bluuebunny/crossref_metadata_2025 huggingface dataset:
A BayesianA‐Optimal and Model Robust Design Criterion
Authors: Zhou Xiaojie , Joseph Lawrence , Wolfson David B. , Bélisle Patrick
Published: December 2003

Summary. Suppose that the true model underlying a set of data is one of a finite set of candidate models, and that parameter estimation for this model is of primary interest. With this goal, optimal design must depend on a loss function across all possible models. A common method that accounts for model uncertainty is to average the loss over all models; this is the basis of what is known as Läuter's criterion. We generalize Läuter's criterion and show that it can be placed in a Bayesian decision theoretic framework, by extending the definition of BayesianA‐optimality. We use this generalizedA‐optimality to find optimal design points in an environmental safety setting. In estimating the smallest detectable trace limit in a water contamination problem, we obtain optimal designs that are quite different from those suggested by standardA‐optimality.
Incorporation of Clustering Effects for the Wilcoxon Rank Sum Test: A Large‐Sample Approach
Authors: Rosner Bernard , Glynn Robert J. , Ting Lee Mei‐Ling
Published: December 2003

Summary.  The Wilcoxon rank sum test is frequently used in statistical practice for the comparison of measures of location when the underlying distributions are far from normal or not known in advance. An assumption of the ordinary rank sum test is that individual sampling units are independent. In many ophthalmologic clinical trials, the Early Treatment for Diabetic Retinopathy Scale (ETDRS) is a principal endpoint used for measuring the level of diabetic retinopathy. This is an ordinal scale, and it is natural to consider the Wilcoxon rank sum test for the comparison of the level of diabetic retinopathy between treatment groups. However, under this design, unlike the usual Wilcoxon rank sum test, the subject is the unit of randomization, but the eye is the unit of analysis. Furthermore, a person will tend to have different, but correlated, ETDRS scores for fellow eyes. Thus, we propose a correction to the variance of the Wilcoxon rank sum statistic that accounts for clustering effects and that can be used for both balanced (same number of subunits per cluster) or unbalanced (different number of subunits per cluster) data, both in the presence or absence of ties, with p‐value adjusted accordingly. In this article, we present large‐sample theory and simulation results for this test procedure and apply it to diabetic retinopathy data from type I diabetics in the Sorbinil Retinopathy Trial.
The Gamma‐Frailty Poisson Model for the Nonparametric Estimation of Panel Count Data
Authors: Zhang Ying , Jamshidian Mortaza
Published: December 2003

Summary.  In this article, we study nonparametric estimation of the mean function of a counting process with panel observations. We introduce the gamma frailty variable to account for the intracorrelation between the panel counts of the counting process and construct a maximum pseudo‐likelihood estimate with the frailty variable. Three simulated examples are given to show that this estimation procedure, while preserving the robustness and simplicity of the computation, improves the efficiency of the nonparametric maximum pseudo‐likelihood estimate studied in Wellner and Zhang (2000, Annals of Statistics28, 779–814). A real example from a bladder tumor study is used to illustrate the method.
Issues of Cost and Efficiency in the Design of Reliability Studies
Authors: Shoukri M. M. , Asyali M. H. , Walter S. D.
Published: December 2003

Summary.  Reliability of continuous and dichotomous responses is usually assessed by means of the intraclass correlation coefficient (ICC). We derive the optimal allocation of the number of subjects k and the number of repeated measurements n that minimize the variance of the estimated ICC. Cost constraints are discussed for the case of normally distributed responses. Tables showing optimal choices of k and n are given, along with guidelines for the design of reliability studies in light of our results and those reported by others.
Graphical Exploration of Gene Expression Data: A Comparative Study of Three Multivariate Methods
Authors: Wouters Luc , Göhlmann Hinrich W. , Bijnens Luc , Kass Stefan U. , Molenberghs Geert , Lewi Paul J.
Published: December 2003

Summary.  This article describes three multivariate projection methods and compares them for their ability to identify clusters of biological samples and genes using real‐life data on gene expression levels of leukemia patients. It is shown that principal component analysis (PCA) has the disadvantage that the resulting principal factors are not very informative, while correspondence factor analysis (CFA) has difficulties interpreting distances between objects. Spectral map analysis (SMA) is introduced as an alternative approach to the analysis of microarray data. Weighted SMA outperforms PCA, and is at least as powerful as CFA, in finding clusters in the samples, as well as identifying genes related to these clusters. SMA addresses the problem of data analysis in microarray experiments in a more appropriate manner than CFA, and allows more flexible weighting to the genes and samples. Proper weighting is important, since it enables less reliable data to be down‐weighted and more reliable information to be emphasized.
Maximum Likelihood Methods for Nonignorable Missing Responses and Covariates in Random Effects Models
Authors: Stubbendick Amy L. , Ibrahim Joseph G.
Published: December 2003

Summary. This article analyzes quality of life (QOL) data from an Eastern Cooperative Oncology Group (ECOG) melanoma trial that compared treatment with ganglioside vaccination to treatment with high‐dose interferon. The analysis of this data set is challenging due to several difficulties, namely, nonignorable missing longitudinal responses and baseline covariates. Hence, we propose a selection model for estimating parameters in the normal random effects model with nonignorable missing responses and covariates. Parameters are estimated via maximum likelihood using the Gibbs sampler and a Monte Carlo expectation maximization (EM) algorithm. Standard errors are calculated using the bootstrap. The method allows for nonmonotone patterns of missing data in both the response variable and the covariates. We model the missing data mechanism and the missing covariate distribution via a sequence of one‐dimensional conditional distributions, allowing the missing covariates to be either categorical or continuous, as well as time‐varying. We apply the proposed approach to the ECOG quality‐of‐life data and conduct a small simulation study evaluating the performance of the maximum likelihood estimates. Our results indicate that a patient treated with the vaccine has a higher QOL score on average at a given time point than a patient treated with high‐dose interferon.
Exact Log‐Rank Tests for Unequal Follow‐Up
Authors: Heinze Georg , Gnant Michael , Schemper Michael
Published: December 2003

Summary. The asymptotic log‐rank and generalized Wilcoxon tests are the standard procedures for comparing samples of possibly censored survival times. For comparison of samples of very different sizes, an exact test is available that is based on a complete permutation of log‐rank or Wilcoxon scores. While the asymptotic tests do not keep their nominal sizes if sample sizes differ substantially, the exact complete permutation test requires equal follow‐up of the samples. Therefore, we have developed and present two new exact tests also suitable for unequal follow‐up. The first of these is an exact analogue of the asymptotic log‐rank test and conditions on observed risk sets, whereas the second approach permutes survival times while conditioning on the realized follow‐up in each group. In an empirical study, we compare the new procedures with the asymptotic log‐rank test, the exact complete permutation test, and an earlier proposed approach that equalizes the follow‐up distributions using artificial censoring. Results confirm highly satisfactory performance of the exact procedure conditioning on realized follow‐up, particularly in case of unequal follow‐up. The advantage of this test over other options of analysis is finally exemplified in the analysis of a breast cancer study.
Statistical Analysis of Noninferiority Trials with a Rate Ratio in Small‐Sample Matched‐Pair Designs
Authors: Chan Ivan S. F. , Tang Nian‐Sheng , Tang Man‐Lai , Chan Ping‐Shing
Published: December 2003

Summary.  Testing of noninferiority has become increasingly important in modern medicine as a means of comparing a new test procedure to a currently available test procedure. Asymptotic methods have recently been developed for analyzing noninferiority trials using rate ratios under the matched‐pair design. In small samples, however, the performance of these asymptotic methods may not be reliable, and they are not recommended. In this article, we investigate alternative methods that are desirable for assessing noninferiority trials, using the rate ratio measure under small‐sample matched‐pair designs. In particular, we propose an exact and an approximate exact unconditional test, along with the corresponding confidence intervals based on the score statistic. The exact unconditional method guarantees the type I error rate will not exceed the nominal level. It is recommended for when strict control of type I error (protection against any inflated risk of accepting inferior treatments) is required. However, the exact method tends to be overly conservative (thus, less powerful) and computationally demanding. Via empirical studies, we demonstrate that the approximate exact score method, which is computationally simple to implement, controls the type I error rate reasonably well and has high power for hypothesis testing. On balance, the approximate exact method offers a very good alternative for analyzing correlated binary data from matched‐pair designs with small sample sizes. We illustrate these methods using two real examples taken from a crossover study of soft lenses and a Pneumocystis carinii pneumonia study. We contrast the methods with a hypothetical example.
A Bivariate Frailty Model with a Cure Fraction for Modeling Familial Correlations in Diseases
Authors: Wienke Andreas , Lichtenstein Paul , Yashin Anatoli I.
Published: December 2003

Summary.  We suggest a cure‐mixture model to analyze bivariate time‐to‐event data, as motivated by the article of Chatterjee and Shih (2001, Biometrics57, 779–786), but with a simpler estimation procedure and the correlated gamma‐frailty model instead of the shared gamma‐frailty model. This approach allows us to deal with left‐truncated and right‐censored lifetime data, and accounts for heterogeneity, as well as for an insusceptible (cure) fraction in the study population. We perform a simulation study to evaluate the properties of the estimates in the proposed model and apply it to breast cancer incidence data for 5857 Swedish female monozygotic and dizygotic twin pairs from the so‐called old cohort of the Swedish Twin Registry. This model is used to estimate the size of the susceptible fraction and the correlation between the frailties of the twin partners. Possible extensions, advantages, and limitations of the proposed method are discussed.
Harnessing the Creative Potential among Users*
Authors: Kristensson Per , Gustafsson Anders , Archer Trevor
Published: December 2003

User involvement in the development of new products may offer a novel approach to improved methods of meeting customer needs. These users are considered to offer possibilities for generating original, valuable, and realizable ideas leading to successful innovation. However, the merit of users' ideas compared to ideas generated by the company itself has not been investigated empirically. In the present study, advanced users, ordinary users, and professional product developers were given the task of creating ideas for future mobile phone services. The main purpose was to examine the benefit of involving users in suggesting new product ideas in an innovation project. An experimental three‐group design was used in order to assess the output in terms of its original, valuable, and realizable merit. The results indicated that ordinary users create significantly more original and valuable ideas than professional developers and advanced users. Professional developers and advanced users created more easily realizable ideas, and ordinary users created the most valuable ideas. The results were discussed from the viewpoint of divergent thinking. It was suggested that divergent thinking was facilitated through the opportunity to combine different information elements that appeared separate at the outset, such as personal needs coupled with the functionality of mobile phone services.
FROM EXPERIENCE: Creating Synergy between Marketing and Research and Development*
Authors: Rein Gail L.
Published: December 2003

The tensions between marketing and research and development (R&D) are so common that we have come to accept them as the way organizations are. If we remain resigned like this, how will we ever reap some of the benefits that can accrue from these groups working better together? If we can improve the working relationships between marketing and R&D, researchers promise a variety of desirable organizational outcomes, such as cycle‐time reduction and new product success.

This article describes in detail the changes that a Fortune 500 company made to its product development process to foster synergy between marketing and R&D. The modified process formalized the roles of marketing and R&D at both the front and back ends of the product development process, increasing productive interaction between the groups. The company found that at the front end, marketing and R&D needed to work together (1) to clarify the market requirements implicit in the market attack plan and (2) to develop a technical strategy that responded to the market requirements and that consequently implemented the market attack plan. At the back end, the groups needed to work together (3) to formulate the value messages used to market the company's products. The synergy created between marketing and R&D through the new process is credited for enabling the company to compete successfully in a market it never before had entered.
Identity in Flexible Organizations: Experiences in Dutch Organizations
Authors: Schoemaker Michiel
Published: December 2003

In the information economy, flexible organizations have evolved. Work and labour relations have become more flexible than in industrial organizations. This has consequences for the identity of organizations. Organizations tend to become opportunity coalitions when the identity is too fragmented or neglected. The key questions this article adresses is what is identity in a flexible organization and to what extent is it possible to ‘manage’ the construction of identity in flexible organizations? This key question was split up into three sub‐questions. We were interested in how (1) organizations organize their talent management, (2) how organizations manage their labour relations and (3) how organizations manage identity. These three subjects come forward in recent publications in the field of organizational development and HRM as being critical of management of a flexible and innovative organization. In the article, the characteristics of flexible organizations are defined. These characteristics are translated into the relationship between these organization and individual: the way flexible organizations manage their work, labour relations and identity is studied in 20 Dutch organizations. Striving for an optimum in flexible work and flexible labour relations, combined with managing a specific organizational identity seems to be the HR‐strategy Dutch organizations implement to reach flexibility and innovation.
Chi and Organizational Creativity: A Case Study of Three Taiwanese Computer Firms
Authors: Hong Jon‐Chao , Hwang Ing‐Yueh , Lin Chan‐Li
Published: December 2003

The mechanisms of knowledge management include knowledge sharing, knowledge transformation and knowledge accumulation. In the corporate context, knowledge creation is of utmost importance for the promotion of competition within an organization. Knowledge creation in business corporations is most frequently done through sharing knowledge between members of a team. Therefore, how to promote the flow of ‘Chi’ in an organization to ensure the effectiveness of knowledge sharing becomes the key to successful knowledge creation. Moreover, to create and maintain ‘Chi’, a holonic working environment has to be created so that the result of knowledge sharing can be enhanced. This paper illustrates the effectiveness of the knowledge‐sharing practices of three computer‐manufacturing companies from the perspective of working environment design and knowledge‐sharing mechanism. Through comparison, this paper will identify some good practices for the enhancement of organizational creativity.
Engagement in Innovation Management: Perceptions and Interests in the GM Debate1
Authors: Weisenfeld Ursula
Published: December 2003

The development of a technology and the innovations based on that technology usually affect stakeholders who have different perceptions and interests. Key issues in the company's engagement with these stakeholders are information and negotiation. Engagement is an ongoing process during which perceptions as well as interests may change. In this article it is argued that knowing the nature of interests and perceptions of the involved parties at a certain critical point leads to possible ways of engagement which in turn may help creating a satisfying outcome of the innovation process. First, information is necessary to change perceptions, and second, negotiation is necessary to accommodate interests. Two examples from the biotechnology industries (genetically modified (GM) crops) are used to demonstrate that perceptions and interests are the key factors in driving the engagement process between a company and its stakeholders, and communication in the engagement process should emphasize giving information and/or negotiation, depending on the nature of perceptions and interests.
Innovation, Competitive Position and Industry Attractiveness: A Tool to Assist SMEs
Authors: Thacker Clive , Handscombe Bob
Published: December 2003

This paper reports the development of a tool to help SMEs identify more clearly their positions in their markets and to provide pointers to strategies that might lead to increased profitability. A nine‐cell matrix was constructed to form a new development based on the well‐established General Electric Co. (GE) matrix. It was proposed that companies could be positioned in one of the matrix cells as a function of two critical business indicators – competitive position and industry attractiveness. Data were gathered from a 21‐item innovation questionnaire completed by managing directors from 354 SMEs. Confirmatory factor analysis on data from the 21 items revealed two robust factors. The two factors could be labelled as the constructs ‘competitive position’ and ‘industry attractiveness’. These two constructs formed the axes of the matrix. Factor scores were calculated and used to place each company in its appropriate cell in the matrix. An individualised report was then generated and sent to each participating company. Positive feedback was received from companies who felt that the benchmarking and general pointers to strategic development included in their report provided value well in excess of their expectations.
How the Emotional Climate (Field) Impacts Performance
Authors: Prince George M.
Published: December 2003

Independently of the creativity movement, others have demonstrated the benefits of creating positive fields. I have reviewed a number of cases involving field below and added some from my own creativity experiences. I then explore the psychological explanation of why such fields are effective and go on to the findings of recent brain research, which not only reinforce the benefits of positive fields but also throw light on the difficulty of creating them. Finally, I offer some suggestions from my own experience of what can be done to create positive fields. I believe that this should now be the focus of our efforts: to the extent that we are successful, we should get the creativity and innovation we need as a by‐product.
Review
Authors: Barton Carol
Published: December 2003

Books reviewed in this article:

Andrew Lacey, Cult of King Charles the Martyr
Novel classical MHC class I alleles identified in horses by sequencing clones of reverse transcription‐PCR products
Authors: Chung C. , Leib S. R. , Fraser D. G. , Ellis S. A. , McGuire T. C.
Published: December 2003

Improved typing of horse classical MHC class I is required to more accurately define these molecules and to extend the number identified further than current serological assays. Defining classical MHC class I alleleic polymorphism is important in evaluating cytotoxic T lymphocyte (CTL) responses in horses. In this study, horse classical MHC class I genes were analyzed based on reverse transcription (RT)‐PCR amplification of sequences encoding the polymorphic peptide binding region and the more conserved alpha 3, transmembrane and cytoplasmic regions followed by cloning and sequencing. Primer sets included a horse classical MHC class I‐specific reverse primer and a forward primer conserved in all known horse MHC class I genes. Sequencing at least 25 clones containing MHC class I sequences from each of 13 horses identified 25 novel sequences and three others which had been described. Of these, nine alleles were identified from different horses or different RT‐PCR and 19 putative alleles were identified in multiple clones from the same RT‐PCR. The primer pairs did not amplify putative non‐classical MHC class I genes as only classical MHC class I and related pseudogenes were found in 462 clones. This method also identified classical MHC class I alleles shared between horses by descent, and defined differences in alleles between horses varying in equine leukocyte antigen (ELA)‐A haplotype as determined by serology. However, horses sharing ELA‐A haplotypes defined by serotyping did not always share cDNA sequences, suggesting subhaplotypic variations within serologically defined ELA‐A haplotypes. The 13 horses in this study had two to five classical MHC class I sequences, indicating that multiple loci code for these genes. Sequencing clones from RT‐PCR with classical MHC class I‐specific primers should be useful for selection of haplotype matched and mismatched horses for CTL studies, and provides sequence information needed to develop easier and more discriminating typing procedures.
Two novel somatic mutations in the human interleukin 6 promoter region in a patient with sporadic breast cancer
Authors: Saha A. , Bairwa N. K. , Ranjan A. , Gupta V. , Bamezai R.
Published: December 2003

Two new single nucleotide mutations were observed within the promoter region of human interleukin‐6 gene (IL‐6) in the tumour sample of a patient with sporadic breast cancer, which was a somatic change. Both mutations, one at −125 (C > G) and the other at position −173 (G > T) from the translation start site, were transversions observed at new positions, not reported earlier. In addition to these two novel mutations in this patient, a known somatic polymorphism was also observed at position −174 (G > C) (from the transcription initiation site, redesignated as −236 from the translational initiation site as per the HUGO nomenclature). Further, a preliminary comparative analysis of the studied promoter region by the ‘ConsInspector 3.0’ program, where the mutated sequence (AF362378) was compared with the sequence existing in the database (Y00081), depicted the presence of the variations in putative binding sites for transcription factors such as glucocorticoid response element (GRE) and nuclear factor kappa‐B (NFκ‐B), which could lead to differential expression of this gene.
Human platelet alloantigens (HPAs): PCR‐SSP genotyping of a UK population for 15 HPA alleles
Authors: Jones D. C. , Bunce M. , Fuggle S. V. , Young N. T. , Marshall S. E.
Published: December 2003

Alloimmunization to human platelet alloantigens (HPAs) is responsible for neonatal alloimmune thrombocytopenia (NAIT), post‐transfusional purpura (PTP) and platelet transfusion refractoriness. HPAs may also have a role as histocompatibility antigens in transplantation as well as associations with cardiac disease. We have developed a polymerase chain reaction–sequence‐specific primer (PCR‐SSP) assay capable of detecting 15 HPA allelic variants. As part of the validation of the assay, 134 UK renal donors were genotyped to determine HPA allele frequencies in the UK population. The HPA allele frequencies obtained are consistent with those of the other European studies: GP1A*1 (HPA‐5a) and GP1A*2 (HPA‐5b), 0.914 and 0.086, respectively; GP1BA*1 (HPA‐2a) and GP1BA*2 (HPA‐2b), 0.925 and 0.075; GP2B*1 (HPA‐3a) and GP2B*2 (HPA‐3b), 0.627 and 0.373; GP3A*1 (HPA‐1a) and GP3A*2 (HPA‐1b), 0.840 and 0.161. The rare alleles GP2B*3 (HPA‐9bw) and GP3A*3 to *8 (HPA‐4b, ‐6b, ‐7bw, ‐8bw, ‐10bw and ‐11bw, respectively) were all absent. This comprehensive HPA genotyping assay allows rapid, accurate and reproducible results at low cost.
IL12B and IRF1 gene polymorphisms and susceptibility to celiac disease
Authors: Seegers D. , Borm M. E. A. , Van Belzen M. J. , Mulder C. J. J. , Bailing J. , Crusius J. B. A. , Meijer J. W. R. , Wijmenga C. , Peña A. S. , Bouma G.
Published: December 2003

Celiac disease (CD) is a common gastro‐intestinal disorder resulting from permanent intolerance to wheat gliadins and related proteins in rye and barley. In addition to the strong genetic association with HLA‐DQ2 and HLA‐DQ8, a genetic region on chromosomes 5 (CELIAC2) has been identified that harbours a susceptibility gene for CD. The gene(s) responsible for this association, however, remains to be identified. In the present study we evaluated polymorphisms in the genes encoding interleukin‐12 p40 (IL12B) and interferon regulatory factor 1 (IRF1). Both genes are located in the celiac2 region, and have key roles in inducing interferon (IFN)‐γ secreting T helper 1 (Th1) cells, one of the immunological hallmarks of CD. The frequencies of a TaqI gene polymorphism in the 3′ UTR of IL12B and a HinfI gene polymorphism in the 3′ UTR of IRF1 were studied in 258 Dutch CD patients and 237 ethnically matched healthy controls. The transmission of the polymorphic variants from parents to affected child was determined in 123 families with at least one affected child. The frequencies of the IL12B TaqI gene polymorphism and the IRF1 HinfI gene polymorphism did not differ significantly between patients and controls. In addition, in the family study, no deviation from the expected transmission from parents to affected child of any of the polymorphic variants was found. The IL12B TaqI and the IRF1 HinfI gene polymorphisms do not appear to be involved in susceptibility to CD. Further studies on the factors that drive the Th1 immunopathology in CD are required.
Immunogenetics of a new HLA‐B null allele, HLA‐B*4423N
Authors: Hammond L. , Street J. , Downing J. , Thompson J. , Darke C.
Published: December 2003

The second example of an HLA‐B*44 null allele (B*4423N) was identified by discrepancies between serological and polymerase chain reaction–sequence‐specific primer (PCR‐SSP) typing in two north‐western European Caucasoid unrelated stem cell donor volunteers. HLA‐B*4423N was identical to B*440201 except for a single nucleotide substitution at position 493 in exon 3, resulting in a premature stop codon at bases 493–495 (TAG rather than CAG at codon 141). As expected, comprehensive serological testing using 54 antisera, directed towards B44 or Bw4, failed to identify the HLA‐B44 (Bw4) specificity. The B*4423N‐bearing haplotype was identified as A*0201, Cw*0501, DRB1*0408, DRB4*01, DQA1*03, DQB1*0304 and the frequency of B*4423N estimated as 0.00006 (carriage frequency 0.0121%) in 16 533 subjects resident in Wales.
Questing activity of Rhipicephalus appendiculatus (Acari: Ixodidae) nymphs: a random process?
Authors: Speybroeck N. , Madder M. , Brandt J. , Chungu H. , Van Den Bossche P. , Mbao V. , Berkvens D.
Published: December 2003

Abstract.  In Zambia, an experiment under quasi‐natural conditions indicated that Rhipicephalus appendiculatus nymphs react to prevailing climatic conditions. Higher temperatures and higher vapour pressure deficits lead to decreased activity. The majority of nymphs (>75%) were recorded at ground level. Simulations showed that larval phenology and temperature during the nymphal premoulting period largely explain the seasonal abundance patterns of nymphs, as observed on cattle, given the absence of a behavioural diapause. Consequently, the effect of climate, as observed in our studies, is masked. However, the results of the present study indicate that daily climatic conditions probably have a much larger effect on the transmission dynamics of Theileria parva. The vertical distribution of questing instars is a function of temperature and humidity. In years of unfavourable conditions, nymphs might feed mainly on hosts other than cattle, and this could govern the infection prevalence in the adult population. This suggestion is supported by previous epidemiological studies.
Fragrances, male display and mating behaviour of Euglossa hemichlora: a flight cage experiment
Authors: Eltz Thomas , Roubik David W. , Whitten Mark W.
Published: December 2003

Abstract.  Male euglossine bees (Apidae: Euglossini) collect volatile substances (fragrances) from floral and nonfloral sources and store them in hair‐filled cavities in their hind tibiae. Over time, males accumulate large quantities of complex and species‐specific blends of fragrances. Various hypotheses have been put forward to explain this behaviour, including the idea that fragrance stores reflect the genetic quality of individual males and have evolved through sexual selection and female choice. Clear support of this hypothesis is lacking, largely because male–female interactions are both rare and difficult to observe in nature. Here, we report a flight cage experiment performed in Panama that permitted mating between virgin females (raised from brood cells) and males captured in the forest at fragrance baits. In the cage, eight individually marked males defended small territories around vertical perch sites and showed a characteristic display, which included a previously unreported ‘leg‐crossing’ movement, possibly related to fragrance release. A total of six copulations and three copulatory attempts by Euglossa hemichlora were observed and partly recorded on video. The copulations, all of which were initiated by the female landing on a male perch, were short (4–10 s) and showed no signs of the transfer of chemical substances from male to female. In some cases, the male hovered directly over the female before descending to mount her, possibly facilitating fragrance evaluation by the female. After the experiment, the contents of the males' hind legs were analysed by gas chromatography‐mass spectroscopy, which detected complex mixtures of terpenoids and aromatics (totalling 70 different compounds) dominated by hexahydrofarnesyl acetone, farnesene epoxide, ocimene and p‐dimethoxy benzene. Individual total amounts of fragrances were neither related to display activity or perch occupancy by given males, nor to the frequency of matings achieved. Display activity was the only positive correlate of mating frequency. Generally, individuals had uniformly large amounts of stored fragrances in comparison to a previous study of three other species of Panamanian Euglossa.
Effect of biotic and abiotic factors on reproductive parameters of the synovigenic endoparasitoid Venturia canescens
Authors: Eliopoulos Panagiotis A. , Harvey Jeff A. , Athanassiou Christos G. , Stathas George J.
Published: December 2003

Abstract.  The main effects and interactions of adult age, access to food and host deprivation, on the egg load of Venturia canescens (Gravenhorst) (Hymenoptera: Ichneumonidae), a larval parasitoid of Ephestia kuehniella (Lepidoptera: Pyralidae) and other pyralids, were studied in the laboratory. Intraspecific variation in the number of ovarioles was also studied. There was a positive and significant correlation between wasp size and both egg load and ovariole number, with the reproductive system of large wasps containing significantly more ovarioles and mature eggs than small wasps. Newly emerged adult wasps contained 27 ± 2.4 ovulated (mature) eggs in their lateral oviducts. Access to food and host deprivation were the only conditions under which egg load increased with parasitoid age. Wasps that had access to hosts immediately after emergence showed a significant decline in their egg complement, irrespective of food presence. Under conditions of both host and food deprivation, there was practically no alteration of egg load with parasitoid age. A three‐way analysis of variance revealed that egg load varies significantly with food or host access but not with parasitoid age. All interactions among the three factors were significant. It is confirmed that there is no egg resorption in V. canescens and that egg production stops in the absence of food.
A phylogenetic analysis of the adipokinetic neuropeptides of Ensifera
Authors: Gäde Gerd , Marco Heather G. , Desutter‐Grandcolas Laure
Published: December 2003

Abstract.  Adipokinetic neuropeptides, from the corpora cardiaca of various species of the suborder Ensifera, encompassing members of all superfamilies (except the Gryllacridoidea), were isolated by liquid chromatography, and identified structurally by comparison of retention times and mass spectrometry data with respect to information from known members of this peptide family. Ensiferan species always contain only one adipokinetic hormone (AKH) peptide, as assessed for a few species by monitoring typical AKH mass peaks from a crude corpora cardiaca extract. This AKH is an octapeptide, and is either Scg‐AKH‐II (pGlu‐Leu‐Asn‐Phe‐Ser‐Thr‐Gly‐Trp amide) which occurs in all Tettigoniidea (except Schizodactyloidea) and in Gryllotalpoidea, or Grb‐AKH (pGlu‐Val‐Asn‐Phe‐Ser‐Thr‐Gly‐Trp amide) which occurs in Grylloidea (except Gryllotalpoidea) and Schizodactyloidea. Using the structural information of these neuropeptides in conjunction with morpho‐anatomical characters, these data are interpreted in a phylogenetic framework. The lack of a decapeptide and the presence of the octapeptide Scg‐AKH‐II are ancestral in Ensifera. The ancestral Scg‐AKH‐II twice underwent an independent and convergent modification to Grb‐AKH.
Effects of temperature and [His7]‐corazonin on the body darkening in Locusta migratoria
Authors: Tanaka Seiji
Published: December 2003

Abstract.  [His7]‐corazonin is a neuropeptide that induces dark coloration in locusts. This study examined the effect of temperature on body colour in the migratory locust, Locusta migratoria. L. Injection of a low dose (1 pmol) of [His7]‐corazonin caused albino nymphs to develop dark coloration at 25–34 °C, but little darkening occurred at 38 and 42 °C. However, injection of a high dose (10 pmol) induced darkening even at these high temperatures. Transfer of nymphs injected with 1 pmol of [His7]‐corazonin from 30 to 42 °C, and vice versa, indicated that temperature influenced darkening at any time after injection. Measurements of the luminance of the pronotum were made using commercially available computer software to follow continuous changes in darkening of the body. The body colour of nymphs injected with [His7]‐corazonin was reddish‐brown at 25 °C, blackish at 30 and 34 °C, and greyish or whitish at 38 and 42 °C. High temperature also suppressed darkening in a normal (pigmented) strain. Most nymphs transferred from 30 to 42 °C during the first three stadia developed a light colour in the fifth stadium without the striking black patterns that are typically manifested in gregarious nymphs at lower temperatures. Such individuals developed black patterns in the fifth stadium when injected with [His7]‐corazonin at a mid stage of the previous stadium. These results indicate that high temperature may induce light body coloration by suppressing the release of [His7]‐corazonin in normal locusts.
Host suitability, respiration rate and the outcome of larval competition in strains of the cowpea weevil, Callosobruchus maculatus
Authors: Guedes Raul Narciso C. , Smith Robert H. , Guedes Nelsa Maria P.
Published: December 2003

Abstract.  Variation between strains of Callosobruchus maculatus in several life‐history traits is well known. Differences in functional anatomy of egg pores and larval respiration rates have also been reported in strains from Brazil and Yemen. The response of five strains of C. maculatus to seeds of two host species, cowpea (Vigna unguiculata) and mung bean (Vigna radiata), was measured along with the larval respiration rates of the same strains on both hosts. There was significant variability of response to the two hosts. Strains with higher larval respiration rate (µL O2/insect/day) showed higher seed consumption, which significantly affected adult emergence per seed on both hosts. This finding provides support for the hypothesis that differential feeding rate is an important mechanistic component of the larval competition outcome observed in strains of C. maculatus.
Kairomonal effect of walking traces from Euschistus heros (Heteroptera: Pentatomidae) on two strains of Telenomus podisi (Hymenoptera: Scelionidae)
Authors: Borges Miguel , Colazza Stefano , Ramirez‐Lucas Pamela , Chauhan Kamlesh R. , Moraes Maria Carolina Blassioli , Richard Aldrich Jeffrey
Published: December 2003

Abstract.  The semiochemical cues used by geographically isolated strains of the parasitoid, Telenomus podisi (Ashmed), to find eggs of the stink bug Euschistus heros were investigated. Two strains of Te. podisi, maintained on eggs of a South American host (E. heros) were studied. One parasitoid strain originated from specimens collected near Brasilia, Brazil (SA strain), and a second strain originated from specimens collected at Beltsville, Maryland (NA strain). Cold tolerance tests of adults from the NA and SA Te. podisi strains, analyses of the cuticular hydrocarbons between the two strains, and crossing experiments between strains each indicated consistent differences between the NA and SA strains. Subsequent experiments using E. heros showed that SA Te. podisi females specifically recognize traces left on the substrate by walking E. heros females and then search intensively the area of the ‘footprints’, apparently looking for an egg mass to parasitize. By contrast, Te. podisi females of the NA strain are incapable of recognizing the footprints of E. heros females despite the fact that these parasitoids were reared from eggs of E. heros. The possibility that the two strains are actually different species is discussed.
Action spectra of phototactic responses of the flea beetle, Phyllotreta striolata
Authors: Yang En‐Cheng , Lee Der‐Wei , Wu Wen‐Yen
Published: December 2003

Abstract.  Adult flea beetles, Phyllotreta striolata, show a strong positive phototactic response. The action spectrum of phototaxis of dark‐adapted beetles was measured with minimal required light intensity between the wavelength range of 300 nm and 600 nm. Male and female flea beetles showed identical phototacitc behaviours. The beetles were most sensitive to light with peak wavelengths between 350 nm and 430 nm in the morning. In the afternoon and evening, the sensitivity to wavelengths shorter than 430 nm decreased, but they remained most sensitive to 430 nm. These results suggest that changes in sensitivity of the photoreceptors or nervous integration influence the phototactic responses, and that the blue wavelengths are more attractive than others.
Developmental thresholds and day‐degree requirements of Paratanytarsus grimmii and Corynoneura scutellata (Diptera: Chironomidae): two midges associated with potable water treatment
Authors: Olsen A. , Bale J. S. , Leadbeater B. S. C. , Callow M. E. , Holden J. B.
Published: December 2003

Abstract.  Studies on the development and mortality of Paratanytarsus grimmii (Schneider) and Corynoneura scutellata (Winnertz), which can infest potable water distribution networks, were carried out at eight constant temperatures between 10 °C and 27 °C. Using weighted linear regression, the developmental thresholds were calculated as 7.9 and 8.7 °C for P. grimmii and C. scutellata, respectively. Corynoneura scutellata had a day‐degree requirement of 172.4 per generation and developed significantly faster (P < 0.001) than P. grimmii with a day‐degree requirement of 294.1. Both species were identified as multivoltine with a maximum theoretical number of five generations per year for P. grimmii and seven for C. scutellata. These results are discussed in the context of the management of chironomid infestations within water‐treatment works.
Presence of three diapauses in a subtropical cockroach: control mechanisms and adaptive significance
Authors: Tanaka Seiji , Zhu Dao‐Hong
Published: December 2003

Abstract.  Diapause is common among insects and is regarded as an adaptive response to periodic occurrence of adverse conditions. It occurs at a particular developmental stage, typically only once in a lifetime. However, little is known about the details of the control mechanism of life cycles with multiple diapauses in insects. In this study, a complex 2‐year life cycle with three types of diapause is reported in a subtropical cockroach, Symploce japonica: a winter diapause in mid‐nymphal instars, a summer diapause in later nymphal instars, and a reproductive diapause is reported in the adult stage. Nymphal development was extremely slow either at short days (winter diapause) or long days (summer diapause). Nymphs in summer diapause matured rapidly when transferred from long days to short days, indicating that seasonal changes in day‐length are the pivotal factor in the control of this life cycle. It is proposed that the main significance of winter diapause in this subtropical species is to enable the nymphs to survive the mild winter successfully with reduced energy demand, and that of summer diapause is to delay adult emergence until late in the autumn for successful induction of the following adult diapause. Adults do not emerge until shortly before winter, yet the presence of diapause in the adult stage does not simply appear to be a response to cope with the winter conditions but, instead, ensures that reproduction will occur early the next year, before summer, because reproduction is greatly hampered at high temperature.
Constant rate allocation in nymphal development in species of Hemiptera
Authors: Perdikis Dionyssios CH. , Fantinou Argyro A. , Lykouressis Dionyssios P.
Published: December 2003

Abstract. This study investigated the existence of rate isomorphy (the constant allocation of relative times to different stages of development under different abiotic conditions) inMacrolophus pygmaeus(Hemiptera: Miridae; a phytophagous and predatory insect). Replicated data were used from a range of temperatures regarding (i) the developmental period of each nymphal stage in relation to the total duration of nymph development, when feeding on three host plants either with different prey species or without prey, and (ii) its egg, total nymphal and preoviposition period, on two host plants, with different prey species. The proportion of time required for the development of each nymphal stage ofM. pygmaeusis not different among the temperatures or the kind of food available. These proportions ranged among the different host plants, temperatures and prey presence/absence from 17.3–21.8% in the first, 14.5–18.8% in the second, 14.2–18.3% in the third, 16.5–21.0% in the fourth and from 25.4–30.6% in the fifth nymphal stage. Thus, temperature does not significantly affect the proportion of time spent in each nymphal stage and rate isomorphy exists in nymphal development. This phenomenon was also investigated using data from the literature, and it also occurs in several other Hemiptera species. Therefore, there appears to be a constant time allocation in the nymphal development of the higher taxonomic groups of insects. However, forM. pygmaeus, rate isomorphy does not hold when considering egg‐to‐egg development and the relative duration of times to egg hatch, total nymphal development and preoviposition period. The ecophysiological implications of this rate isomorphy phenomenon are discussed in relation to endocrinological mechanisms. Apart from its theoretical interest, the existence of rate isomorphy simplifies studies on the rate of development and the estimation of thermal constants of an insect, which are essential for the prediction of insect population dynamics. It is also proposed that the term ‘rate isomorphy’ does not strictly describe the phenomenon, and it is suggested that ‘constant rate allocation’ would be a more suitable term.
Exploitation of stem cell plasticity
Authors: Martin‐Rendon E. , Watt S. M.
Published: December 2003

Summary.  For many years, adult haemopoietic stem cells (HSCs) have been considered ‘plastic’ in their proliferative and differentiation capacities. Recently, evidence that supports newer concepts of adult stem cell plasticity has been reported. In particular, stem cells from haemopoietic tissues seem to have ‘extraordinary’ abilities to generate or switch between haemopoietic and nonhaemopoietic lineages, exhibiting an unexpected degree of developmental or differentiation potential. The mechanisms by which cell fate reprogramming occurs are still poorly understood. Nevertheless, an increasing number of studies is challenging one of the main dogmas in biology, namely that mammalian cell differentiation follows established programmes in a hierarchical fashion, and once committed to a particular somatic cell lineage, cells do not change into another somatic lineage. The ‘nonhierarchical’, ‘reversible’ phenotype of stem cells in haemopoietic tissues, if it exists, would be an advantage that could be exploited in regenerative medicine. Here, we review the recent advances in HSC biology and discuss the general concepts of adult stem cell plasticity with respect to these cells and how these might be exploited clinically.
Stem cells for the treatment of neurological disease
Authors: Rice C. M. , Halfpenny C. A. , Scolding N. J.
Published: December 2003

Summary.  Stem cells are widely believed to have significant potential in the treatment of human disease. Comments such as ‘[stem cells]…could prove the Holy Grail in finding treatments for cancer, Parkinson's disease, diabetes, osteoporosis, spinal cord injuries, Alzheimer's disease, leukaemia and multiple sclerosis… transform[ing] the lives of hundreds of thousands of people' (Yvette Cooper, Public Health minister, quoted in The Times, December 16 2000, authors' italics) serve to reinforce the extraordinary expectations of stem cells, particularly in neurological disease. Stem cells, traditionally defined as clone forming, self‐renewing, pluripotent, progenitor cells, have already proved themselves to be an invaluable source of transplantation material in several clinical settings, most notably malignant haematology, and attention is now turning to a wider variety of diseases in which there may be potential for therapeutic intervention with stem cell transplantation. Neurological diseases have been highlighted as a priority and this is understandable given their unenviable reputation for relentless progression and the paucity of disease‐modifying treatments. However, it is important that the potential of stem cells to treat neurological disease is critically appraised if the hopes of patients and doctors are not to be raised without foundation.