bluuebunny/crossref_metadata_2025 huggingface dataset:
The role of the marketing function in operations of a construction enterprise: misconceptions and paradigms
Authors: Cicmil Svetlana , Nicholson Andrew
Published: May 2004

Elaborates on specific realities of the construction environment, and of management and operations of growing construction enterprises. Presents a case study looking particularly at entrepreneurial attitudes towards the marketing function in the sector, and illuminates the areas of “misfit” between modern business philosophy and traditional “engineers paradigm”. Offers some lessons to entrepreneurial managers/owners on how to reap benefits of marketing orientation by replacing the inherent inward‐oriented management attitudes with increased understanding of the complex and changing construction environment, clients’ expectations and sources of competition. Offers scope for further discussion on the role of the marketing function in the development of entrepreneurial construction companies in the UK and abroad.
All roads lead to ROM: the role of CD‐ROM in emerging education delivery systems
Authors: Williams Tarrnie
Published: May 2004

Looking to the future, this article presents the argument that of two principal interactive technologies currently vying for primary use in education, video disc and CD‐ROM, it is the latter that will emerge as the better option once the dust has settled. The case is examined in the context of entertainment and education, the information highway, and integrated learning systems.
Marketing science in a postmodern world: introduction to the special issue
Authors: Brown Stephen
Published: May 2004

Provides an introduction to the Special Issue by discussing the nature of marketing science in a postmodern world. Argues that science needs marketing more than marketing needs science. (Look folks, I didn’t want to include a review of my own book, but the regular journal editor insisted ‐ honest! ‐ and, anyway, Thompson was desperate for the publication. I’m just too soft, that’s my problem. Please excuse my unacademic behaviour. Pretty please.)
Modelling expert resource management systems
Authors: Kutti Swamy , Garner Brian , Ghosal Amitava
Published: May 2004

The data structuring mechanisms provided by the current problem solving environment have been found to satisfy modeling the problem solutions for common decision making processes of a static nature, whereas problems of a complex nature (e.g. resource management and optimization) need an abstract data structuring mechanism capable of emulating real‐life objects (e.g. human managers). This paper explains the concept of developing a new data structure based on a semantic network called SYSTEM MAP and shows how this novel data structure can be used to model expert resource management systems of a particularly hierarchical type.
Elements for a theory of fractals in dynamic systems involving human factors
Authors: Jumarie Guy
Published: May 2004

The theory which is addressed in this paper is that we should not be surprised to come across fractals in the analysis of some dynamic systems involving human factors. Moreover, in substance, fractals in human behaviour is acceptable. For the convenience of the reader a primary background to some models of fractional Brownian motions which can be found in the literature is given, and then the main features of the complex‐valued model, via a random walk in the complex plane, recently introduced by the author are recalled. The practical meaning of the model is exhibited. The parallel of the central limit theorem here is Levy’s stability. If it is supposed that human decision‐makers work via an observation process which combines the Heisenberg principle and a quantization principle in the measurement, then fractal dynamics appears to be quite in order. The relation with the theory of relative information is exhibited. The conjecture is then the following: could this model explain why fractals appear in finance, for instance?
New results of convergence of Adomian’s method
Authors: Himoun N. , Abbaoui K. , Cherruault Y.
Published: May 2004

New results about convergence of Adomian’s method are presented. This method was developed by G. Adomian for solving non‐linear functional equations of different kinds. New conditions for obtaining convergence of the decomposition series are given. In a similar way, the convergence of a regularisation method which can, for example, be applied to Fredholm integral equations of the first kind, is proved.
Control of the first‐line human defence system An autocatalytic model
Authors: Kochel Bonawentura
Published: May 2004

A control of the first‐line human defence system, using mechanisms analogous to specific and non‐specific (parametric) triggering of phagocytosis, is proposed on the basis of an autocatalytic model of biphasic modulation of phagocyte luminescence by experimental peptide medicines. Properties of the autocatalytic model are described and its catastrophe and bifurcation sets determined. The mechanism analogous to parametric triggering is shown to result from a fold catastrophe produced by the changes in the autocatalytic interaction parameter characterising a given peptide preparation. Usefulness of the model was shown by its application to two distinct peptide preparations having different immunomodulatory properties.
Competing transformation models
Authors: Östermark Ralf , Aaltonen Jaana
Published: May 2004

The paper is presented in two parts. The first is concerned with the methodology of the competing transformation models and the second details the results of the empirical tests. In particular, it concentrates on empirical testing of the stability and cross‐sectional invariance of the factor patterns underlying the arbitrage pricing models of two neighbouring security markets. In previous studies, the method of transformation analysis has been used to address these issues at the individual asset level. In the present study three alternative transformation analysis models are used to study the stability and invariance problems. The tests are carried out at an aggregated level, such that subsets of asset returns are combined in equally weighted portfolios in the spirit of Fama and MacBeth. Portfolio formation is motivated by the observed anomalies of individual asset return series. Even if some anomalies may be present on the aggregated level also, their impact will be weaker. The amount of different issues of the same company in the database is varied in order to study the impact of parallel issues on the empirical results.
Web search engine advertising practices and their effect on library service
Authors: Moxley David , Blake Joni , Maze Susan
Published: May 2004

Librarians have traditionally helped users meet their information needs by providing access to vetted sources. This changed when Internet access to the Web was introduced into the library service equation. While users now have access to more information than ever before, they must rely on search engines to retrieve and rank the results of their searches before research can begin. A problem with ranked retrieval is that many search engines participate in the practice of pay‐for‐placement advertising, which can affect the order of ranking, and may not be apparent as advertising. This practice introduces a new variation in the relationship between user and advertiser that has not existed in libraries before.
Reconceptualizing a dynamic model of organizational learning for schools
Authors: Jack Lam Y.L.
Published: May 2004

As a follow‐up to an earlier effort to distinguish schools by stages of development along the context of organizational learning (OL), this paper further targets the OL processes and outcomes to generate a more dynamic and functional framework for sustaining and refining the earlier version of the typology. It is hoped that through such a framework, the conditions that register the developmental characteristics of a school organization can be readily pinpointed. By comparison of schools in different conditions, factors that promote or retard school progress towards attaining the status of a learning organization can also be extracted for organizational restructuring.
SIEM measurements of ultimate tensile strength and tensile modulus of jetted, UV‐cured epoxy resin microsamples
Authors: Chang Sheng , Attinger Daniel , Chiang Fu‐Pen , Zhao Yong , Patel Ranjana C.
Published: May 2004

Resin jetting with piezo print‐heads is in increasing use, and in the rapid prototyping industry, the merging quality between adjacent droplets will determine the mechanical properties and reliability of the products. Therefore, it is essential to find an experimental technique to ensure seamless inter‐droplet merging. Speckle interferometry with electron microscopy (SIEM) is a micro‐mechanics measurement technique that has a spatial resolution approaching a few nanometers. In this paper, SIEM is successfully applied to measure the ultimate tensile stress and tensile modulus of jetted, UV‐cured cationic resin microsamples. Results show that the microsamples exhibit similar properties to the bulk material properties and that jetting two layers on top of each other is not detrimental to the material properties.
Implementing a Web enabled performance measurement system
Authors: Turner Trevor , Creighton Stephen , Nudurupati Sai , Bititci Umit
Published: May 2004

This article describes how a Web‐enabled‐performance‐measurement system was designed, implemented and used to improve the business performance of a company processing aluminum foil in central Scotland. The benefits of the system are analyzed in the context of the business‐process‐based structure of the performance measurement system and the evolution of a business improvement culture led by an enlightened general manager. The importance of the use of statistical quality control techniques by the management team to monitor impact of critical input variables on process performance is emphasized.
Siemens’ business excellence model and sustainable development
Authors: Zhao Fang
Published: May 2004

This study shows that Siemens has assiduously endeavored to achieve business excellence and enhance the company’s economic value, and has made considerable efforts to address the issue of sustainable development in various ways. However, the study has also found that much is said than done and there are implementation issues and problems that deserve managers’ full attention. A series of recommendations are proposed to broadly address these issues and problems. Managers who have already embarked on, or intend to take, sustainability initiatives will find the study informative and insightful.
Efficiency of Estimating Vaccine Efficacy for Susceptibility and Infectiousness: Randomization by Individual Versus Household
Authors: Datta Susmita , Halloran M. Elizabeth , Longini Ira M.
Published: May 2004

Summary. In designing vaccine efficacy studies based on the secondary attack rate (SAR) or transmission probability in which both vaccine efficacy for susceptibility, VES, and vaccine efficacy for infectiousness, VEI, are estimated, the allocation of vaccine and placebo within transmission units has an important influence on the efficiency of the study. We compared the following randomization schemes that result in different allocations of vaccine and placebo within two‐member households: (1) randomization by individual for a mixed allocation, (2) randomization by transmission unit for concordant allocation, and (3) randomization of only one individual in each transmission unit to either vaccine or placebo. There is a complex interaction among the VES, VEI, and the SAR that determines which allocation of vaccine and placebo within households provides the most information. In general, individual randomization with a mixed allocation of vaccine and placebo is better for estimating both VES and VEI than is randomizing by household. However, for estimation of VEI, at very low SARs and low VES, randomization by household is slightly more efficient than randomization by individual.
Highly Resistant Regression and Object Matching
Authors: Dryden Ian L. , Walker Gary
Published: May 2004

Summary. In many disciplines, it is of great importance to match objects. Procrustes analysis is a popular method for comparing labeled point configurations based on a least squares criterion. We consider alternative procedures that are highly resistant t o outlier points, and we describe an application in electrophoretic gel matching. We consider procedures based on S estimators, least median of squares, and least quartile difference estimators. Practical implementation issues are discussed, including random subset selection and intelligent subset selection (where subsets with small size or near collinear subsets are ignored). The relative performances of the resistant and Procrustes methods are examined in a simulation study.
Fitting the log‐FAccelerated Failure Time Model with Incomplete Covariate Data
Authors: Cho Meehyung , Schenker Nathaniel
Published: May 2004

Summary.Data obtained from studies in the health sciences often have incompletely observed covariates as well as censored outcomes. In this paper, we present methods for fitting the log‐Faccelerated failure time model with incomplete continuous and/or categorical time‐independent covariates using the Gibbs sampler. A general location model that allows different covariance structures across cells is specified for the covariates, and ignorable missingness of the covariates is assumed. Techniques that accommodate standard assumptions of ignorable censoring as well as certain types of nonignorable censoring are developed. We compare our approach to traditional complete‐case analysis in an application to data obtained from a study of melanoma. The comparison indicates that substantial gains in efficiency are possible with our approach.
Regression Analysis of Doubly Censored Failure Time Data with Applications to AIDS Studies
Authors: Sun Jianguo , Liao Qiming , Pagano Marcello
Published: May 2004

Summary.In many epidemiological studies, the survival time of interest is the elapsed time between two related events, the originating event and the failure event, and the times of the occurrences of both events are right or interval censored. We discuss the regression analysis of such studies and a simple estimating equation approach is proposed under the proportional hazards model. The method can easily be implemented and does not involve any iteration among unknown parameters, as full likelihood approaches proposed in the literature do. The asymptotic properties of the proposed regression coefficient estimates are derived and an AIDS cohort study is analyzed to illustrate the proposed approach.
Relating the Classical Covariance Adjustment Techniques of Multivariate Growth Curve Models to Modern Univariate Mixed Effects Models
Authors: Mikulich Susan K. , Zerbe Gary O. , Jones Richard H. , Crowley Thomas J.
Published: May 2004

Summary. The relationship between the modern univariate mixed model for analyzing longitudinal data, popularized by Laird and Ware (1982, Biometrics38, 963–974), and its predecessor, the classical multivariate growth curve model, summarized by Grizzle and Allen (1969, Biometrics25, 357–381), has never been clearly established. Here, the link between the two methodologies is derived, and balanced polynomial and cosinor examples cited in the literature are analyzed with both approaches. Relating the two models demonstrates that classical covariance adjustment for higher‐order terms is analogous to including them as random effects in the mixed model. The polynomial example clearly illustrates the relationship between the methodologies and shows their equivalence when all matrices are properly defined. The cosinor example demonstrates how results from each method may differ when the total variance‐covariance matrix is positive definite, but that the between‐subjects component of that matrix is not so constrained by the growth curve approach. Additionally, advocates of each approach tend to consider different covariance structures. Modern mixed model analysts consider only those terms in a model's expectation (or linear combinations), and preferably the most parsimonious subset, as candidates for random effects. Classical growth curve analysts automatically consider all terms in a model's expectation as random effects and then investigate whether “covariance adjusting” for higher‐order terms improves the model. We apply mixed model techniques to cosinor analyses of a large, unbalanced data set to demonstrate the relevance of classical covariance structures that were previously conceived for use only with completely balanced data.
Likelihood‐Based Experimental Design for Estimation of Ed 50
Authors: Minkin Salomon , Kundhal Kiran
Published: May 2004

Summary.In selecting the best dosage choice for the estimation of ED 50, it is natural to try to minimize the length of the confidence intervals. In this presentation, the dose allocation that minimizes the length of the likelihood‐based confidence intervals is presented and compared with alternative allocations that have been proposed based on the length of different types of confidence intervals, such as those based on the asymptotic variance or on Fieller's Theorem. Effective strategies to deal with the parameter dependence of these allocations are explored. A series of experiments to evaluate the effect of small doses per fraction on the radiation tolerance of the rat cervical spinal cord provide the motivation and an illustration for the proposed procedures.
Bayesian Survival Analysis Using A Mars Model
Authors: Mallick Bani K. , Denison David G. T. , Smith Adrian F. M.
Published: May 2004

Summary.A Bayesian multivariate adaptive regression spline fitting approach is used to model univariate and multivariate survival data with censoring. The possible models contain the proportional hazards model as a subclass and automatically detect departures from this. A reversible jump Markov chain Monte Carlo algorithm is described to obtain the estimate of the hazard function as well as the survival curve.
Sequential Methods for Comparing Years of Life Saved in the Two‐Sample Censored Data Problem
Authors: Murray Susan , Tsiatis Anastasios A.
Published: May 2004

Summary. This research develops nonparametric strategies for sequentially monitoring clinical trial data where detecting years of life saved is of interest. The recommended test statistic looks at integrated differences in survival estimates during the time frame of interest. In many practical situations, the test statistic presented has an independent increments covariance structure. Hence, with little additional work, we may apply these testing procedures using available methodology. In the case where an independent increments covariance structure is present, we suggest how clinical trial data might be monitored using these statistics in an information‐based design. The resulting study design maintains the desired stochastic operating characteristics regardless of the shapes of the survival curves being compared. This offers an advantage over the popular log‐rank‐based design strategy since more restrictive assumptions relating to the behavior of the hazards are required to guarantee the planned power of the test. Recommendations for how to sequentially monitor clinical trial progress in the non‐independent increments case are also provided along with an example.
The Two‐Sample Problem with Induced Dependent Censorship
Authors: Huang Yijian
Published: May 2004

Summary.Induced dependent censorship is a general phenomenon in health service evaluation studies in which a measure such as quality‐adjusted survival time or lifetime medical cost is of interest. We investigate the two‐sample problem and propose two classes of nonparametric tests. Based on consistent estimation of the survival function for each sample, the two classes of test statistics examine the cumulative weighted difference in hazard functions and in survival functions. We derive a unified asymptotic null distribution theory and inference procedure. The tests are applied to trial V of the International Breast Cancer Study Group and show that long duration chemotherapy significantly improves time without symptoms of disease and toxicity of treatment as compared with the short duration treatment. Simulation studies demonstrate that the proposed tests, with a wide range of weight choices, perform well under moderate sample sizes.
Normal Approximation Diagnostics for the Cox Model
Authors: Chang Chung‐Chou H. , Weissfeld Lisa A.
Published: May 2004

Summary.We discuss two diagnostic methods for assessing the accuracy of the normal approximated confidence region to the likelihood‐based confidence region for the Cox proportional hazards model with censored data. The proposed diagnostic methods are extensions of the contour measures of Hodges (1987,Journal of the American Statistical Association82, 149–154) and Cook and Tsai (1990,Journal of the American Statistical Association85, 770–777) and the curvature measures of Jennings (1986,Journal of the American Statistical Association81, 471–476) and Cook and Tsai (1990). These methods are also illustrated in a study of hepatocyte growth factor in patients with lung cancer and a Mayo Clinic randomized study of participants with primary biliary cirrhosis.
Hierarchical Proportional Hazards Regression Models for Highly Stratified Data
Authors: Carlin Bradley P. , Hodges James S.
Published: May 2004

Summary.In clinical trials conducted over several data collection centers, the most common statistically defensible analytic method, a stratified Cox model analysis, suffers from two important defects. First, identification of units that are outlying with respect to the baseline hazard is awkward since this hazard is implicit (rather than explicit) in the Cox partial likelihood. Second (and more seriously), identification of modest treatment effects is often difficult since the model fails to acknowledge any similarity across the strata. We consider a number of hierarchical modeling approaches that preserve the integrity of the stratified design while offering a middle ground between traditional stratified and unstratified analyses. We investigate both fully parametric (Weibull) and semiparametric models, the latter based not on the Cox model but on an extension of an idea by Gelfand and Mallick (1995,Biometrics51, 843–852), which models the integrated baseline hazard as a mixture of monotone functions. We illustrate the methods using data from a recent multicenter AIDS clinical trial, comparing their ease of use, interpretation, and degree of robustness with respect to estimates of both the unit‐specific baseline hazards and the treatment effect.
Adaptive Sample Size Calculations in Group Sequential Trials
Authors: Lehmacher Walter , Wassmer Gernot
Published: May 2004

Summary.A method for group sequential trials that is based on the inverse normal method for combining the results of the separate stages is proposed. Without exaggerating the Type I error rate, this method enables data‐driven sample size reassessments during the course of the study. It uses the stopping boundaries of the classical group sequential tests. Furthermore, exact test procedures may be derived for a wide range of applications. The procedure is compared with the classical designs in terms of power and expected sample size.
Multiple Comparison of Entropies with Application to Dinosaur Biodiversity
Authors: Fritsch Kathleen S. , Hsu Jason C.
Published: May 2004

Summary. Did the biodiversity of dinosaurs decline, or did it remain more or less constant before their mass extinction 65 million years ago? Sheehan et al. (1991, Science, 835–839) reported that the biodiversity of families of dinosaur species remained more or less constant preceding their extinction, suggesting extinction due to a cataclysmic event such as an asteroid strike. But that claim was based on the incorrect interpretation that a large p value associated with a test of null hypothesis of equality supports that null hypothesis. To assess whether there is a basis for such a claim, we formulate the problem as one of practical equivalence, in analogy to bioequivalence. We then develop reliable practical equivalence confidence intervals for differences of entropies by applying the bootstrap‐t technique to a nearly pivotal quantity. Confidence intervals for changes in the biodiversity of dinosaurs are then computed, allowing the reader to assess whether there is evidence of near constancy of dinosaur biodiversity before extinction.
Bayesian Detection of Clusters and Discontinuities in Disease Maps
Authors: Knorr‐Held Leonhard , Raßer Günter
Published: May 2004

Summary. An interesting epidemiological problem is the analysis of geographical variation in rates of disease incidence or mortality. One goal of such an analysis is to detect clusters of elevated (or lowered) risk in order to identify unknown risk factors regarding the disease. We propose a nonparametric Bayesian approach for the detection of such clusters based on Green's (1995, Biometrika82, 711–732) reversible jump MCMC methodology. The prior model assumes that geographical regions can be combined in clusters with constant relative risk within a cluster. The number of clusters, the location of the clusters, and the risk within each cluster is unknown. This specification can be seen as a change‐point problem of variable dimension in irregular, discrete space. We illustrate our method through an analysis of oral cavity cancer mortality rates in Germany and compare the results with those obtained by the commonly used Bayesian disease mapping method of Besag, York, and Mollié (1991, Annals of the Institute of Statistical Mathematics, 43, 1–59).
Estimating Data Transformations in Nonlinear Mixed Effects Models
Authors: Oberg Ann , Davidian Marie
Published: May 2004

Summary.A routine practice in the analysis of repeated measurement data is to represent individual responses by a mixed effects model on some transformed scale. For example, for pharmacokinetic, growth, and other data, both the response and the regression model are typically transformed to achieve approximate within‐individual normality and constant variance on the new scale; however, the choice of transformation is often made subjectively or by default, with adoption of a standard choice such as the log. We propose a mixed effects framework based on the transform‐both‐sides model, where the transformation is represented by a monotone parametric function and is estimated from the data. For this model, we describe a practical fitting strategy based on approximation of the marginal likelihood. Inference is complicated by the fact that estimation of the transformation requires modification of the usual standard errors for estimators of fixed effects; however, we show that, under conditions relevant to common applications, this complication is asymptotically negligible, allowing straightforward implementation via standard software.
Conditional‐Cumulant‐of‐Exposure Method in Logistic Missing Covariate Regression
Authors: Wang C. Y. , Huang Wen‐Tao
Published: May 2004

Summary.We consider estimation in logistic regression where some covariate variables may be missing at random. Satten and Kupper (1993,Journal of the American Statistical Association88, 200–208) proposed estimating odds ratio parameters using methods based on the probability of exposure. By approximating a partial likelihood, we extend their idea and propose a method that estimates the cumulant‐generating function of the missing covariate given observed covariates and surrogates in the controls. Our proposed method first estimates some lower order cumulants of the conditional distribution of the unobserved data and then solves a resulting estimating equation for the logistic regression parameter. A simple version of the proposed method is to replace a missing covariate by the summation of its conditional mean and conditional variance given observed data in the controls. We note that one important property of the proposed method is that, when the validation is only on controls, a class of inverse selection probability weighted semiparametric estimators cannot be applied because selection probabilities on cases are zeros. The proposed estimator performs well unless the relative risk parameters are large, even though it is technically inconsistent. Small‐sample simulations are conducted. We illustrate the method by an example of real data analysis.
Variance and Sample Size Calculations in Quality‐of‐Life‐Adjusted Survival Analysis (Q‐TWiST)
Authors: Murray Susan , Cole Bernard
Published: May 2004

Summary. The Quality‐Adjusted Time Without Symptoms or Toxicity (Q‐TWiST) statistic previously introduced by Glasziou, Simes and Gelber (1990, Statistics in Medicine9, 1259–1276) combines toxicity, disease‐free survival, and overall survival information in assessing the impact of treatments on the lives of patients. This methodology has received positive reviews from clinicians as intuitive and useful, but to date, the variance of this statistic has remained unspecified. We review aspects of the Q‐TWiST method for analyzing clinical trial data, extend the method to accommodate multiple treatment arms, and provide closed‐form asymptotic variance formulas. We also provide a framework for designing Q‐TWiST clinical trials with sample sizes determined using the derived asymptotic variance formulas. Trials currently collecting quality of life data did not have the benefit of these sample size calculation techniques in designing their studies.
A Nonparametric Mixture Model for Cure Rate Estimation
Authors: Peng Yingwei , Dear Keith B. G.
Published: May 2004

Summary.Nonparametric methods have attracted less attention than their parametric counterparts for cure rate analysis. In this paper, we study a general nonparametric mixture model. The proportional hazards assumption is employed in modeling the effect of covariates on the failure time of patients who are not cured. The EM algorithm, the marginal likelihood approach, and multiple imputations are employed to estimate parameters of interest in the model. This model extends models and improves estimation methods proposed by other researchers. It also extends Cox's proportional hazards regression model by allowing a proportion of event‐free patients and investigating covariate effects on that proportion. The model and its estimation method are investigated by simulations. An application to breast cancer data, including comparisons with previous analyses using a parametric model and an existing nonparametric model by other researchers, confirms the conclusions from the parametric model but not those from the existing nonparametric model.
Alx4 and Msx2 play phenotypically similar and additive roles in skull vault differentiation
Authors: Antonopoulou Ileana , Mavrogiannis Lampros A. , Wilkie Andrew O. M. , Morriss‐Kay Gillian M.
Published: May 2004

Alx4 and Msx2 encode homeodomain‐containing transcription factors that show a clear functional overlap. In both mice and humans, loss of function of either gene is associated with ossification defects of the skull vault, although the major effect is on the frontal bones in mice and the parietal bones in humans. This study was undertaken to discover whether Alx4 and Msx2 show a genetic interaction in skull vault ossification, and to test the hypothesis that they interact with the pathway that includes the Fgfr genes, Twist1 and Runx2. We generated Alx4+/–/Msx2+/– double heterozygous mutant mice, interbred them to produce compound genotypes and analysed the genotype–phenotype relationships. Loss of an increasing number of alleles correlated with an incremental exacerbation of the skull vault defect; loss of Alx4 function had a marginally greater effect than loss of Msx2 and also affected skull thickness. In situ hybridization showed that Alx4 and Msx2 are expressed in the cranial skeletogenic mesenchyme and in the growing calvarial bones. Studies of the coronal suture region at embyonic day (E)16.5 revealed that Alx4 expression was decreased, but not abolished, in Msx2−/– mutants, and vice versa; expression of Fgfr2 and Fgfr1, but not Twist1, was reduced in both mutants at the same stage. Runx2 expression was unaffected in the coronal suture; in contrast, expression of the downstream ossification marker Spp1 was delayed. Double homozygous pups showed substantial reduction of alkaline phosphatase expression throughout the mineralized skull vault; they died at birth due to defects of the heart, lungs and diaphragm not previously associated with Alx4 or Msx2. Our observations suggest that Alx4 and Msx2 are partially functionally redundant, acting within a network of transcription factors and signalling events that regulate the rate of osteogenic proliferation and differentiation at a stage after the commitment of mesenchymal stem cells to osteogenesis.
Integrin expression in cells of the intervertebral disc
Authors: Nettles Dana L. , Richardson William J. , Setton Lori A.
Published: May 2004

In this study, we investigated the profile of integrin expression in human and porcine intervertebral disc tissue. Differences in extracellular matrix composition between anulus fibrosus (AF) and nucleus pulposus (NP) regions of the disc, as well as differences in cellular responses to environmental stimuli, suggest a role for integrins in presenting matrix signals that may mediate these responses. Human disc tissue and porcine AF and NP tissue were stained with antibodies to alpha integrin subunits 1–6, V and IIb, and beta integrin subunits 1–6 and graded for evidence of positive staining on a scale from 0 (no staining) to 3 (high incidence of staining). Human tissue expressed α and β integrin subunits shown to be present in articular cartilage, including α1, α5 and αV. Porcine AF tissue expressed similar integrin subunits to human disc, with both expressing α1, α5, β1, β3 and β5 subunits, whereas porcine NP tissue expressed higher levels of α6, β1 and β4 than AF tissue. The expressed subunits are known to interact with proteins including collagens, fibronectin and laminin; however, additional studies will be required to characterize the interactions of the integrin subunits with specific matrix constituents, as well as their specific involvement in regulating environmental stimuli.
The Desirable Organizational Structure for Evolutionary Firms in Static Landscapes
Authors: Garrido Nicolás
Published: May 2004

In addition to the common analysis of the KauffmanNKmodel where the value ofKand the structure of interaction are given, the aim of this paper is to study what the values of these two parameters would be if they were endogenized. Thus, a model is proposed where firms and business schools coordinate to search for high peaks in their respective landscapes using evolutionary algorithms. The main result coming from the analysis of the model is that agents, using evolutionary algorithms, attempt to simplify the problems of coordination and this, over time, produces the existence in the economy of agents using many different strategies.
Contrasting movement patterns in two species of chequerspot butterflies,Euphydryas auriniaandMelitaea phoebe, in the same patch network
Authors: Wang Rongjiang , Wang Yifei , Chen Jiejun , Lei Guangchun , Xu Rumei
Published: May 2004

Abstract. 1. Mark–release–recapture studies were conducted on two species of chequerspot butterfly,Euphydryas auriniaandMelitaea phoebe, in the same habitat patch network in Yanjiaping, a small basin in the Taihang Mountains, north‐west of Beijing, China, in 2000.

2.Euphydryas auriniatended to stay in the habitat patches and to move to neighbouring patches, whereasM. phoebemoved widely among patches in the entire network.

3. The parameters of the virtual migration model showed higher daily emigration propensity inM. phoebeand inE. auriniamales than inE. auriniafemales, and significantly greater average daily movement distance inM. phoebethan inE. aurinia.

4. The results are consistent with the previous findings showing genetic structuring among local populations ofE. auriniabut not among local populations ofM. phoebe.

5. Based on the genetic and ecological results, it was concluded thatE. auriniahas a classic metapopulation in the study area, whereasM. phoebeappears to have a source–sink metapopulation.

6. In 2000, when there was an overall increase in the abundance of the two species, the limited mobility ofE. auriniaresulted in an increase in the average local population size, whereas the increase in the number of local populations inM. phoebewas due to its high mobility.
Optimal Dynamic Trading Strategies
Authors: Breeden Douglas T.
Published: May 2004

This article presents a straightforward technique for computing solutions to discrete, multi‐period consumption/investment problems. It solves for the optimal stochastic consumption plans, as well as the optimal dynamic trading strategies that maximize utility for an individual. The technique permits general utility functions that may or may not be time‐separable. It also allows general changes in the investment opportunity set and allows the user to impose upper and lower bounds on trading behaviour. Divergent borrowing and lending rates can be handled, as can stochastic labour income risks. Computed solutions verify the predictions of well‐known intertemporal works by Merton, Breeden and others.

J.E.L.:G13).
Top‐down and bottom‐up regulation of herbivores: Spodoptera frugiperda turns tables on endophyte‐mediated plant defence and virulence of an entomopathogenic nematode
Authors: Richmond Douglas S. , Kunkel Brian A. , Somasekhar Nethi , Grewal Parwinder S.
Published: May 2004

Abstract.  1. The fungus Neotyphodium lolii forms a symbiotic relationship with its grass host Lolium perenne (perennial ryegrass). The fungus benefits from access to plant nutrients and photosynthate, whereas the plant benefits from acquired chemical defence against herbivory.

2. This study examined the potential for endophyte‐mediated plant defences to influence interactions between fall armyworm Spodoptera frugiperda, and the entomopathogenic nematode Steinernema carpocapsae and clarified biological mechanisms underlying the observations made.

3. In laboratory and greenhouse experiments, S. frugiperda larvae were fed endophytic or non‐endophytic L. perenne then exposed to S. carpocapsae or injected with the nematodes' symbiotic bacteria Xenorhabdus nematophila.

4. In all instances, S. frugiperda larvae fed endophyte‐infected grass suffered significantly lower mortality than those fed non‐endophytic plants. Although larvae fed endophyte‐infected grass often had significantly lower biomass than those fed uninfected grass, these differences did not account for altered susceptibility to S. carpocapsae.

5. Endophyte‐mediated reductions in herbivore susceptibility to the nematode pathogen represent a herbivore adaptation that effectively turns the tables on both plant and natural enemy by reducing the virulence of the nematodes' symbiotic bacteria while expanding the temporal window of herbivory.
Calcium measurement in living filamentous fungi expressing codon‐optimized aequorin
Authors: Nelson G. , Kozlova‐Zwinderman O. , Collis A. J. , Knight M. R. , Fincham J. R. S. , Stanger C. P. , Renwick A. , Hessing J. G. M. , Punt P. J. , Van Den Hondel C. A. M. J. J. , Read N. D.
Published: May 2004

Calcium signalling is little understood in filamentous fungi largely because easy and routine methods for calcium measurement in living hyphae have previously been unavailable. We have developed the recombinant aequorin method for this purpose. High levels of aequorin expression were obtained in Neurospora crassa, Aspergillus niger and Aspergillus awamori by codon optimization of the aequorin gene. Three external stimuli (mechanical perturbation, hypo‐osmotic shock and high external calcium) were found transiently to increase [Ca2+]c. Each of the calcium signatures associated with these physico‐chemical treatments was unique, suggesting the involvement of three distinct calcium‐mediated signal transduction pathways. The fungal calcium channel blocker KP4 inhibited the [Ca2+]c responses to hypo‐osmotic shock and high external calcium, but not to mechanical perturbation. The divalent cation chelator BAPTA inhibited [Ca2+]c responses to mechanical perturbation and hypo‐osmotic shock. The calcium agonists A23187 and cyclopiazonic acid increased [Ca2+]c levels.
The RING‐finger domain of the fungal repressor crgA is essential for accurate light regulation of carotenogenesis
Authors: Lorca‐Pascual Juan M. , Murcia‐Flores Laura , Garre Victoriano , Torres‐Martínez Santiago , Ruiz‐Vázquez Rosa M.
Published: May 2004

Mucor circinelloides responds to blue light by activating the biosynthesis of carotenoids. Gene crgA acts as a repressor of this light‐regulated process, as its inactivation leads to overaccumulation of carotenoids in both the dark and the light. The predicted CrgA protein contains different recognizable structural domains, including a RING‐finger zinc‐binding motif, several glutamine‐rich regions, a putative nuclear localization signal and an isoprenylation domain. To gain insight into the specific mode of action of the CrgA protein, we sought to define the CrgA domains critical for the light regulation of carotenogenesis. For this, mutant crgA alleles harbouring missense or deletion mutations in conserved residues of those domains were generated, and their functionality was assessed by testing their ability to complement a null crgA mutation. Point mutations of the amino‐terminal RING‐finger domain abrogated the ability of CrgA to repress carotenogenesis in the dark, as did the deletion of a poly glutamine‐rich region at the carboxyl domain of CrgA. In contrast, mutations of the isoprenylation domain only slightly affected the CrgA function in carotenogenesis. The results identify two functional domains presumably involved in protein–protein interaction in the CrgA protein and suggest a role for the ubiquitin–proteasome pathway in the light regulation of carotenogenesis in fungi.
The FNR‐type transcriptional regulator SinR controls maturation of Agrobacterium tumefaciens biofilms
Authors: Ramey Bronwyn E. , Matthysse Ann G. , Fuqua Clay
Published: May 2004

Agrobacterium tumefaciens is a plant pathogen that persists as surface‐associated populations on plants or soil particles. A genetic screen for A. tumefaciens mutants deficient for surface interactions identified a mutant that forms thin, sparsely populated biofilms, but is proficient for initial attachment. The mutant is disrupted in a gene designated sinR, encoding a member of the DNR subfamily of FNR‐type transcription regulators. SinR is required for normal maturation of A. tumefaciens biofilms on both inert surfaces and plant tissues, and elevated sinR expression results in accelerated biofilm formation. Expression of sinR is increased close to 30‐fold in cultures grown in oxygen‐limited environments and is also induced within biofilms grown under oxic conditions. A consensus FNR box, the presumptive binding site for FNR‐type proteins, is located upstream of the sinR promoter. FnrN, a second A. tumefaciens FNR‐like regulator, is required for induction of sinR in oxygen‐limited cultures, whereas SinR negatively influences its own expression. FnrN influences biofilm formation, but its effects are less dramatic than those of SinR. We propose a model in which a signal cascade, responsive to oxygen limitation and initiated by FnrN, activates sinR expression in response to decreased oxygen levels, and influences the formation of A. tumefaciens biofilms.
Upper Carboniferous to Lower Permian volcanic successions of the Carroll–Nandewar region, northern Tamworth Belt, southern New England Orogen, Australia*
Authors: ROBERTS J. , OFFLER R. , FANNING M.
Published: May 2004

Geological mapping in the Carroll–Nandewar region near the northwestern margin of the Tamworth Belt has identified an Upper Carboniferous to Lower Permian succession, the Willuri Formation, containing coarse volcaniclastic sediments and interbedded dacitic to rhyolitic pyroclastics, lavas and a possible dome or coulée. The Currangandi Group (new) accommodates Upper Carboniferous volcaniclastic formations in the northern Tamworth Belt, including the Willuri Formation. Volcanic rocks in the Willuri Formation are distributed in four stratigraphically distinct, intertonguing or overlapping packages: the Kaputar, Piney Range, Tulcumba and Gunnan packages. According to SHRIMP (AS3) dating most of the succession ranges in age from ca 320 to ca 308 Ma (Namurian–Westphalian). Dacitic and rhyolitic lavas, apparently in sequence with the succession on the northwestern part of Tulcumba Ridge, are 297–287 Ma or younger (Early Permian). They appear to disconformably overlie the Carboniferous succession and could be either part of the Willuri Formation or related to the Boggabri Volcanics. Volcanic centres near Maules Creek (Kaputar centre) and Wean (Wean centre) appear to have been the sources for volcanics in the Kaputar package and most parts of the Rocky Creek region to the northeast, and the Tulcumba and probably the Piney Range packages, respectively. In the Gunnan package a single major ignimbrite was derived from a volcanic centre in the Werrie pyroclastic field, but the provenance of other pyroclastics is unknown. Correlations based on SHRIMP ages and the distribution of pyroclastics indicate that the Willuri Formation is equivalent to most of the Currabubula Formation in the Werrie Syncline, and to the Rocky Creek Conglomerate and Lark Hill Formation in the Rocky Creek region. Boundaries of the Werrie and Rocky Creek pyroclastic fields are adjusted to incorporate a new pyroclastic field based on the Wean volcanic centre and covering the Tulcumba and Piney Range packages of the Willuri Formation.
Cathodoluminescence study of carbonate cements in the Upper Cambrian conglomerates from the Wonominta Block, northwestern New South Wales
Authors: PAHL J. K. , SIKORSKA M.
Published: May 2004

Petrological studies were carried out on the Upper Cambrian conglomerates from the Bilpa and Cupala Creek areas, in the Wonominta Block, northwestern New South Wales. The sediments are post‐orogenic, molasse‐type, shaped in continental and shallow‐marine environments, and deposited in the form of major coarse‐grained deltas. Diagenetic processes caused an extensive lithification of these psephitic deposits. Multistage carbonate cementation is one of the most significant diagenetic changes that occurred. Several generations of carbonate cements have been distinguished based on observations under the polarising microscope, and particularly, using cathodoluminescence analysis. In both areas studied the conglomerates show four types of calcite cements under cathodoluminescence developed in the following order: non‐luminescent (+oscillatory zoned)–bright orange–dull orange–(non‐luminescent). The most likely sequence of carbonate cementation is presented involving eo‐, meso‐ and telo‐ stages of diagenesis. Minor malachite crystallised along with calcite in the telodiagenetic stage.