bluuebunny/crossref_metadata_2025 huggingface dataset:
APPROPRIATE SAMPLE SIZES FOR SELECTING THE POPULATION WITH THE LARGEST VALUE OF π FROM AMONG κ BINOMIAL POPULATIONS
Authors: Levy Kenneth J.
Published: August 2011

Bechhofer's (1954) procedure for selecting the population with the largest mean from among κ normal populations with known variances is discussed as it applies to the problem of selecting the population with the largest value of π from among κ binomial populations. Tables of appropriate sample sizes are provided and an example is discussed concerning their use in which one might wish to select such a population at a specified probability level.
THE ANALYSIS OF DECISION‐MAKING PERFORMANCE
Authors: Aitchison J. , Moore1 M. F.
Published: August 2011

In real life many decision‐makers are faced with a sequence of problems of a similar nature but with varying features. Their performance can be observed and analysed through the construction of performance simulation models. Such analysis must distinguish between decision statements which are true, normative, subjective and simulative, and also between simple, ordinal, relative, absolute and distributional forms of statement. Measures of discrepancy are suggested for different forms of decision statement and techniques of comparing models and constructing simulative systems are described.
INVARIANCE OF MULTIDIMENSIONAL CONFIGURATIONS
Authors: Poor David D. S. , Wherry Robert J.
Published: August 2011

A method of testing for significant relationships between multidimensional configurations is presented. The ‘index of invariance” is defined as the correlation between the inter‐point distances from one configuration and the corresponding inter‐point distances from a second configuration. Empirical distributions of the index are developed for varying numbers of points and dimensions. Fitting the Gram‐Charlier family of curves to these data, additional distributions of the index are estimated based on two parameters, namely, the number of points and the number of dimensions. Tables of significance are presented for the index in terms of the two parameters. Applications based on ordinal multidimensional scaling and other multivariate techniques are discussed.
A COMPARATIVE EVALUATION OF SEVEN SIMILARITY MODELS
Authors: Gregson R. A. M.
Published: August 2011

Seven models relating similarity in pairs of two‐dimensional stimuli are stated; three derive from distance measures and four from so‐called content models. The metatheoretical status of assumptions underlying the various models is outlined. Two experiments, one using Dot pattern stimuli and the other Brick Wall patterns, on 54 and 50 subjects respectively, were chosen for their relation to previously published work and analysed using all of the seven models. A normed distance model, which can be equivalently expressed as a content model but not as a Minkowski distance model, was found to be marginally superior to alternatives. Under some conditions the predictions of the alternative models are practically indistinguishable, but a Euclidean distance model is inferior in this context. Implications for scaling and modelling are noted.
A GENERAL UPPER BOUND ON THE VARIANCE OF THE WILCOXON‐MANN‐WHITNEY U‐STATISTIC FOR SYMMETRIC DISTRIBUTIONS WITH SHIFT ALTERNATIVES
Authors: Ury Hans K. , Wiggins Alvin D.
Published: August 2011

Using Johnson's (1975) sharp upper bound on the variance of the Wilcoxon‐Mann‐Whitney U‐statistic for the case of continuous symmetric distributions and shift alternatives, an upper bound depending only on the sample sizes is obtained for this case. The new bound is smaller than the corresponding bound given by van Dantzig (1951) for a more general model. The decrease is smallest for equal sample sizes, in which case it ranges from 16 to 29 percent as the sample sizes increase.
A progressive approach to non‐additivity and genotype‐environmental covariance in the analysis of human differences
Authors: Eaves L. J. , Last Krystyna , Martin N. G. , Jinks J. L.
Published: August 2011

No aspect of human behaviour genetics has caused more confusion and generated more obscurantism than the analysis and interpretation of the various typos of non‐additivity and non‐independence of gene and environmental action and interaction—genotype—environment interaction and covariation, dominance and assortative mating. A comprehensive framework of theory and method is outlined in which these and other contributions to individual differences can be critically assessed.
A theory of the visual illusions
Authors: Watson Alistair I.
Published: August 2011

An attempt is made to explain the geometric illusions by assuming that ‘visual’ space is non‐Euclidean, and that the departure from Euclidean geometry is the result of the interaction between the elements within the ‘visual’ space. The interaction is represented by a metric equation, and, by assuming that the subjective judgements are made on the basis of a context‐dependent geometry given by the metric equation, explicit expressions for some of the well‐known illusions are derived. Experimental data are presented and reviewed to evaluate the validity of the explanation.
Effects of type of movement on the temporal precision of response sequences
Authors: Wing Alan M.
Published: August 2011

The negative covariation between adjacent interresponse intervals (lag‐one autocovariance) observed when people make repetitive responses can be accounted for by a model that postulates two independent processes of timekeeping and response generation (Wing & Kristofferson, 1973b). The present paper considers generalizations of this model that assume certain simple types of dependence either among the timekeeper intervals or among the response delays. It is shown that these may be distinguished on the basis of the interresponse‐interval autocovariance function. An experiment is described that contrasts the use of four different types of movement bringing the index finger into repeated contact with a response plate at 400 msec intervals. While the data reject the original formulation of the two‐process model they are consistent with the generalized version in which there is dependence of successive response delays in the form of a first‐order autoregressive process.
An evaluation of some non‐parametric and parametric tests for multiple comparisons
Authors: Keselman H. J. , Rogan Joanne C.
Published: August 2011

The Kruskal & Wallis and normal scores non‐parametric multiple comparison tests were compared to the parametric Tukey test. In addition to quantifying and manipulating the degree of heterogeneity due to combining heterogeneous variances with unequal sample sizes, the tests were compared for their sensitivity, as well as rates of Type I error, under varying conditions of mean variability when sampling from normal and exponential distributions. It was found that the Kruskal & Wallis test is always preferable to the normal scores test while the choice between the Kruskal & Wallis and Tukey tests depends upon sample size, population shape and mean variability.
The indeterminacy of components and the definition of common factors
Authors: McDonald Roderick P.
Published: August 2011

Results given by Sohönemann & Steiger (1976) are related to theory given by McDonald (1975) and McDonald & Burr (1967). From the relation between split‐half estimators of a common factor, it is shown that the factor is uniquely defined in a behaviour domain by a set of marker variables, if it is defined by them at all. Regression components obtained from split‐halves do not, in general, have higher correlations than factor score estimators, hence there is no reason to prefer regression components to common factors on grounds of determinacy.
Multiple regression and poorly conditioned matrices
Authors: Maxwell A. E.
Published: August 2011

The way in which poorly conditioned matrices can adversely affect the stability of estimates of partial regression coefficients is described. It is noted that in the absence of measurement error in the independent variables relative stability can be achieved by the ‘ridge regression’ method, but when the margin of error is considerable, as is generally the case in social science research, poorly conditioned matrices of an extreme kind occur only infrequently. Whether or not they occur the method of estimating regression coefficients which employs the basic model of factor analysis effectively circumvents inherent difficulties.
The randomized response technique and appropriate sample sizes for selecting the population with the largest value of π from among k binomial populations
Authors: Levy Kenneth J.
Published: August 2011

A table of appropriate sample sizes is provided for selecting the population with the largest value of π from among k binomial populations when estimation involves the randomized response technique. The determination of these sample sizes is based upon a variance stabilizing transformation suggested by Levy (19766). The entries in the present table are larger than corresponding entries in tables associated with estimation which involves the more conventional method of direct questioning. The results of a Monte Carlo study are also provided in support of the sample sizes presently being proposed.
Conditional maximum‐likelihood estimation for a multiplicative binominal response model
Authors: Douglas Graham A.
Published: August 2011

The conditional maximum‐likelihood estimates for a binomial logistic latent trait model are derived and examined. A computing algorithm is used to make a comparison between the conditional estimates and a set of unconditional estimates. The general conclusion is that there may be data sets for which significant discrepancies will occur between conditional and unconditional approaches to the estimation of the item parameters.
The analysis of variance in experimental psychology: 1934–1945
Authors: Lovie A. D.
Published: August 2011

The paper provides a survey of early applications of analysis of variance in psychology, concentrating on experimental psychology, but with one or two brief excursions into educational psychology. The work demonstrates that incorporating the technique into psychology was a long and painful process. This was due more to the substantive implications of the method than to the purely practical matters of increased arithmetical labour and novelty of language that the new technique brought with it. Such a view differs radically from that expressed by commentators working during the period covered by the paper and later. Finally, a brief account of how experiments were conducted and analysed prior to analysis of variance is provided so as to point up the sources of difficulty with the method. A special section is devoted to early attempts to cope with the concept of interaction.
Factor analysis of multiple batteries by maximum likelihood
Authors: Browne M. W.
Published: August 2011

McDonald's (1970) generalization of Tucker's (1958) inter‐battery factor analysis model to multiple batteries is considered. The identification of parameters is examined and an iterative algorithm for obtaining maximum‐likelihood estimates is provided. Consideration of the relationship between inter‐battery factor analysis and canonical correlation analysis in the case of two batteries suggests a generalization of canonical coefficients to the situation where there are several batteries. Examples of the application of the procedure are given.
Complex social decision scheme models
Authors: Gillett Raphael
Published: August 2011

Expressions are developed for the probability that a group chooses a particular course of action in each of four complex social decision scheme models: majority with proportionality, majority with equiprobability, plurality with proportionality and plurality with equiprobability. A method of discriminating by experiment among a number of social decision scheme models is suggested involving, where feasible, experimenter manipulation of individual member preference probabilities.
Describing and analysing constant‐error patterns in psychophysical interpolation
Authors: MacRae A. W.
Published: August 2011

A simple technique is proposed for the description and analysis of the patterns of error customarily found in tasks requiring subjects to interpolate between explicit or implicit reference values. The error patterns can be characterized by two parameters. One parameter reflects any consistent tendency to make positive or negative errors overall while the other reflects the difference in error between the two halves of the interpolation interval. The style of analysis advocated is quantitatively descriptive of the error patterns and leads to a simplification of subsequent statistical analysis of the results.
A tandem random walk model for psychological discrimination
Authors: Heath Richard A.
Published: August 2011

A random walk model for decision making in psychological discrimination tasks is described which provides a satisfactory account of the observed non‐stationarity of the representation of stimulus information. The model successfully predicts the relationship between RT and response proportion in a temporal order judgement task performed under instructions emphasizing both speed and accuracy. The implications of the model for memory‐dependent tasks are discussed.
A note on estimating interscale relations in ‘direct’ psychophysical scaling
Authors: Wegener Bernd , Kirschner Hans‐Peter
Published: August 2011

The aim of this paper is twofold: Firstly, a mathematical procedure is described for estimating interscale relations between category and magnitude scales. The computer program based on this procedure is designed for replacing ad hoc techniques that are widely employed in exploring between‐scale relations. Secondly, the new method is applied to empirical data from a large‐scale survey, and a range‐dependent model for the category‐magnitude relation is proposed.
A statistical paradigm to evaluate homogeneity within subjects and within tasks
Authors: Gliner Gail S.
Published: August 2011

A statistical paradigm proposed by Hubert et al. (1981) for evaluating the pattern of cross‐classified proximity data can be used to assess homogeneity between responses for the same subjects on two different tasks, and conversely, for the same tasks over different subjects. The paradigm involves ‘blocking’ on one variable while evaluating the effects of the second. As an example using a similarity rating task and a sorting task on the same animal names, the increase of within subject and within task correlations was confirmed.
Monotonic measures of agreement for ranked data
Authors: Stavig Gordon R.
Published: August 2011

The τb and y statistics are interpreted as rank‐monotonic coefficients of partial agreement. Using a method of transposition employed by Pearson's ri intraclass correlation coefficient, the τbi and yi intraclass coefficients of total monotonic agreement are created. Transpositional measures of agreement like τbi and τi measure the combined effects of cell and marginal disagreement which make them particularly suitable for reliability studies. The coefficients are also made applicable to K > 2 sets of ranks.
Foundations of factor analysis: Some practical implications
Authors: Bartholomew D. J.
Published: August 2011

The paper discusses some practical implications of a new approach to factor analysis expounded in Bartholomew (1984). The problem with which it deals may be posed in the following way. Given p variables measured on n individuals, to find one or more functions of these variables which, in some sense, effectively summarize what is common to the larger set. It was shown in the earlier paper that, under fairly general conditions, such a summarization can efficiently be achieved by linear functions of the manifest variables. Here, the consequences of this result are explored in relation to such matters as rotation of axes, factor scores, non‐linear and hierarchical factor analysis.

The conclusion reached is that while almost all of the existing numerical methods relating to the estimation of factor models remain relevant, the presentation and interpretation of the results is substantially modified. In particular, the focus is shifted from unobservable factors to observable functions of the data and the distinction between orthogonal and oblique rotations has no significance.
Analysis of variance versus randomization tests—a comparison
Authors: Bradbury Ian
Published: August 2011

Following the discussion by Still & White (1981), an investigation of the properties of approximate randomization tests used in place of analysis of variance is presented.

Errors in Still & White have been corrected and explanations are offered for some of the consequent discoveries. As a result of this, more reserved conclusions about the power of the approximate randomization test relative to the usual F test are made.
A comparison of the power of the t test, Wilcoxon's test, and the approximate permutation test for the two‐sample location problem
Authors: van den Brink Wulfert P. , van den Brink Sebastiaan G. J.
Published: August 2011

Simulations were performed to compare the power of the approximate permutation test with the power of t test and Wilcoxon's test for the two‐sample location problem under a shift model. The approximate permutation test is sometimes suggested as a panacea for non‐normality. However, for the distributions and sample sizes used in this study, the power of the approximate permutation test and the t test are nearly equal. Under non‐normality Wilcoxon does have better power characteristics than the other tests. So it can be concluded, that in this study Wilcoxon, a permutation test on ranks, does perform better under non‐normality than the approximate permutation test that uses the measurements themselves.
A random utility family that includes many of the ‘classical’ models and has closed form choice probabilities and choice reaction times
Authors: Marley A. A. J.
Published: August 2011

A large class of random utility models can be expressed in terms of multivariate (dependent) Weibull distributions. This class includes Luce's choice model, McFadden's generalized extreme value class, and Tversky's elimination by aspects model. A major advantage of this class is that one can obtain simple closed form representations of the predicted choice probabilities and reaction times. In this paper I develop a ‘process’ model that gives a natural interpretation of the origins of these models, and discuss various limitations, and possible extensions, of such models.
Multiple‐group structural modelling with non‐normal continuous variables
Authors: Muthén Bengt
Published: August 2011

An estimator is considered for mean and covariance structure analysis of non‐normal continuous variables. This estimator extends the ADF estimator of Browne (1982, 1984) to include structured means. The behaviour of the estimator is compared to that of normal‐theory generalized least‐squares in simulated data.
Variants of chi‐square for 2 × 2 contingency tables
Authors: Richardson John T. E.
Published: August 2011

Four variants of the chi‐square statistic are evaluated in terms of their adequacy as tests of association in 2 × 2 contingency tables. When both sets of marginal totals are fixed in advance, none of these variants is wholly satisfactory, even with moderately large samples. When one set of marginal totals is fixed in advance while the other is free to vary, or when neither set of marginal totals is fixed in advance, a variant of chi‐square proposed by Upton (1982) is to be preferred both theoretically and in practice. The variant proposed by Yates (1934) which incorporates a correction for continuity and which is often recommended in statistics textbooks is theoretically unsound, shows an extremely conservative bias, and lacks sufficient power.
Statistical modelling of one‐mode and two‐mode networks: Simultaneous analysis of graphs and bipartite graphs
Authors: Wasserman Stanley , Iacobucci Dawn
Published: August 2011

A bipartite graph, in which the nodes (or actors in a social network) are partitioned into two sets, can be studied using recent statistical models for dyadic interactions. These models, which are loglinear for the probabilities of dyadic choices or interactions, allow not only arcs or relationships to exist between the sets but also within the sets. Thus, the methods described here are applicable not only to bipartite graphs, consisting of arcs existing between nodes in different sets, but also to directed graphs that are defined within the two sets of nodes. Data on both types of graphs can be analysed simultaneously.

A bipartite graph has an adjacency matrix (or sociomatrix) with two ‘modes’. The set of nodes in the row mode differs from the set of nodes in the column mode. For example, in marketing, one could study the dyadic relations in a ‘buyers‐by‐sellers’ network. Generally, the relations observed in a one‐mode network, which has a square sociomatrix (row mode = column mode) are bidirectional—the actors indexing the columns may also ‘relate to’ the actors indexing the rows. The relations observed in a two‐mode network are generally unidirectional—the row actors relate to or choose the column actors, but the column actors do not relate to the row actors. Referring to our example, a buyer might pay a seller for some item, but a seller would not pay a buyer.

Statistical models for the separate analysis of these one‐mode and two‐mode matrices are extended in this paper to the simultaneous analysis of both types of networks. A superordinate one‐mode sociomatrix is created in which the rows and columns consist of all actors (that is, all buyers and sellers). This larger matrix contains both the one‐mode matrices and the two‐mode matrices. Multivariate analysis of unidirectional and bidirectional relations in social networks and complex directed graphs becomes possible with this simultaneous consideration of both types of matrices.
Type I error and the number of iterations in Monte Carlo studies of robustness
Authors: Robey Randall R. , Barcikowski Robert S.
Published: August 2011

A recent survey of simulation studies concluded that an overwhelming majority of papers do not report a rationale for the decision regarding the number of Monte Carlo iterations. A surprisingly large number of reports do not contain a justifiable definition of robustness and many studies are conducted with an insufficient number of iterations to achieve satisfactory statistical conclusion validity. The implication is that we do not follow our own advice regarding the management of Type I and Type II errors when conducting Monte Carlo experiments. This paper reports a straightforward application of a well‐known procedure for the purpose of objectively determining the exact number of iterations necessary to confidently detect departures from robustness in Monte Carlo results. A table of the number of iterations necessary to detect departures from a series of nominal Type I error rates is included.
On statistical inference with parameter estimates on the boundary of the parameter space
Authors: Dijkstra T. K.
Published: August 2011

Inadmissible estimates, like negative variance estimates, frequently occur when a theoretical covariance matrix is fitted to a sample covariance matrix. When this happens, it is common practice to re‐estimate subject to non‐negativity constraints and to count the ensuing zeros as true zeros. We derive conditions under which this approach has a valid frequentist interpretation.
Validity of the chi‐square test in dichotomous variable factor analysis when expected frequencies are small
Authors: Reiser Mark , VandenBerg Maria
Published: August 2011

This paper presents a comparison of results from two methods for estimating and testing a model for the factor analysis of dichotomous variables. For k manifest dichotomous variables, the data can be cross‐classified to form a vector of 2k frequencies, and nonlinear methods that use the full information in these 2k frequencies are available for factor analysis. In addition, another method that uses only the limited information in the first‐, and second‐order marginal frequencies is available for the same model. As k becomes larger, substantial differences between the full‐information and limited‐information methods become apparent in results from the test of fit. For large k. Type I and Type II error rates may be higher in the full‐information approach, because as the vector of 2k frequencies becomes sparse, the chi‐square approximation for the distribution of the goodness‐of‐fit test statistic becomes poorer. In this paper, Monte Carlo experiments are used under a variety of conditions to compare the methods for rate of Type I errors when the model matches the simulated data and for the rate of Type II errors when the model does not match the simulated data.
A regression smoother for resistant measures of location and scale
Authors: Wilcox Rand R.
Published: August 2011

There are a variety of exploratory and informal graphical methods for studying the relationship between two random variables, many of which offer some resistance to outliers or unusual values. Some of these are extremely flexible when considering how the mean of Y might be related to some other random variable, X. However, when interest is focused on a resistant measure of location, such as the trimmed mean or a robust M‐estimator of location, the choice of methods is considerably reduced, and some of the more obvious procedures can fail. When dealing with how a measure of scale associated with Y varies as a function of X, even fewer methods arc available. This paper suggests a simple exploratory procedure that can be used to study how any parameter associated with Y varies as a function of Moreover, this is done without imposing any restrictions on what the relationship might be. The method might be used to suggest an appropriate transformation of the data, to summarize data without imposing any parametric restrictions, and in some cases the method suggests pursuing an investigation where more standard techniques (correlation and least squares regression) suggest that there is nothing interesting in the data. This latter feature is illustrated with data from a study on when a child utters its first word.
Information processing in similarity judgments
Authors: Barthélemy J.‐P. , Mullet E.
Published: August 2011

To account for expert information processing of similarity judgments on objects characterized by several attributes, a flexible model, inspired by works of Montgomery (1983) and Barthélemy & Mullet (1986, 1992) is presented and illustrated on the basis of data collected from experienced subjects. This model coordinates three types of rules: threshold rules, conjunctive rules and disjunctive rules. It is based on the principle that a ‘bounded consensus rule’ is the major rule and that all others are merely employed to obtain a consensus structure quickly. Three basic principles are incorporated in the model: (i) a parsimony principle, (ii) a reliability principle, (iii) a decidability principle. The model can be represented as a process (flowchart) or as a formula (equation).
Testing hypotheses about working memory capacity
Authors: Gillett Raphael
Published: August 2011

When an individual is engaged in sampling from a finite population, an assessment of their working memory for previously sampled objects is often desired. An extension of the classical occupancy distribution provides a framework for testing hypotheses about working memory capacity, based on a general model of working memory in which the individual retains a record of m previous inspections (and hence does not make the mistake of resampling these objects) and samples with replacement objects outside the current memory set. The buffer size m provides a common metric for assessing the effect of variables on performance in search tasks involving different numbers of items, or locations.
Test of linear trend in eigenvalues of a covariance matrix with application to data analysis
Authors: Bentler P. M. , Yuan Ke‐Hai
Published: August 2011

Principal component analysis and factor analysis are the most widely used tools for dimension reduction in data analysis. Both methods require some good criterion to judge the number of dimensions to be kept. The classical method focuses on testing the equality of eigenvalues. As real data hardly have this property, practitioners turn to some ad hoc criterion in judging the dimensionality of their data. One such popular method, the ‘scree test’ or ‘scree plot’ as described in many texts and statistical programs, is based on the trend in eigenvalues of sample covariance (correlation) matrix. The principal components or common factors corresponding to eigenvalues which exhibit a slow linear decrease arc discarded in further data analysis. This paper develops a formal statistical test for the ‘scree plot’. A special case of this test is the classical test for equality of eigenvalues which has been suggested in several texts as the criterion to decide the number of principal components to retain. Comparisons between equality of eigenvalues and the slow linear decrease in eigenvalues on some classical examples support the hypothesis of slow linear decrease. A physical background to such a phenomenon is also suggested.
Saturated models for repeated measures
Authors: Bechtel Gordon G. , Khuri André I.
Published: August 2011

Psychological and physiological data often consist of correlated responses repeatedly taken from the same sample of individuals. The unknown covariances among these responses present a problem for statistical inference to parameters of the population from which the samples are drawn. The present paper addresses this problem for saturated mean response models, i.e. models in which parameters and mean responses are equal in number. In these models the unknown covariances among repeated measures, which are nuisance parameters, are shown to cancel out. This cancellation provides exact tests and estimates for parameters within and between groups by means of Wishart distribution theory. These tests and estimates are illustrated for three different types of repeated measures, each involving a saturated mean response model. The unknown covariances in saturated models are also discussed in relation to the structured covariances in random coefficient models.
Testing continuous moderators in meta‐analysis: A comparison of procedures
Authors: Sánchez‐Meca Julio , Marín‐Martínez Fulgencio
Published: August 2011

Using Monte Carlo simulation, we compare the statistical power and Type I error rates of three procedures commonly applied in meta‐analysis to detect the influence of a continuous moderator variable on the estimated effect sizes from a set of independent primary studies. We use the conventional T test (TTEST), the Hedges & Olkin (1985) zHO test (H&O), and the Rosenthal & Rubin (1982) zRR test (R&R). The H&O and R&R procedures weight every estimated effect size by its inverse‐variance, whereas in the conventional T test the individual effect sizes are unweighted. Results show an adequate control of the Type I error rate for the three procedures in all of the conditions. The statistical power is very similar in the H&O and R&R procedures, and systematically lower in the conventional T test. Both H&O and R&R procedures were similarly the most appropriate and powerful to detect a quantitative moderator variable on effect sizes, supporting the suitability of applying weighting schemes in meta‐analysis.
Reliability of gain scores under realistic assumptions about properties of pre‐test and post‐test scores
Authors: Zimmerman Donald W. , Williams Richard H.
Published: August 2011

For many years, psychometricians working in the context of classical test theory have questioned the reliability of measures of gains and growth. Many tables and figures in textbooks and journal articles have suggested that the reliability of these measures is far below that of the pre‐test and post‐test scores from which they are determined. Previous findings reported by the present authors have shown that under special conditions, gain scores can be much more reliable, especially when variances of pre‐test and post‐test scores are unequal and at the same time the reliability coefficients of pre‐test and post‐test scores are unequal with the same directionality. The present paper explores a novel approach to derivation of formulae for the reliability of gain scores in classical test theory. This approach reveals not only that gain scores can be reliable, but also that their reliability coefficients are intermediate between those of the pre‐test and the post‐test in a large proportion of practical testing applications.
The Life and Legacies of a Polymath

G. Evelyn Hutchinson and the Invention of Modern Ecology
by Nancy G. Slack

Yale University Press, New Haven, CT, 2010. 475 pp. $40, £30. ISBN 9780300161380.
Authors: Rosenzweig Michael L.
Published: August 2011

Slack explores the many facets of the life and science of G. Evelyn Hutchinson and his fundamental contributions to modern ecology.
Seasonal Flows on Warm Martian Slopes
Authors: McEwen Alfred S. , Ojha Lujendra , Dundas Colin M. , Mattson Sarah S. , Byrne Shane , Wray James J. , Cull Selby C. , Murchie Scott L. , Thomas Nicolas , Gulick Virginia C.
Published: August 2011

Rare meter-scale slope features on Mars might be explained by transient flows of liquid salty water.
Effects of Working-Memory Training on Striatal Dopamine Release
Authors: Bäckman Lars , Nyberg Lars , Soveri Anna , Johansson Jarkko , Andersson Micael , Dahlin Erika , Neely Anna S. , Virta Jere , Laine Matti , Rinne Juha O.
Published: August 2011

A cognitive training program that improves working memory is associated with increased dopamine release during task performance.
Extending the Carbon Chain: Hydrocarbon Formation Catalyzed by Vanadium/Molybdenum Nitrogenases
Authors: Hu Yilin , Lee Chi Chung , Ribbe Markus W.
Published: August 2011

The molybdenum nitrogenase enzyme can reduce carbon monoxide, albeit inefficiently, in addition to its native substrate, nitrogen.
Progress Toward Development of a Hepatitis C Vaccine with Broad Shoulders
Authors: Ray Ranjit
Published: August 2011

A rational, mechanism-based design of vaccine immunogens may be capable of eliciting potent, broadly neutralizing antibodies against HCV.
Comparison of a New Multiplex Binding Assay versus the Enzyme-Linked Immunosorbent Assay for Measurement of Serotype-Specific Pneumococcal Capsular Polysaccharide IgG
Authors: Goldblatt David , Ashton Lindsey , Zhang Yuhua , Antonello Joseph , Marchese Rocio D.
Published: August 2011

The measurement of serotype-specific anti-capsular polysaccharide antibodies remains the mainstay of pneumococcal (Pn) vaccine evaluation. New methods that allow the simultaneous measurement of antibodies to several antigens in small volumes of serum, and that agree well with existing techniques, are urgently required to support the increasing number of concomitant vaccines delivered in the infant immunization schedules and the use of extended-valency Pn vaccines. We therefore compared a relatively new multiplexed platform for measuring anti-Pn antibodies with the existing WHO consensus enzyme-linked immunosorbent assay (ELISA). A panel of 50 pediatric samples (34 collected after receipt of a heptavalent pneumococcal conjugate vaccine [PCV7] and 16 without PCV7) was analyzed across two different laboratories using a new multiplex electrochemiluminescence (ECL)-based detection assay developed for the quantitation of IgG serotype-specific antipneumococcal antibodies, and the results were compared to those obtained using the WHO consensus ELISA. For the seven serotypes measured, there was good agreement between the techniques and laboratories. The most notable difference was found between the ECL assay and the ELISA: concentrations tended to be higher in the ECL assay. For serotypes 6B, 9V, 18C, and 23F, the average increases in concentration ranged from 48 to 102%. However, the agreement rates on the proportions of samples with concentrations surrounding 0.35 μg/ml were >82% for all serotypes tested. Agreement between the two laboratories running the ECL assay was generally good: agreement on proportions of samples with concentrations surrounding 0.35 μg/ml was in excess of 92%, and agreement on average antibody concentrations was within 31%. We conclude that the Meso Scale Discovery (MSD) platform provides a promising new technique for the simultaneous measurement of antipneumococcal antibodies.
Evaluation of Six Commercial Nucleic Acid Amplification Tests for Detection of Neisseria gonorrhoeae and Other Neisseria Species
Authors: Tabrizi Sepehr N. , Unemo Magnus , Limnios Athena E. , Hogan Tiffany R. , Hjelmevoll Stig-Ove , Garland Susanne M. , Tapsall John
Published: August 2011

Molecular detection of
Neisseria gonorrhoeae
in extragenital samples may result in false-positive results due to cross-reaction with commensal
Neisseria
species or
Neisseria meningitidis
. This study examined 450 characterized clinical culture isolates, comprising 216
N. gonorrhoeae
isolates and 234 isolates of nongonococcal
Neisseria
species (
n
= 218) and 16 isolates of other closely related bacteria, with six commercial nucleic acid amplification tests (NAATs). The six NAATs tested were Gen-Probe APTIMA COMBO 2 and APTIMA GC, Roche COBAS Amplicor CT/NG and COBAS 4800 CT/NG tests, BD ProbeTec GC Qx amplified DNA assay, and Abbott RealTime CT/NG test. All assays except COBAS Amplicor CT/NG test where four (1.9%) isolates were not detected showed a positive result with all
N. gonorrhoeae
isolates (
n
= 216). Among the 234 nongonococcal isolates examined, initial results from all assays displayed some false-positive results due to cross-reactions. Specifically, the COBAS Amplicor and ProbeTec tests showed the highest number of false-positive results, detecting 33 (14.1%) and 26 (11%) nongonococcal
Neisseria
isolates, respectively. On the first testing, APTIMA COMBO 2, APTIMA GC, Abbott RealTime, and Roche COBAS 4800 showed lower level of cross-reactions with five (2.1%), four (1.7%), two (1%), and two (1%) of the isolates showing low-level positivity, respectively. Upon retesting of these nine nongonococcal isolates using freshly cultured colonies, none were positive by the APTIMA COMBO 2, Abbott RealTime, or COBAS 4800 test. In conclusion, the COBAS Amplicor and ProbeTec tests displayed high number of false-positive results, while the remaining NAATs showed only sporadic low-level false-positive results. Supplementary testing for confirmation of
N. gonorrhoeae
NAATs remains recommended with all samples tested, in particular those from extragenital sites.
NMR crystallography — Three polymorphs of phenobarbital
Authors: Abraham Anuji , Apperley David C. , Gelbrich Thomas , Harris Robin K. , Griesser Ulrich J.
Published: August 2011

The NMR spectra of polymorphs I, II, and III of the pharmaceutical drug compound phenobarbital are discussed in relation to the crystal structures. Whilst some features can be explained by inspection of the structures, others require more detailed work. In this paper, shielding computations for the 13C, 15N, and 1H nuclei using crystallographic repetition (with optimization of the positions of all atoms) are presented. These have enabled the majority of the signals to be assigned with some confidence and several features of NMR crystallography are illuminated. In particular, resonances have been attributed separately for the three independent molecules of form I (and also for form II). Moreover, the chemically equivalent but crystallographically distinct nuclei forming the two halves of the phenyl ring (and likewise of the heteronuclear ring) have been distinguished and a structural conformational motif attached to the 15N chemical shifts revealed. The small differences between the spectra of forms I and II (which have very closely related crystal structures) are well-reproduced. The value of computations for establishing precise assignments of signals to crystallographic sites of atoms is emphasised. Conversely, the work provides a good test of the accuracy of computations for crystalline materials.
Effects of dopamine depletion on information flow between the subthalamic nucleus and external globus pallidus
Authors: Cruz Ana V. , Mallet Nicolas , Magill Peter J. , Brown Peter , Averbeck Bruno B.
Published: August 2011

Abnormal oscillatory synchrony is increasingly acknowledged as a pathophysiological hallmark of Parkinson's disease, but what promotes such activity remains unclear. We used novel, nonlinear time series analyses and information theory to capture the effects of dopamine depletion on directed information flow within and between the subthalamic nucleus (STN) and external globus pallidus (GPe). We compared neuronal activity recorded simultaneously from these nuclei in 6-hydroxydopamine-lesioned Parkinsonian rats with that in dopamine-intact control rats. After lesioning, both nuclei displayed pronounced augmentations of beta-frequency (∼20 Hz) oscillations and, critically, information transfer between STN and GPe neurons was increased. Furthermore, temporal profiles of the directed information transfer agreed with the neurochemistry of these nuclei, being “excitatory” from STN to GPe and “inhibitory” from GPe to STN. Separation of the GPe population in lesioned animals into “type-inactive” (GP-TI) and “type-active” (GP-TA) neurons, according to definitive firing preferences, revealed distinct temporal profiles of interaction with STN and each other. The profile of GP-TI neurons suggested their output is of greater causal significance than that of GP-TA neurons for the reduced activity that periodically punctuates the spiking of STN neurons during beta oscillations. Moreover, STN was identified as a key candidate driver for recruiting ensembles of GP-TI neurons but not GP-TA neurons. Short-latency interactions between GP-TI and GP-TA neurons suggested mutual inhibition, which could rhythmically dampen activity and promote anti-phase firing across the two subpopulations. Results thus indicate that information flow around the STN-GPe circuit is exaggerated in Parkinsonism and further define the temporal interactions underpinning this.
Comparison of Nephrostomy Drainage Types following Percutaneous Nephrolithotomy Requiring Multiple Tracts: Single Tube versus Multiple Tubes versus Tubeless
Authors: Resorlu Berkan , Kara Cengiz , Sahin Erhan , Unsal Ali
Published: August 2011

Objectives: Placement of multiple nephrostomy tubes is the standard practice after completion of multitract percutaneous nephrolithotomy (PCNL) to reduce hemorrhage and urinary extravasation.We compared the outcomes among tubeless, single nephrostomy drainage and multiple nephrostomy drainage tubes following PCNL requiring multiple tracts. Methods: We retrospectively analyzed the data of 115 patients who underwent PCNL using multiple (two or more) access tracts. Patients were categorized into three groups: one nephrostomy tube for each tract (group 1, n = 43); single nephrostomy tube placement (group 2, n = 51), and no nephrostomy drainage with antegrade placement of a double-J stent (group 3, n = 21). Results: The three groups had comparable demographic data. The differences in operative times, average hemoglobin decrease and complication rates for the three groups were not statistically significant. The average hospital stay in the tubeless group (mean 2.1 days) was significantly shorter than that in group 1 (4.2 days) and group 2 (3.5 days). The postoperative analgesic requirement was significantly higher in group 1 compared to group 2 (p < 0.05) and group 3 (p <0.001). Stones were completely cleared in 83.7, 84.3 and 85.7% of patients, which increased to 90.7, 92.1, and 95.2% with adjunctive therapies in groups 1, 2 and 3, respectively. Conclusions: Single or no nephrostomy drainage following multitract PCNL offers the potential advantages of decreased postoperative analgesic requirement, and hospital stay without increasing the complications.
Impact of Sleep Position on Stone Clearance after Shock Wave Lithotripsy in Renal Calculi
Authors: Ziaee Seyed Amir Mohsen , Hosseini Seyed Reza , Kashi Amir H. , Samzadeh Mohammad
Published: August 2011

Objectives: We evaluated the impact of sleep position on the effectiveness of shock wave lithotripsy (SWL) in renal calculi. Patients and Methods: Patients (n = 120) with a single radiopaque renal stone who were candidates for SWL were enrolled. For studying patients’ position during sleep, a novel sleep position recorder was designed. Group 1 (n = 60) consisted of patients who slept preferentially on the ipsilateral side of the stone; group 2 (n = 60) comprised patients who slept preferentially on the contralateral side. Treatment effectiveness was defined as the absence of residual stones >3 mm up to 3 months after SWL. Results: The mean (range) percent of sleep on the ipsilateral side of the stone was 61.5% (51–78) and on the contralateral side it was 62.4% (51–81) in groups 1 and 2, respectively (p > 0.05). The overall success rate of SWL was 88.3% (77.4–95.2) and 70.0% (56.8–81.2) in groups 1 and 2, respectively (p = 0.01). Stone clearance increased with an increasing percent of total sleep time on the ipsilateral side of the kidney stone (p = 0.045). Conclusions: The percent of stone-free patients was higher in the group of patients who slept ipsilaterally relative to the kidney stone compared with patients who slept on the contralateral side.
Simultaneous Correction of Anterior and Apical Vaginal Prolapse with the Modified Placement of the Transobturator-Guided Mesh (Anterior ProliftTM) Set
Authors: Ignjatovic Ivan , Stojkovic Ivica , Stankovic Jablan , Basic Dragoslav , Potic Milan , Ignjatovic Biserka
Published: August 2011

Aim: Modified placement of the Anterior Prolift™ (MODAP) in patients with prolapse of the anterior and middle vaginal compartment is described. It was performed in order to achieve simultaneous tension-free correction of the anterior and middle vaginal compartment without excessive use of the mesh. Material and Methods: MODAP was performed in 32 patients. The anterior part of the mesh was placed transobturatorily. Surplus of the central part of the mesh was longitudinally divided and fixed around the cervix. Posterior mesh arms were passed through the sacrospinous ligament. All patients were analyzed regarding anatomy and symptoms 1 year after surgery. Results: Cure of pelvic organ prolapse was achieved in 28 of 32 (87.5%) patients. The position of Ba and C points was significantly corrected (p = 0.00). Deterioration of the posterior compartment occurred in 1 case. Symptoms of pelvic organ prolapse were significantly corrected (p = 0.05 up to p = 0.00) except for rectal emptying. Conclusion: MODAP makes an improvement of both anatomy support and symptoms in cases with mixed insufficiency of the anterior vaginal wall and apical vaginal support.
Functional Genomics of Tick Thioester-Containing Proteins Reveal the Ancient Origin of the Complement System
Authors: Buresova Veronika , Hajdusek Ondrej , Franta Zdenek , Loosova Gabriela , Grunclova Lenka , Levashina Elena A. , Kopáček Petr
Published: August 2011

Ticks are important ectoparasites and vectors of multiple human and animal diseases. The obligatory hemophagy of ticks provides a formidable route for parasite transmission from one host to another. Parasite survival inside the tick relies on the ability of a pathogen to escape or inhibit tick immune defenses, but the molecular interactions between the tick and its pathogens remain poorly understood. Here we report that tick genomes are unique in that they contain all known classes of the α2-macroglobulin family (α2M-F) proteins: α2-macroglobulin pan-protease inhibitors, C3 complement components, and insect thioester-containing and macroglobulin-related proteins. By using RNA interference-mediated gene silencing in the hard tick Ixodes ricinus we demonstrated the central role of a C3-like molecule in the phagocytosis of bacteria and revealed nonredundant functions for α2M-F proteins. Assessment of α2M-F functions in a single organism should significantly contribute to the general knowledge on the evolution and function of the complement system. Importantly, understanding the tick immune mechanisms should provide new concepts for efficient transmission blocking of tick-borne diseases.