bluuebunny/crossref_metadata_2025 huggingface dataset:
Response Curve Comparison by Pseudo‐Multivariate Two‐Sample Configural Frequency Analysis
Authors: Krebs Harald , Ising Marcus , Janke Wilhelm , Macht Michael , von Eye Alexander , Weijers Heinz‐Gerd , Weyers Peter
Published: May 2007

This paper introduces pseudo‐multivariate Configural Frequency Analysis (CFA) for comparison of time series from two independent samples. The method extends application of standard two‐sample CFA, bi‐prediction CFA, and longitudinal CFA. Methods for identification of uni‐discrimination types and bi‐discrimination types are proposed. The pseudo‐multivariate CFA is applied to sets of response curves from two independent samples of rats. The experimental group of rats was exposed to a stressful noise condition. The control group was not exposed to stress. Amount of food intake was measured over five days. Longitudinal discrimination types suggest that, under stress, rats reduce food intake at first, increase intake as habituation to stress increases, and show greater day‐to‐day variability of intake.
Prediction of Response to Selection and Inbreeding Coefficient under Assortative Mating
Authors: Nomura T.
Published: May 2007

A method for predicting response to selection and inbreeding coefficient under the continuous use of assortative mating was derived. Using the method, numerical computation was carried out, and the utility of assortative mating in the selection programmes was evaluated. It was shown that the continuous use of assortative mating could not produce an appreciable additional increase in intermediate‐ or long‐term selection response.
Estimation of Differences and Ratios of Average Age at First Occurrence
Authors: Boshuizen Hendriek C. , Greenland Sander
Published: May 2007

Average age at first occurrence of a disease is easier to interpret than the incidence rate, which can be difficult to interpret for a common disease. Basic methods for estimating univariate differences and ratios for average age at first occurrence are outlined and illustrated with a real‐life example.
An Application of Renewal Theory to Contraceptive Follow‐up Studies, Exemplified by an Intrauterine Device Study
Authors: Liu Peng T. , Chow Lien P.
Published: May 2007

Contraceptive practice consists of a series of recurrent events of use and nonuse. Application of the life table technique for analysis of multiple‐segment contraceptive usage is not entirely satisfactory. In this paper the renewal process approach is applied to the results of contraceptive follow‐up studies involving all segments of use. By means of this model, it is possible to estimate the proportion of current users, the average duration of actual use, and the average number of segments used by the acceptors. The practical importance of these parameters for the evaluation of family planning programs is considered.
A Monte Carlo Test for Variance Homogeneity in Linear Models
Authors: Piepho Hans‐Peter
Published: May 2007

A Monte Carlo procedure is proposed for testing homogeneity of variances in linear models. The method is applicable to a variety of common experimental designs. It is valid when errors are independently normally distributed. Under nonnormality the test is expected to behave robust in a similar fashion as Levene's test. Three examples are given to demonstrate the method.
A Confidence Region Approach for Assessing Equivalence in Variability of Bioavailability
Authors: Chen Keh‐Wei , Li Gang , Sun Yanging , Chow Shein‐Chung
Published: May 2007

The problem for assessment of equivalence in variability of bioavailability between two drug products is considered. Similar to the method for assessing bioequivalence in average bioavailability proposed by Chow and Shao (1990), an exact confidence region approach is derived when the intersubject variance is known. When the intersubject variance is unknown, a large sample approximation is considered. The proposed method for assessing equivalence of variability of bioavailability appears to be asymptotically uncorrelated with that of Chow and Shao (1990) for average bioavailability. As a result, the proposed method in conjunction with the method proposed by Chow and Shao (1990) constitutes a confidence region approach for assessing population bioequivalence. An example concerning a bioequivalence trial with 24 healthy volunteers is provided to illustrate the proposed method.
Confidence Intervals for Microbial Density Using Serial Dilutions with MPN Estimates
Authors: Garthright Wallace E. , Blodgett Robert J.
Published: May 2007

An alteration to Woodward's methods is recommended for deriving a 1 — α confidence interval for microbial density using serial dilutions with most‐probable‐number (MPN) estimates. Outcomes of the serial dilution test are ordered by their MPNs. A lower limit for the confidence interval corresponding to an outcome y is the density for which y and all higher ordered outcomes have total probability α/2. An upper limit is derived in the analogous way. An alteration increases the lowest lower limits and decreases the highest upper limits. For comparison, a method that is optimal in the sense of null hypothesis rejection is described. This method ranks outcomes dependent upon the microbial density in question, using proportional first derivatives of the probabilities. These and currently used methods are compared. The recommended method is shown to be more desirable in certain respects, although resulting in slightly wider confidence intervals than De Man's (1983) method.
Dependence Functions and Frailties
Authors: Oluyede Broderick O.
Published: May 2007

This note considers association between nonnegative random variables in which the two observed survival times depend on an unobservable random variable via the proportional hazard model. When the random variables are subject to censoring, the conditional hazard functions provides a reasonable means of describing the association between the two variables. A numerical example demonstrating association in disease incidence in ordered pairs of individuals is analysed. Also, examples of distributions satisfying the notions of dependence considered are provided.
On Indifference Zone Selection with a Preference Threshold
Authors: Coolen F. P. A. , van der Laan P.
Published: May 2007

This paper discusses a selection criterion that generalizes the well‐known concept of indifference zone selection through a preference threshold. A population is preferred to another population if the difference in the sums of observed values exceeds a given nonnegative threshold value. We present an argument for this selection rule by modelling preference by imprecise previsions. We aim at guidelines to design a selection experiment, which is characterized by two numbers: the number of necessary observations per population, and the preference threshold. Next to the probability of correct selection we also need a second specification. In this paper we consider a probability of false selection that is strongly related to the minimum probability of correct selection. Based on this model the outcome of an experiment may be ‘no selection’, at least not based on strong preference of a single population. The ideas are presented through a simple selection problem for normal populations with common known variance. Although the theory has a frequentist nature, the derivation and justification of the selection rule through imprecise previsions relies on Bayesian foundations, and via this route we gain more insight into the selection criterion.
Initial Value Dependence: A Comparison of Two Methods For Its Study
Authors: Raykov Tenko , Penev Spiridon
Published: May 2007

This article is concerned with the comparison of slope estimator precision in regression analysis and the structural relationships approach (e.g., Humak, 1983, ch. 3; Kendall and Stuart, 1977), as it is relevant for their applications when testing for initial value dependence in biomedical and behavioral contexts of repeated assessments (e.g., Blomqvist, 1977; Wall, 1977). As a basis for the comparison of the two methods, the mean square error is adopted. In the general case, it is argued for an informed (data‐dependent) choice between regression analysis and the structural relationships approach. For the apparent majority of biomedical and behavioral studies of the phenomenon of initial value depenence, this comparison suggests that structural relationships is the preferable approach leading to more trustworthy substantive conclusions.
A Note on Lancaster's Procedure for the Combination of Independent Events
Authors: Koziol James A.
Published: May 2007

Lancaster (1961) generalized Fisher's (1932) nonparametric procedure for combining independent p‐values by transforming Pi from the i‐th experiment to a chi‐squared random variable with di degrees of freedom, with di not necessarily equal to 2. We explore the relationship between Lancaster's procedure and a weighted Lipták procedure (Koziol and Tuckwell, 1994) under which Pi is transformed to the standard normal scale. We investigate approximations to the null distribution of Lancaster's test procedure, chi‐squared with d degrees of freedom. We find that the Cornish‐Fisher (1960) expansions and the Lugannani‐Rice (1980) saddlepoint approximations are quite accurate, for non‐integral values of d, and for values of d as low as 20.
Forecast of Sugarcane Yield Using Eye Estimate Alongwith Plant Characters
Authors: Agrawal Ranjana , Jain R. C.
Published: May 2007

The present study proposes to include farmers' appraisal (eye estimate) as one of the variables in the models alongwith plant characters. This will reduce the number of plant character in the model, thus reducing the cost on data collection. This has been demonstrated through regression and probability models.
On Choice of Subjects and Replicates in Estimating Among and Within Subject Variation
Authors: Wong Weng Kee , Lachenbruch Peter A. , Clements Philip J.
Published: May 2007

We consider the problem of choosing the number of replicates and number of subjects in a components of variance problem which optimizes various criteria. The case study here involves patients suffering from systemic sclerosis (Scleroderma), a form of rheumatic disease that is potentially disabling. Under the physical constraints imposed on the study, we find that using 2 or 3 replicates with as many patients as possible is the optimal strategy for several criteria.
Tests of Bivariate Symmetry with a One‐sided Alternative in the Analysis of Variance
Authors: Bhattacharya Bhaskar
Published: May 2007

We consider a two‐factor experiment in which the factors have the same number of levels with a natural ordering among levels. We test the hypothesis that the effects of the two treatments are symmetric against a one‐sided alternative using the likelihood ratio criteria. Test of the one‐sided alternative as a null hypothesis against no restriction has also been studied. Exact distribution theory under the null hypothesis is derived and is shown to be a weighted mixture of chi‐square distributions. An example is used to illustrate the procedure.
Pair Rank Set Sampling
Authors: Muttlak Hassen A.
Published: May 2007

Ranked set sampling (RSS) as suggested by McIntyre (1952) may be modified to introduced a new sampling method called pair rank set sampling (PRSS), which might be used in some area of application instead of the RSS to increase the efficiency of the estimators relative to the simple random sampling (SRS) method. Estimators of the population mean are considered. An example using real data is presented to illustrate computations.
A Matrix Formulation for Nonparametric Permutation Tests
Authors: Marcuson Richard
Published: May 2007

Many of the common permutation tests, particularly those from survival analysis, are special cases of a more general methodology. They are based on a single covariance matrix which is simple and can be derived by elementary means. It is, however, surprisingly hard to find a complete treatment of this covariance matrix in the literature. Such a treatment is given here together with a discussion of the permutation tests' uses in data analysis.
Precision Intervals for Estimates of the Difference in Success Rates for Binary Random Variables Based on the Permutation Principle
Authors: Röhmel Joachim
Published: May 2007

Fisher's exact test is a very commonly applied test in clinical trials with a binary outcome variable (e.g. success/failure). However confidence statements about the difference of success rates are usually based on the normal approximation. This may sometimes lead to the confusing statement that the test is statistically significant at a prespecified level while the corresponding confidence interval includes the zero difference and vice versa. Here, we construct precision intervals for the difference of success rates from two independent samples based on the permutation principle which are in perfect agreement with the discrete (permutation) test and compare it to examples from the literature. APL programs are provided.
Catecholamine Response Curves of Male Hypertensives Identified by Lehmacher's Two Sample Configural Frequency Analysis
Authors: Müller Matthias J. , Netter Petra , Von Eye Alexander
Published: May 2007

A new application of LEHMACHER'S (1980) marginal homogeneity sign tests is given by analysis of bivariate response curves (or response surfaces) in two unpaired samples of hypertensive versus normotensive patients. Rationale and computations are illustrated by empirical data from sympathomedullary stress research.
An Overview of Precedence‐Type Tests for Censored Data
Authors: Chakraborti S. , Van Der Laan P.
Published: May 2007

Precedence tests are simple yet robust nonparametric procedures useful for comparing two or more distributions. In this paper precedence‐type tests are considered when the data contain some censored observations. Generalizing the precedence statistic for uncensored data, the precedence tests for censored data are based on the Kaplan‐Meier estimators of the respective distribution functions and the corresponding quantile functions. The literature is reviewed for some two‐sample as well as some multi‐sample problems.
The Prior Distribution of the Minimum and Maximum Distance between Several Marker Loci and Quantitative Trait Loci
Authors: Teuscher F. , Tuchscherer A.
Published: May 2007

In order to control linkage experiments, exact formulas and approximations are derived for the minimum distance between quantitative trait loci and the nearest marker locus. The locations of the loci are assumed to be uniformly distributed over the genome. The locations of the marker loci may be known or unknown. The number and length of the chromosomes are arbitrary and therefore the results are applicable for all kinds of species. Analogous formulas are derived for the maximum distance between the quantitative trait loci and the nearest marker loci. For the probability of linkage more simple expressions are derived. The accuracy of the approximations is checked by a simulation.
Loglinear Symmetry and Quasi‐Symmetry Models for the Analysis of Change
Authors: Meiser Thorsten , Von Eye Alexander , Spiel Christiane
Published: May 2007

Loglinear symmetry and quasi‐symmetry models are proposed as tools for investigating various hypotheses about change. First, a survey of model representations is provided, including model specification in terms of hierarchical loglinear models and in design matrix notation. Secondly, the range of symmetry and quasi‐symmetry models is extended to the joint analysis of several groups. Parameter constraints are discussed which allow one to test specific hypotheses about group differences in symmetric frequency distributions. Finally, symmetry and quasi‐symmetry models are considered for multiway contigency tables. In this context, loglinear total score models are proposed for the analysis of symmetry in several marginal distributions. The proposed models reflect cross‐sectional as well as longitudinal facets of development.
Likelihood‐Weighted Confidence Intervals for the Difference of Two Binomial Proportions
Authors: Lee J. Jack , Serachitopol Dan M. , Brown Barry W.
Published: May 2007

Two new methods for computing confidence intervals for the difference δ = p1 — p2 between two binomial proportions (p1, p2) are proposed. Both the Mid‐P and Max‐P likelihood weighted intervals are constructed by mapping the tail probabilities from the two‐dimensional (p1, p2)‐space into a one‐dimensional function of δ based on the likelihood weights. This procedure may be regarded as a natural extension of the CLOPPER‐PEARSON (1934) interval to the two‐sample case where the weighted tail probability is α/2 at each end on the δ scale. The probability computation is based on the exact distribution rather than a large sample approximation. Extensive computation was carried out to evaluate the coverage probability and expected width of the likelihood‐weighted intervals, and of several other methods. The likelihood‐weighted intervals compare very favorably with the standard asymptotic interval and with intervals proposed by HAUCK and ANDERSON (1986), COX and SNELL (1989), SANTNER and SNELL (1980), SANTNER and YAMAGAMI (1993), and PESKUN (1993). In particular, the Mid‐P likelihood‐weighted interval provides a good balance between accurate coverage probability and short interval width in both small and large samples. The Mid‐P interval is also comparable to COE and TAMHANE'S (1993) interval, which has the best performance in small samples.
Analysis of Randomized Dose‐Finding‐Studies: Closure Test Modifications Based on Multiple Contrast Tests
Authors: Hothorn L. A. , Neuhäuser M. , Koch H.‐F.
Published: May 2007

The power of single contrast tests strongly depends on the a priori unknown shape of the dose response relationship. Two approaches can be used to overcome this major disadvantage: the likelihood ratio test for order restriction or multiple contrast tests. Within the closure principle, the shape for the different hyptheses varies. Therefore multiple contrast tests are used as trend tests. Based on a simulation study the power advantage of this approach in comparison with single contrast tests is demonstrated.
Power of Some Tests for Umbrella Alternatives in the Multi‐Sample Location Problem
Authors: Büning Herbert , Kössler Wolfgang
Published: May 2007

For the c‐sample location problem with umbrella alternatives we present a modification of a test proposed by BARLOW et al. (1972) for trend alternatives. Furthermore, we study a rank version of this modified test following a proposal of CONOVER and IMAN (1981). These tests are compared with the test of MACK and WOLFE (1978) and with some so called Mack‐Wolfe‐type tests in which the Mann‐Whitney statistics are replaced by other two‐sample linear rank statistics. The comparison is referred to the power of the test assuming a broad range of distributions. It will be shown firstly, that for nonnormal data there are tests with higher power than the modification of the test of Barlow et al. and secondly, that for a special distribution there is a Mack‐Wolfe‐type test which is more efficient than is competitors. We also consider the case of unknown peak.
Almost Unbiased Ratio and Product Type Estimators: A New Approach
Authors: Mahajan P. K. , Singh Sarjinder
Published: May 2007

In this paper, we have proposed a new method, consisting of a linear variety of the estimators and a linear constraint to remove the bias appearing in the estimators of the ratio R = Y/X and product P = YX. The percent relative efficiency of proposed estimators has also been demonstrated with numerical illustrations.
A Kinetic Model for Human Platelet Survival with Long‐Lasting Time‐Activity Curves
Authors: Osterode Wolf , Rattay Frank
Published: May 2007

A model is presented that allows for the interpretation of the time course of the level of radiolabeled platelets in terms of platelet survival times, rate constant for removal from circulation, pooling time in an extra pool, the rate at which platelets re‐enter circulation from the extra‐pool, and the size of the plasma pool and extra‐pools. The tenets of the model are that: (1) platelets leave the circulation at a rate proportional to their number per unit volume; (2) of the leaving platelets, a fraction b goes into a pool from which they return into circulation after a pooling time and another fraction (1 ‐ b) is irreversibly destroyed; (3) the platelets in the extra‐pool do not “queue up”, and thus the distribution function describing the probability of return is exponential; and (4) the time activity curve of the radiolabeled platelets can be described by the sum of two exponentials. Under steady state conditions, curve fitting allows determination of the constants determining the time activity curve (the respective amplitudes and rate constants of the two exponentials); mean pooling time; relative pool size; and survival time of platelets. The model is applied to data collected from patients over a period from 10 days following reinjection of autologous radiolabeled platelets.
Estimating the Order of a Sequence of Physiological Changes from Incomplete Data
Authors: Solow Andrew R. , Curran Mary Carla , Bentivegna Flegra
Published: May 2007

The problem considered in this paper is the estimation of the underlying order of m physiological changes from incomplete observations. The observations are incomplete in the sense that, for each individual in the sample, only the identity, but not the order, of the first k < m changes are observed, with k varying between individuals. An application to some data on physiological changes in fish undergoing sex change is presented.
Optimization of Dynamic Plant Nitrogen Uptake, Using Apriori Information of Plant Nitrogen Content
Authors: Vold A. , Sôreng J. S.
Published: May 2007

Emphasizing that model development should be in accordance with the context under consideration, a model for plant nitrogen uptake is developed for use in connection with soil nitrogen models. The aim of the modeling is to improve the accuracy in model simulations of plant nitrogen uptake by application of optimization theory and apriori information of plant nitrogen content. A simple soil nitrogen model is coupled to the plant nitrogen uptake model, and solutions, obtained by two different methods, are presented. Suggestion for how to use the modeling principles in connection with a more complex plant nitrogen uptake model, and apriori information of plant dry weight, is given. It is believed that the modeling principles can also be used on other types of dynamic models with given apriori information.
A Game‐Theoretic Approach to Partitioning Attributable Risks in Epidemiology
Authors: Land Matthias , Gefeller Olaf
Published: May 2007

The concept of attributable risk has been developed to quantify that proportion of disease events in a population that can be ascribed to an exposure factor under study. Typically, several exposures have to be considered simultaneously in observational epidemiological studies when assessing their impact on the disease load. Whenever these exposures are subject of complex interactions the question arises, what contribution should be assigned to each of them. The paper points out that the epidemiological problem of finding “sensible” risk allocation methods can be formalized in a way that is equivalent to the game‐theoretic description of several players that act together in a grand coalition and are faced with the problem of dividing their profit “fairly” among them. The transfer of game‐theoretic results to epidemiology yields a unique method of allocating shares of the joint attributable risk, called partial attributable risks. To each exposure factor. Application and justification of the method are illustrated using data from the G.R.I.P.‐study (Göttinger Risiko‐, Inzidenz‐ und Prävalenzstudie).
An Evaluation of Methods for the Estimation of Sensitivity and Specificity of Site‐Specific Diagnostic Tests
Authors: Ahn Chul
Published: May 2007

The performance of diagnostic tests is often evaluated by estimating their sensitivity and specificity with respect to a traditionally accepted standard test regarded as a “gold standard” in making the diagnosis. Correlated samples of binary data arise in many fields of application. The fundamental unit for analysis is occasionally the site rather than the subject in site‐specific studies. Statistical methods that take into account the within‐subject corelation should be employed to estimate the sensitivity and the specificity of diagnostic tests since site‐specific results within a subject can be highly correlated. I introduce several statistical methods for the estimation of the sensitivity and the specificity of sitespecific diagnostic tests. I apply these techniques to the data from a study involving an enzymatic diagnostic test to motivate and illustrate the estimation of the sensitivity and the specificity of periodontal diagnostic tests. I present results from a simulation study for the estimation of diagnostic sensitivity when the data are correlated within subjects. Through a simulation study, I compare the performance of the binomial estimator pCBE, the ratio estimator pCBE, the weighted estimator pCWE, the intracluster correlation estimator pCIC, and the generalized estimating equation (GEE) estimator PCGEE in terms of biases, observed variances, mean squared errors (MSE), relative efficiencies of their variances and 95 per cent coverage proportions. I recommend using PCBE when σ == 0. I recommend use of the weighted estimator PCWE when σ = 0.6. When σ == 0.2 or σ == 0.4, and the number of subjects is at least 30, PCGEE performs well.
Testing for Absence of Qualitative Interactions Between Risk Factors and Treatment Effects
Authors: Wellek S.
Published: May 2007

The problem of investigating qualitative interactions (QI's) between subsets of patients defined by means of some risk factors, and treatment effects in clinical trials is considered from a viewpoint which leads to interchanging the hypotheses of the testing problem dealed with in the existing literature on QI's. A natural way of approaching this reverse problem is to apply one of the tests available for the original problem of detecting QI's at level 1 — α and to reject the null hypothesis of the new problem if and only if this test accepts. Unfortunately, this would require unbiasedness of the level 1 — α test for existence of QI's to start with, a property which exhibits neither the likelihood ratio procedure derived in the seminal paper of GAIL and SIMON (1985), nor the test based on the extreme order statistics which was introduced by several authors in 1993. Nevertheless we show that there is a valid test for absence of QI's which depends on the extreme values only and coincides with the maximum likelihood ratio procedure for the same problem. Furthermore, the procedure is generalized to the problem of testing for absence of relevant QI's, i.e. of qualitative interactions exceeding some specified tolerance ε > 0.
Confidence Regions for Spectral Peak Frequencies
Authors: Timmer Jens , Lauk M. , Lücking C. H.
Published: May 2007

A procedure is proposed to obtain confidence regions for spectral peak frequencies. The method is based on resampling the periodogram from the estimated spectrum in order to reestimate the spectrum and its peak frequency. We investigate the dependence of the results from the applied spectral estimator in three simulation studies and apply the method to tremor data.
The Bayesian Paradigm and Tree Diagrams with Applications in Genetics
Authors: Wilson S. R.
Published: May 2007

Probability tree diagrams are developed for the calculation and interpretation of conditional probabilities. Their use in Bayesian calculations and, most importantly, for the correct interpretation of results is described. Key practical applications to linkage analysis and evaluation of evidentiary DNA material given.
Parametric Methods for Bivariate Quantile‐Partitioned Tables and the Efficiency of Corresponding Nonparametric Methods
Authors: Borkowf Craig B. , Gail Mitchell H.
Published: May 2007

In order to study the agreement between two continuous measurements on a sample of individuals, epidemiologists sometimes partition the original bivariate data into categories defined by the empirical quantiles of the two marginal distributions. The counts in the resulting two‐way contingency table have the empirical bivariate quantile‐partitioned (EBQP) distribution rather than the conventional multinomial distribution. BORKOWF et al. (1997) developed the asymptotic theory and inferential procedures for estimates of measures of agreement calculated from EBQP tables. In this paper, we develop parametric methods for bivariate quantile‐partitioned (BQP) tables. We use these methods to study the efficiency of nonparametric (EBQP) methods and to improve the precision of estimates of measures of agreement. We present computational methods for estimating certain measures of agreement (kappa, weighted kappa, and row proportions) together with their variances. Numerical studies and an example show that nonparametric (EBQP) estimates of kappa and certain row proportions tend to be quite inefficient compared to parametric estimates, whereas nonparametric estimates of weighted kappa can be relatively more efficient for some underlying distributions. Thus, investigators should weigh the efficiency advantages of parametric estimates against possible biases that can result from choosing an inappropriate parametric model when they employ BQP tables to study agreement.
On Conditions for Validity of the Approximations to Fisher's Exact Test
Authors: Martínandrés A. , Tejedor I. Herranz
Published: May 2007

A 2 × 2 table is analyzed from the conditional viewpoint, using Fisher's exact test, for which there is abundant software nowadays (StatXact, SPSS with the module “Exact Test”, …). Nevertheless, because it is well‐nigh impossible to work the test out “by hand”, it is customary in many books to analyze the table, in an approximate fashion, by using the classic chi‐square test with the appropriate continuity correction, and this is what many researchers do in practice. Unfortunately little research has been carried out on the validity conditions of the test (remember the classic advice that the minimum expected quantity E should be larger than or equal to 5), so that it is applied indiscriminately with the obvious danger of obtaining erroneous results. In this paper the exact validity conditions (which depend not only on E, but also on the real P‐value, on the size of the sample, on the number of tails of the test and on the continuity correction used) are determined, showing that the classic condition E > 5 can be either very strict or quite liberal (depending on the circumstances) and it can even be necessary for the test to have E > 20. A similar study is made of the case of using the binomial approximation, while the Poisson approximation is also discussed.

The article ends with a list of rules and precautions to be borne in mind by researchers using the approximate methods. The strict rules are complex enough to make the researcher want to use the exact test, but simplified (and conservative) rules are also given for those unable to do so.
Bioluminescence imaging for assessment and normalization in transfected cell arrays
Authors: Pannier Angela K. , Ariazi Eric A. , Bellis Abigail D. , Bengali Zain , Jordan V. Craig , Shea Lonnie D.
Published: May 2007

Transfected cell arrays (TCAs) represent a high‐throughput technique to correlate gene expression with functional cell responses. Despite advances in TCAs, improvements are needed for the widespread application of this technology. We have developed a TCA that combines a two‐plasmid system and dual‐bioluminescence imaging to quantitatively normalize for variability in transfection and increase sensitivity. The two‐plasmids consist of: (i) normalization plasmid present within each spot, and (ii) functional plasmid that varies between spots, responsible for the functional endpoint of the array. Bioluminescence imaging of dual‐luciferase reporters (renilla, firefly luciferase) provides sensitive and quantitative detection of cellular response, with minimal post‐transfection processing. The array was applied to quantify estrogen receptor α (ERα) activity in MCF‐7 breast cancer cells. A plasmid containing an ERα‐regulated promoter directing firefly luciferase expression was mixed with a normalization plasmid, complexed with cationic lipids and deposited into an array. ER induction mimicked results obtained through traditional assays methods, with estrogen inducing luciferase expression 10‐fold over the antiestrogen fulvestrant or vehicle. Furthermore, the array captured a dose response to estrogen, demonstrating the sensitivity of bioluminescence quantification. This system provides a tool for basic science research, with potential application for the development of patient specific therapies. Biotechnol. Bioeng. 2007;98; 486–497. © 2007 Wiley Periodicals, Inc.
Separation and determination of isoflavones in red clover by micellar electrokinetic capillary chromatography
Authors: Zhang Yu , Chen Juan , Zhao Liang , Shi Yan‐Ping
Published: May 2007

A micellar electrokinetic capillary chromatography (MECC) method has been developed for the determination of the four isoflavones, i.e. biochanin A, formononetin, genstein and daidzein in red clover (Trifolium Pratense L.). The effect of running buffer pH and concentration were investigated. An electrolyte composed of 30 mm borate, 20 mm sodium dodecyl sulfate (SDS) and 4 mg/mL HP‐β‐CD containing 5% (v/v) ethanol at pH 10.1 provides a satisfactory separation for all the analytes. The applied voltage was 25 kV, and the capillary temperature was kept constant at 25°C with a UV detection at 254 nm. The relative standard deviations (RSD) of the migration time and peak area were less than 1.73 and 3.94% (intra‐day), and 2.29 and 4.38% (inter‐day), respectively, under the optimized separation conditions. Regression equations revealed a good linear relationship between the peak area of each compound and its concentration. The contents of the four compounds in red clover were successfully determined with satisfactory repeatability and recovery. Copyright © 2007 John Wiley & Sons, Ltd.
Can defendants with mental retardation successfully fake their performance on a test of competence to stand trial?
Authors: Everington Caroline , Notario‐Smull Heidi , Horton Mel L.
Published: May 2007

The purpose of this study was to determine whether criminal defendants with mental retardation can feign poor performance on a test of competence to stand trial. Four groups of adjudicated criminal defendants were given a test of competence to stand trial. In the experimental condition, defendants with mental retardation (MR) and mentally typical defendants (non‐MR) were given instructions to fake their performance on the test. In the control, MR defendants and non‐MR defendants took the test under standard conditions. The results indicated that both the MR and non‐MR fakers scored significantly lower than the MR and non‐MR controls. There was no significant difference in the scores of the MR and non‐MR fakers. The results suggest that defendants with mental retardation may be able to successfully fake their performance in certain circumstances. Implications of these findings are discussed. Copyright © 2007 John Wiley & Sons, Ltd.
The function of punishment in the “civil” commitment of sexually violent predators
Authors: Carlsmith Kevin M. , Monahan John , Evans Alison
Published: May 2007

Two experiments find that support for civil commitment procedures for sexually violent predators is based primarily upon the retributive rather than incapacitative goals of respondents. Two discrete samples composed of students (N = 175) and jury‐eligible citizens (N = 200) completed experimental surveys assessing their support or opposition to scenarios in which a sexual predator was to be released after completing his criminal sentence. Respondents were sensitive to likelihood of recidivism only when the initial sentence was sufficiently punitive. When initial sentence was lenient, respondents strongly supported civil commitment without regard to future risk. Results are discussed in light of the U.S. Supreme Court's ruling inKansas v. Hendricks(1997) on the constitutionality of civil commitment laws for sexually violent predators. Copyright © 2007 John Wiley & Sons, Ltd.
Newer concepts for imaging anomalous aortic origin of the coronary arteries in adults
Authors: Angelini Paolo , Flamm Scott D.
Published: May 2007

Of the different kinds of coronary anomalies observed in adults, anomalous origin of a coronary artery from the opposite sinus of Valsalva with an “interarterial” course (ACAOS) entails a high risk of clinical consequences related to the intramural course of the ectopic coronary artery. We review current imaging modalities for differentiating this condition from generally benign coronary anomalies and for quantifying the severity of individual cases. For identifying ACAOS, noninvasive modalities (echocardiography, computed tomographic angiography, and coronary magnetic resonance angiography) are preferred: the favored modalities are transthoracic echocardiography in children and multidetector computed tomography in adults. For evaluating the pathophysiologic mechanisms of ischemia in ACAOS and subclassifying the severity of individual forms, coronary intravascular ultrasonography provides enhanced temporal and spatial resolution. The critical quantifiable features of the coronary anatomy in ACAOS seem to be hypoplasia, lateral compression at the level of the intramural course, and possibly exercise‐related further narrowing of the proximal ectopic segment. Definitive guidelines are being developed for the optimal workup and treatment of ACAOS. © 2007 Wiley‐Liss, Inc.
Highly Stereoselective Peptide Modifications through Pd‐Catalyzed Allylic Alkylations of Chelated Peptide Enolates
Authors: Deska Jan , Kazmaier Uli
Published: May 2007

Deprotonation of peptides in the presence of zinc chloride gives rise to highly reactive nucleophiles that can be subjected to palladium‐catalyzed allylic alkylation reactions. Excellent diastereoselectivities are obtained that are nearly independent of the allylic substrate used. By using this protocol, highly functionalized side chains can also be incorporated in excellent yields and selectivities. The stereochemical outcome of the reaction is exclusively controlled by the peptide chain as long as terminal π‐allyl–palladium complexes are involved. Probably, there is a threefold coordination, at least, of the deprotonated peptide chain to the chelating zinc ion. In such metal peptide complexes, one face of the generated enolate is shielded by the side chain of the adjacent amino acid, thus directing the electrophilic attack onto the opposite face. This behavior explains why an S amino acid always generates an R amino acid (and the other way round).
The genetics and embryology of zebrafish metamerism
Authors: Holley Scott A.
Published: May 2007

Somites are the most obvious metameric structures in the vertebrate embryo. They are mesodermal segments that form in bilateral pairs flanking the notochord and are created sequentially in an anterior to posterior sequence concomitant with the posterior growth of the trunk and tail. Zebrafish somitogenesis is regulated by a clock that causes cells in the presomitic mesoderm (PSM) to undergo cyclical activation and repression of several notch pathway genes. Coordinated oscillation among neighboring cells manifests as stripes of gene expression that pass through the cells of the PSM in a posterior to anterior direction. As axial growth continually adds new cells to the posterior tail bud, cells of the PSM become relatively less posterior. This gradual assumption of a more anterior position occurs over developmental time and constitutes part of a maturation process that governs morphological segmentation in conjunction with the clock. Segment morphogenesis involves a mesenchymal to epithelial transition as prospective border cells at the anterior end of the mesenchymal PSM adopt a polarized, columnar morphology and surround a mesenchymal core of cells. The segmental pattern influences the development of the somite derivatives such as the myotome, and the myotome reciprocates to affect the formation of segment boundaries. While somites appear to be serially homologous, there may be variation in the segmentation mechanism along the body axis. Moreover, whereas the genetic architecture of the zebrafish, mouse, and chick segmentation clocks shares many common elements, there is evidence that the gene networks have undergone independent modification during evolution. Developmental Dynamics 236:1422–1449, 2007. © 2007 Wiley‐Liss, Inc.
Wide‐bore monolithic column for electrochromatography
Authors: Yuan Ruijuan , Ding Guosheng , Guo Yugao , Liu Danning , Bao James J.
Published: May 2007

A new wide‐bore electrophoresis (WE) system adopting an inner cooling device was set up to perform electrochromatography. In this system, a quartz tube of 1.2 mm inner diameter was used as the separation channel. The Joule heat generated during electrophoresis was removed timely through the outer surface of the quartz tube and a cooling capillary inserted into the quartz tube. A proper coolant passed through the cooling capillary to further improve the cooling efficiency. In the primary research, a polyacrylamide monolithic column was successfully prepared in this quartz tube. Then it was evaluated in the electrochromatographic mode. An electric field strength as high as 625 V/cm can be applied to this system without obvious deviation of the current from the linear curve of the Ohm plot. Sample volume as high as 1 μL was injected into the WE system and reasonable efficiency was obtained for separation of the test compounds.
Rapid determination of genomic DNA length for new bacteriophages
Authors: Serwer Philip , Hayes Shirley J. , Thomas Julie A. , Griess Gary A. , Hardies Stephen C.
Published: May 2007

dsDNA viruses with long genomes (>200 kb) are expected to be a major source of novel genes. To rapidly characterize the genomes of newly isolated dsDNA bacteriophages, we develop here a procedure for the PFGE of intact long DNA genomes from bacteriophage particles in unfractionated, infected cell lysates of either liquid or gelled cultures. The DNA used for PFGE is suitable for sequencing after extraction with phenol. The PFGE is tuned to the range of expected DNA lengths. This procedure bypasses the isolation of bacteriophage particles and is useful for PFGE analysis of DNA from dissected zones of bacteriophage plaques.
Determination of catecholamines by CE with direct chemiluminescence detection
Authors: Liu Yan‐Ming , Wang Cheng‐Quan , Mu Hai‐Bei , Cao Jun‐Tao , Zheng Yan‐Li
Published: May 2007

A rapid and sensitive method to detect three catecholamines, isoprenaline, epinephrine, and dopamine, by CE coupled with direct luminol‐potassium periodate chemiluminescence (CL) detection is described. The conditions for CE separation and CL reaction were systematically optimized. Under the optimum conditions, the baseline separation of three catecholamines was achieved within 6.5 min. The LODs obtained in standard solution were 5.3 × 10–8 mol/L for isoprenaline, 4.7 × 10–8 mol/L for epinephrine, and 1.5 × 10–7 mol/L for dopamine. The RSD of the migration time and peak area were less than 1.8 and 3.6% (n = 5), respectively. The present method was applied to the determination of the dopamine in urine samples of cigarette smokers and nonsmokers. The results obtained indicate that there is a close relationship between the content of dopamine in human urine and the amount of cigarettes smoked daily; the level of dopamine in smokers is higher than in nonsmokers.
Analysis of substances to be used as internal standards in MEKC
Authors: Hasemann Phillip , ter Balk Marieke , Wätzig Hermann
Published: May 2007

The use of internal standards (ISs) improves the quantitative performance of CE. However, ISs chosen for use in CZE often cannot be used for micellar EKC (MEKC). Therefore 22 substances were investigated as potential ISs in MEKC. These substances were selected based upon a literature search. The substances were investigated using a method similar to the standard operating conditions for MEKC as recommended by S. Terabe. Furthermore, the migration time and the corrected migration time (kS) were determined for each substance to establish the migration position relative to other peaks in the electropherograms. A combination of eight substances, selected according to the obtained results (tm = 4 up to 12 min), was tested for practical benefit and applicability. The peak area precision was in the range of 0.8 and 1.2% (n = 60), and the peaks were well shaped for all the investigated substances. The selected substances covered a wide migration time window and therefore they can be regarded as suitable for future analysis at any required migration position.
Distribution of piperitone oxide stereoisomers in Mentha and Micromeria species and their chemical syntheses
Authors: Larkov Olga , Matasyoh Josphat C. , Dudai Nativ , Lewinsohn Efraim , Mayer Alfred A. , Ravid Uzi
Published: May 2007

Chiral GC–MS analyses of natural and synthetic trans‐ and cis‐piperitone oxide were performed on an Rt‐βDEX‐sm capillary column in order to clarify the stereochemistry of their enantiomeric forms. Only enantiomerically pure laevo‐rotatory piperitone oxides, (1S,2S,4S)‐trans‐piperitone oxide and (1S,2S,4R)‐cis‐piperitone oxide, were detected by chiral analyses of Micromeria fruticosa (L.) Druce and Mentha longifolia L. The occurrence of the cis‐ and trans‐piperitone oxides was dependent on the population of the species. In all cases (1S,2S,4S)‐trans‐piperitone oxide was detected together with (4S)‐piperitone, while (1S,2S,4R)‐cis‐piperitone oxide was detected together with (4R)‐piperitone in the plants analysed. The four stereoisomers of trans‐ and cis‐piperitone oxide were obtained by alkaline epoxidation of both (4R)‐ and (4S)‐piperitone. The formation of the 1,2‐epoxide can take place on either side of the 1,4‐substituted six‐membered ring. Racemization at C4 was observed under alkaline epoxidation reaction conditions due to keto‐enol tautomerism. Copyright © 2007 John Wiley & Sons, Ltd.
Expression and functional analysis of the cellular retinoic acid binding protein from silkworm pupae (Bombyx mori)
Authors: Wang Xue‐Jian , Chen Jian , Lv Zheng‐Bing , Nie Zuo‐Ming , Wang Dan , Shen Hong‐Dan , Wang Xue‐Dong , Wu Xiang‐Fu , Zhang Yao‐Zhou
Published: May 2007

Cellular retinoic acid binding protein (CRABP) is a member of intracellular lipid‐binding protein (iLBP), and closely associated with retinoic acid (RA) activity. We have cloned the CRABP gene from silkworm pupae and studied the interaction between Bombyx mori CRABP (BmCRABP) and all‐trans retinoic acid (atRA). The MTT assay data indicated that when BmCRABP is overexpressed in Bm5 cells, the cells dramatically resisted to atRA‐induced growth inhibition. Conversely, the cells were sensitive to atRA treatment upon knocking down the BmCRABP expression. Subcellular localization revealed that BmCRABP is a cytoplasm protein, even when treated with atRA, the CRABP still remained in the cytoplasm. These data demonstrated that the function of BmCRABP have an effect on the physiological function of atRA. J. Cell. Biochem. 102: 970–979, 2007. © 2007 Wiley‐Liss, Inc.