constants ranging from (5.22±0.20)×104 to (8.68±0.30)×104 M−1.
2‐Hydroxyazobenzenes to Tailor pH Pulses and Oscillations with Light
Authors: Emond Matthieu , Le Saux Thomas , Maurin Sylvie , Baudin Jean‐Bernard , Plasson Raphael , Jullien Ludovic
Published: June 2010

This paper evaluates the 2‐hydroxyazobenzene platform for tailoring proton concentration pulses and oscillations with monochromatic light. The easily prepared 2‐hydroxyazobenzenes exhibit large absorptions in the near‐UV range. Photoisomerization was investigated by UV/Vis absorption, 1H NMR spectroscopy, and steady‐state fluorescence emission. In the whole investigated series, the trans stereoisomer of the 2‐hydroxyazobenzene motif provides the corresponding cis derivative with an action cross section in the 103 M−1 cm−1 range. At the same time, photoisomerization is accompanied by a significant pK drop of the phenol group. According to the phenyl‐substituent pattern, cis‐to‐trans thermal back‐isomerization can be tuned in the 10 ms–100 s range. Up to 2 units of reversible pH drops or pH oscillations on the 10 s timescale have been obtained by appropriately tailoring single‐wavelength illumination of 2‐hydroxyazobenzene solutions.
Synthesis of Functionalized Indoles with a Trifluoromethyl‐Substituted Stereogenic Tertiary Carbon Atom Through an Enantioselective Friedel–Crafts Alkylation with β‐Trifluoromethyl‐α,β‐enones
Authors: Blay Gonzalo , Fernández Isabel , Muñoz M. Carmen , Pedro José R. , Vila Carlos
Published: June 2010

Chiral complexes of BINOL‐based ligands with zirconium tert‐butoxide catalyze the Friedel–Crafts alkylation reaction of indoles with β‐trifluoromethyl‐α,β‐unsaturated ketones to give functionalized indoles with an asymmetric tertiary carbon center attached to a trifluoromethyl group. The reaction can be applied to a large number of substituted α‐trifluoromethyl enones and substituted indoles. The expected products were obtained with good yields and ees of up to 99 %.
Self‐Sorted Assembly in a Mixture of Donor and Acceptor Chromophores
Authors: Molla Mijanur Rahaman , Das Anindita , Ghosh Suhrit
Published: June 2010

A simple and novel supramolecular approach for orthogonal self‐assembly of donor and acceptor chromophores has been demonstrated. Suitably designed 1,5‐dialkoxynaphthalene (DAN) and naphthalene tetracarboxylic acid diimide (NDI) derivatives were used as the donor and acceptor systems, respectively. The molecular design for self‐sorting relies upon the precise control over the placement of the self‐complementary hydrogen‐bonding units (amide functionality) with respect to the individual chromophore. By design, the distances between the two amide groups in the donor and acceptor chromophores are not identical, and consequently the effect of the hydrogen‐bonding interaction cannot be maximised in the case of alternate donor–acceptor‐type π‐stacking. Thus a relatively weak charge‐transfer interaction is expected to be sacrificed, and segregated assembly among the individual chromophores should be enforced by virtue of the much stronger effects of hydrogen bonding and π–π stacking. Detailed spectroscopic studies were carried out to probe the mode of self‐assembly in various derivatives of the DAN–NDI donor–acceptor pairs to establish the utility of the molecular design as a generalised one for orthogonal self‐assembly.
A Computational Study of Rhodium Pincer Complexes with Classical and Nonclassical Hydride Centres as Catalysts for the Hydroamination of Ethylene with Ammonia
Authors: Uhe Andreas , Hölscher Markus , Leitner Walter
Published: June 2010

The catalytic hydroamination of ethylene with ammonia was investigated by means of density functional theory (DFT) calculations. An initial computational screening of key reaction steps (CN bond formation, NH bond cleavage), which are assumed to be part of a catalytic cycle, was carried out for complexes with the [M(L)]‐complex fragment (M=Rh, Ir; L=NCN, PCP; NCN=2,5‐bis(dimethylaminomethyl)benzene, PCP=2,5‐bis‐ (dimethylphosphanylmethyl)benzene). Based on the evaluation of activation barriers, this screening showed the rhodium compound with the NCN ligand to be the most promising catalyst system. A detailed investigation was carried out starting with the hypothetical catalyst precursor [Rh(NCN)(H)2(H2)] (1). A variety of activation pathways to yield the catalytically active species [Rh(NCN)(H)(NH2)] (5), as well as [Rh(NCN)(C2H5)(NH2)] (17), were identified. With 5 and 17 several closed catalytic cycles could be calculated. One of the calculated cycles is favoured kinetically and bond‐forming events have activation barriers low enough to be put into practice. The calculations also show that for experimental realisation the synthesis of 1 is not necessary, as the synthesis of 17 would establish an active catalyst directly without the need for activation. Oligomerisation of ethylene would be possible in principle and would be expected as a competitive side reaction. Accordingly not only ethylamine would be observed in an experimental system, as amines with longer carbon chains also can be formed.
Fabrication of a Biocompatible and Conductive Platform Based on a Single‐Stranded DNA/Graphene Nanocomposite for Direct Electrochemistry and Electrocatalysis
Authors: Zhang Qian , Qiao Yun , Hao Fei , Zhang Ling , Wu Shuyao , Li Ying , Li Jinghong , Song Xi‐Ming
Published: June 2010

A novel electrochemical platform was designed by combining the biocompatibility of single‐stranded DNA (ss‐DNA) and the excellent conductivity of graphene (GP). This nanocomposite (denoted as ss‐DNA/GP) was first used as an electrode material for the immobilization and biosensing of redox enzymes. On the basis of electrostatic interactions, horseradish peroxidase (HRP) self‐assembled with ss‐DNA/GP on the surface of a glassy carbon (GC) electrode to form an HRP/ss‐DNA/GP/GC electrode. UV/Vis and FTIR spectra were used to monitor the assembly process and indicated that the immobilized HRP on the ss‐DNA/GP matrix retained its native structure well. A pair of stable and well‐defined redox peaks of HRP with a formal potential of about −0.26 V (vs. Ag/AgCl) in a pH 7.0 phosphate buffer solution were obtained at the HRP/ss‐DNA/GP/GC electrode; this demonstrates direct electron transfer between the immobilized HRP and the electrode. In addition, the modified electrode showed good electrocatalytic performance towards H2O2 with high sensitivity, wide linear range, and good stability. Accordingly, the ss‐DNA/GP nanocomposite provides a novel and efficient platform for the immobilized redox enzyme to realize direct electrochemistry and has a promising application in the fabrication of third‐generation electrochemical biosensors.
Reactions of Alkynes with [RuCl(cyclopentadienyl)] Complexes: The Important First Steps
Authors: Dutta Barnali , F. E. Curchod Basile , Campomanes Pablo , Solari Euro , Scopelliti Rosario , Rothlisberger Ursula , Severin Kay
Published: June 2010

Cyclopentadienyl–ruthenium half‐sandwich complexes with η2‐bound alkyne ligands have been suggested as catalytic intermediates in the early stages of Ru‐catalyzed reactions with alkynes. We show that electronically unsaturated complexes of the formula [RuCl(Cp^)(η2‐RC≡CR′)] can be stabilized and crystallized by using the sterically demanding cyclopentadienyl ligand Cp^ (Cp^=η5‐1‐methoxy‐2,4‐tert‐butyl‐3‐neopentyl‐cyclopentadienyl). Furthermore we demonstrate that [RuCl2(Cp^)]2 is an active and regioselective catalyst for the [2+2+2] cyclotrimerization of alkynes. The first elementary steps of the reaction of mono(η2‐alkyne) complexes containing {RuCl(Cp*)} (Cp*=η5‐C5Me5) and {RuCl(Cp^)} fragments with alkynes were investigated by DFT calculations at the M06/6‐31G* level in combination with a continuum solvent model. Theoretical results are able to rationalize and complement the experimental findings. The presence of the sterically demanding Cp^ ligand increases the activation energy required for the formation of the corresponding di(η2‐alkyne) complexes, enhancing the initial regioselectivity, but avoiding the evolution of the system towards the expected cyclotrimerization product when bulky substituents are present. Theoretical results also show that the electronic structure and stability of a metallacyclic intermediate is strongly dependent on the nature of the substituents present in the alkyne.
ChemInform Abstract: Electrical Resistivity, Oxidation Resistivity and Hardness of Single Crystal Compounds in the Er—Rh—B System.
Authors: SHISHIDO T. , KUDOU K. , OKADA S. , YE J. , OKU M. , HORIUCHI H. , FUKUDA T.
Published: June 2010

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform Abstract: Structure and Characterization of a Mixed Crystal Rb2SO4×Te(OH)6.
Authors: DAMMAK M. , KHEMAKHEM H. , MHIRI T. , KOLSI A. W. , DAOUD A.
Published: June 2010

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform Abstract: Structural Chemistry, Magnetism and Thermodynamic Properties of Ln2Pd2In.
Authors: GIOVANNINI M. , MICHOR H. , BAUER E. , HILSCHER G. , ROGL P. , FERRO R.
Published: June 2010

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.