bluuebunny/crossref_metadata_2025 huggingface dataset:
The use of comparative genomic hybridization to characterize genome dynamics and diversity among the serotypes of Shigella
Authors: Peng Junping , Zhang Xiaobing , Yang Jian , Wang Jing , Yang E , Bin Wen , Wei Candong , Sun Meisheng , Jin Qi
Published: September 2006

Background

Compelling evidence indicates that Shigella species, the etiologic agents of bacillary dysentery, as well as enteroinvasive Escherichia coli, are derived from multiple origins of Escherichia coli and form a single pathovar. To further understand the genome diversity and virulence evolution of Shigella, comparative genomic hybridization microarray analysis was employed to compare the gene content of E. coli K-12 with those of 43 Shigella strains from all lineages.

Results

For the 43 strains subjected to CGH microarray analyses, the common backbone of the Shigella genome was estimated to contain more than 1,900 open reading frames (ORFs), with a mean number of 726 undetectable ORFs. The mosaic distribution of absent regions indicated that insertions and/or deletions have led to the highly diversified genomes of pathogenic strains.

Conclusion

These results support the hypothesis that by gain and loss of functions, Shigella species became successful human pathogens through convergent evolution from diverse genomic backgrounds. Moreover, we also found many specific differences between different lineages, providing a window into understanding bacterial speciation and taxonomic relationships.
Patterns of clinical presentation of adult coeliac disease in a rural setting
Authors: Jones Sián , D'Souza Charles , Haboubi Nadim Y
Published: September 2006

Background

In recent years there has been increasing recognition that the pattern of presentation of coeliac disease may be changing. The classic sprue syndrome with diarrhoea and weight loss may be less common than the more subtle presentations of coeliac disease such as an isolated iron deficiency anaemia. As a result, the diagnosis of this treatable condition is often delayed or missed. Recent serologic screening tests allow non-invasive screening to identify most patients with the disease and can be applied in patients with even subtle symptoms indicative of coeliac disease. Both benign and malignant complications of coeliac disease can be avoided by early diagnosis and a strict compliance with a gluten free diet.

Aim

The aim of this study is to evaluate the trends in clinical presentation of patients diagnosed with adult coeliac disease. In addition, we studied the biochemical and serological features and the prevalence of associated conditions in patients with adult coeliac disease.

Methods

This is an observational, retrospective, cross-sectional review of the medical notes of 32 adult patients attending the specialist coeliac clinic in a district general hospital.

Results

Anaemia was the most common mode of presentation accounting for 66% of patients. Less than half of the patients had any of the classical symptoms of coeliac disease and 25% had none of the classical symptoms at presentation. Anti-gliadin antibodies, anti-endomysial antibody and anti-tissue transglutaminase showed 75%, 68% and 90% sensitivity respectively. In combination, serology results were 100% sensitive as screening tests for adult coeliac disease. Fifty nine percent patients had either osteoporosis or osteopenia. There were no malignant complications observed during the follow up of our patients.

Conclusion

Most adults with coeliac disease have a sub clinical form of the disease and iron deficiency anaemia may be its sole presenting symptom. Only a minority of adult coeliac disease patients present with classical mal-absorption symptoms of diarrhoea and weight loss. Patients with atypical form of disease often present initially to hospital specialists other than a gastro-enterologist. An awareness of the broad spectrum of presentations of adult coeliac disease, among doctors both in primary care and by the various hospital specialists in secondary care, is necessary to avoid delays in diagnosis. It is important to include serological screening tests for coeliac disease systematically in the evaluation of adult patients with unexplained iron deficiency anaemia or unexplained gastro-intestinal symptoms and in those who are considered to be at increased risk for coeliac disease.
Temperature sensitive influenza A virus genome replication results from low thermal stability of polymerase-cRNA complexes
Authors: Dalton Rosa M , Mullin Anne E , Amorim Maria Joao , Medcalf Elizabeth , Tiley Laurence S , Digard Paul
Published: September 2006

Background

The RNA-dependent RNA polymerase of Influenza A virus is a determinant of viral pathogenicity and host range that is responsible for transcribing and replicating the negative sense segmented viral genome (vRNA). Transcription produces capped and polyadenylated mRNAs whereas genome replication involves the synthesis of an alternative plus-sense transcript (cRNA) with unmodified termini that is copied back to vRNA. Viral mRNA transcription predominates at early stages of viral infection, while later, negative sense genome replication is favoured. However, the "switch" that regulates the transition from transcription to replication is poorly understood.

Results

We show that temperature strongly affects the balance between plus and minus-sense RNA synthesis with high temperature causing a large decrease in vRNA accumulation, a moderate decrease in cRNA levels but (depending on genome segment) either increased or unchanged levels of mRNA. We found no evidence implicating cellular heat shock protein activity in this effect despite the known association of hsp70 and hsp90 with viral polymerase components. Temperature-shift experiments indicated that polymerase synthesised at 41°C maintained transcriptional activity even though genome replication failed. Reduced polymerase association with viral RNA was seen in vivo and in confirmation of this, in vitro binding assays showed that temperature increased the rate of dissociation of polymerase from both positive and negative sense promoters. However, the interaction of polymerase with the cRNA promoter was particularly heat labile, showing rapid dissociation even at 37°C. This suggested that vRNA synthesis fails at elevated temperatures because the polymerase does not bind the promoter. In support of this hypothesis, a mutant cRNA promoter with vRNA-like sequence elements supported vRNA synthesis at higher temperatures than the wild-type promoter.

Conclusion

The differential stability of negative and positive sense polymerase-promoter complexes explains why high temperature favours transcription over replication and has implications for the control of viral RNA synthesis at physiological temperatures. Furthermore, given the different body temperatures of birds and man, these finding suggest molecular hypotheses for how polymerase function may affect host range.
Lipids in dendritic cell biology: messengers, effectors, and antigens
Authors: Thurnher Martin
Published: September 2006

Dendritic cells (DC) are the most professional APC, which induce and coordinate immune responses. The principal task of DC is T cell activation, although DC also interact with and regulate other cell types. The present review serves to illustrate the increasing evidence that lipids play an important role in DC biology. In addition to being fuel stores and structural components of cellular membranes such as in other cell types, lipids act as second messengers and as effectors throughout all steps of DC differentiation and regulate important DC functions. The recent finding that DC synthesize lipid antigens in response to bacterial stimulation and induce antibacterial, CD1-restricted T cells through antigenic mimicry further emphasizes the important role of lipids and DC at the blurring boundaries of innate and adaptive immunity.
A dynamic expression survey identifies transcription factors relevant in mouse digestive tract development
Authors: Choi Michael Y. , Romer Anthony I. , Hu Michael , Lepourcelet Maina , Mechoor Ambili , Yesilaltay Ayce , Krieger Monty , Gray Paul A. , Shivdasani Ramesh A.
Published: September 2006

Tissue-restricted transcription factors (TFs), which confer specialized cellular properties, are usually identified through sequence homology or cis-element analysis of lineage-specific genes; conventional modes of mRNA profiling often fail to report non-abundant TF transcripts. We evaluated the dynamic expression during mouse gut organogenesis of 1381 transcripts,covering nearly every known and predicted TF, and documented the expression of approximately 1000 TF genes in gastrointestinal development. Despite distinctive structures and functions, the stomach and intestine exhibit limited differences in TF genes. Among differentially expressed transcripts, a few are virtually restricted to the digestive tract, including Nr2e3,previously regarded as a photoreceptor-specific product. TFs that are enriched in digestive organs commonly serve essential tissue-specific functions, hence justifying a search for other tissue-restricted TFs. Computational data mining and experimental investigation focused interest on a novel homeobox TF, Isx,which appears selectively in gut epithelium and mirrors expression of the intestinal TF Cdx2. Isx-deficient mice carry a specific defect in intestinal gene expression: dysregulation of the high density lipoprotein (HDL) receptor and cholesterol transporter scavenger receptor class B, type I (Scarb1). Thus,integration of developmental gene expression with biological assessment, as described here for TFs, represents a powerful tool to investigate control of tissue differentiation.
ASYMMETRIC LEAVES1 and auxin activities converge to repressBREVIPEDICELLUSexpression and promote leaf development inArabidopsis
Authors: Hay Angela , Barkoulas Michalis , Tsiantis Miltos
Published: September 2006

Leaf development in higher plants requires the specification of leaf initials at the flanks of a pluripotent structure termed the shoot apical meristem. In Arabidopsis, this process is facilitated by negative interactions between class I KNOTTED1-like homeobox (KNOX) and ASYMMETRIC LEAVES1 (AS1) transcription factors, such that KNOX proteins are confined to the meristem and AS1 to leaf initials. Sites of leaf inception are also defined by local accumulation of the hormone auxin; however, it is unknown how auxin and AS1 activities are integrated to control leaf development. Here, we show that auxin and AS1 pathways converge to repress expression of the KNOX gene BREVIPEDICELLUS (BP) and thus promote leaf fate. We also demonstrate that regulated auxin gradients control leaf shape in a KNOX-independent fashion and that inappropriate KNOX activity in leaves perturbs these gradients, hence altering leaf shape. We propose that regulatory interactions between auxin, AS1 and KNOX activities may both direct leaf initiation and sculpt leaf form.
The γTuRC components Grip75 and Grip128 have an essential microtubule-anchoring function in theDrosophilagermline
Authors: Vogt Nina , Koch Iris , Schwarz Heinz , Schnorrer Frank , Nüsslein-Volhard Christiane
Published: September 2006

The γ-tubulin ring complex (γTuRC) forms an essential template for microtubule nucleation in animal cells. The molecular composition of theγTuRC has been described; however, the functions of the subunits proposed to form the cap structure remain to be characterized in vivo. In Drosophila, the core components of the γTuRC are essential for mitosis, whereas the cap component Grip75 is not required for viability but functions in bicoid RNA localization during oogenesis. The other cap components have not been analyzed in vivo. We report the functional characterization of the cap components Grip128 and Grip75. Animals with mutations in Dgrip128 or Dgrip75 are viable, but both males and females are sterile. Both proteins are required for the formation of distinct sets of microtubules, which facilitate bicoid RNA localization during oogenesis, the formation of the central microtubule aster connecting the meiosis II spindles in oocytes and cytokinesis in male meiosis. Grip75 and Grip128 anchor the axoneme at the nucleus during sperm elongation. We propose that Grip75 and Grip128 are required to tether microtubules at specific microtubule-organizing centers, instead of being required for general microtubule nucleation. The γTuRC cap structure may be essential only for non-centrosome-based microtubule functions.
Translational control ofregA, a key gene controlling cell differentiation inVolvox carteri
Authors: Babinger Karin , Hallmann Armin , Schmitt Rüdiger
Published: September 2006

The complete division of labour between the reproductive and somatic cells of the green alga Volvox carteri is controlled by three types of genes. One of these is the regA gene, which controls terminal differentiation of the somatic cells. Here, we examined translational control elements located in the 5′ UTR of regA, particularly the eight upstream start codons (AUGs) that have to be bypassed by the translation machinery before regA can be translated. The results of our systematic mutational, structural and functional analysis of the 5′ UTR led us to conclude that a ribosome-shunting mechanism - rather than leaky scanning, ribosomal reinitiation, or internal ribosome entry site(IRES)-mediated initiation - controls the translation of regA mRNA. This mechanism, which involves dissociation of the 40S initiation complex from the message, followed by reattachment downstream, in order to bypass a secondary structure block in the mRNA, was validated by deleting the predicted`landing site' (which prevented regA expression) and inserting a stable 64 nucleotide hairpin just upstream of this site (which did not prevent regA expression). We believe that this is the first report suggesting that translation of an mRNA in a green eukaryote is controlled by ribosome shunting.
Semaphorin 3d promotes cell proliferation and neural crest cell development downstream of TCF in the zebrafish hindbrain
Authors: Berndt Jason D. , Halloran Mary C.
Published: September 2006

Neural crest cells (NCCs) are pluripotent migratory cells that are crucial to the development of the peripheral nervous system, pigment cells and craniofacial cartilage and bone. NCCs are specified within the dorsal ectoderm and undergo an epithelial to mesenchymal transition (EMT) in order to migrate to target destinations where they differentiate. Here we report a role for a member of the semaphorin family of cell guidance molecules in NCC development. Morpholino-mediated knockdown of Sema3d inhibits the proliferation of hindbrain neuroepithelial cells. In addition, Sema3d knockdown reduces markers of migratory NCCs and disrupts NCC-derived tissues. Similarly, expression of a dominant-repressor form of TCF (ΔTCF) reduces hindbrain cell proliferation and leads to a disruption of migratory NCC markers. Moreover,expression of ΔTCF downregulates sema3d RNA expression. Finally, Sema3d overexpression rescues reduced proliferation caused byΔTCF expression, suggesting that Sema3d lies downstream of Wnt/TCF signaling in the molecular pathway thought to control cell cycle in NCC precursors.
An analysis of the Revised Olweus Bully/Victim Questionnaire using the Rasch measurement model
Authors: Kyriakides Leonidas , Kaloyirou Chrystalla , Lindsay Geoff
Published: September 2006

Background. Bullying is a problem in schools in many countries. There would be a benefit in the availability of a psychometrically sound instrument for its measurement, for use by teachers and researchers. The Olweus Bully/Victim Questionnaire has been used in a number of studies but comprehensive evidence on its validity is not available.

Aims. To examine the conceptual design, construct validity and reliability of the Revised Olweus Bully/Victim Questionnaire (OBVQ) and to provide further evidence on the prevalence of different forms of bullying behaviour.

Sample. All 335 pupils (160 [47.8%] girls; 175 [52.2%]) boys, mean age 11.9 years [range 11.2–12.8 years]), in 21 classes of a stratified sample of 7 Greek Cypriot primary schools.

Method. The OBVQ was administered to the sample. Separate scales were created comprising (a) the items of the questionnaire concerning the extent to which pupils are being victimized; and (b) those concerning the extent to which pupils express bullying behaviour. Using the Rasch model, both scales were analysed for reliability, fit to the model, meaning, and validity. Both scales were also analysed separately for each of two sample groups (i.e. boys and girls) to test their invariance.

Results. Analysis of the data revealed that the instrument has satisfactory psychometric properties; namely, construct validity and reliability. The conceptual design of the instrument was also confirmed. The analysis leads also to suggestions for improving the targeting of items against student measures. Support was also provided for the relative prevalence of verbal, indirect and physical bullying. As in other countries, Cypriot boys used and experienced more bullying than girls, and boys used more physical and less indirect forms of bullying than girls.

Conclusions. The OBVQ is a psychometrically sound instrument that measures two separate aspects of bullying, and whose use is supported for international studies of bullying in different countries. However, improvements to the questionnaire were also identified to provide increased usefulness to teachers tackling this significant problem facing schools in many countries.
Personal bests (PBs): A proposed multidimensional model and empirical analysis
Authors: Martin Andrew J.
Published: September 2006

Background. This study seeks to identify the cornerstones of personal bests (PBs) in the educational setting.

Aims. The study proposes a multidimensional PB model in which students are most likely to attain PBs on tasks/goals that are (1) specific, (2) challenging, (3) competitively self‐referenced, and (4) self‐improvement based.

Sample. The study draws upon data from 1,016 students from 5 Australian high schools.

Methods. The hypothesized 4‐factor structure, its invariance across gender and year‐level, and the predictive utility of PBs are tested using confirmatory factor analysis and structural equation models with particular focus on the contribution of a higher‐order PB construct to measures of persistence, class participation, educational aspirations, and enjoyment of school. The fundamental dimensions of the model are further tested using multidimensional scaling.

Results. The 4‐factor structure fit the data well and significantly predicted persistence, class participation, educational aspirations, and enjoyment of school. The multidimensional scaling indicates that the 4 component factors can be defined in terms of the dual extent to which they reflect a clear goal focus and a self‐improvement focus.

Conclusion. Discussion centres on a proposed ‘Quadriploar PB Model’ emanating from the data analysis and strategies educators can use to facilitate PBs in the classroom.
What goes well with physics? Measuring and altering the image of science
Authors: Kessels Ursula , Rau Melanie , Hannover Bettina
Published: September 2006

Background. In view of the shortage of students majoring in science, we examined the image of physics in terms of students' implicit, automatic associations with physics.

Aims. To describe the specific image of physics that might alienate students (difficulty, masculinity, heteronomy) and test an intervention for altering the image.

Samples. In Study 1 the sample consisted of 63 school students (11th grade) and in Study 2 the sample consisted of 71 undergraduates.

Methods. Study 1 measured participants' implicit associations between physics (relative to English) and the image dimensions of difficulty, masculinity and heteronomy, implicit attitudes towards and identification with physics using latency data (Implicit Association Test; IAT) and explicit attitudes using a questionnaire. Study 2 was an experimental treatment that required reading a text (treatment group) that emphasized the importance of discourse and creativity for science versus a school textbook for physics (control group). Dependent variables: implicit attitudes (IAT).

Results. Students in Study 1 associated physics (relative to English) more easily with words referring to difficulty (than to ease), to males (than to females), to heteronomy (than to self‐realization), to unpleasantness (relative to pleasant words) and to others (relative to words referring to self). The three image aspects of difficulty, masculinity and heteronomy predicted explicit attitudes. Participants in the treatment group in Study 2 showed a significant reduction of the IAT effects compared to the control group.

Conclusions. The findings indicate that students' negative explicit attitudes towards physics coincide with negative implicit associations about physics. An intervention addressing the alteration of implicit associations proved to be fruitful. Implications for science education are discussed.
Teachers' perceptions of remediation possibilities of Dutch students in special education
Authors: Bakker Joep T. A. , Bosman Anna M. T.
Published: September 2006

Background. Research suggests that referral practices of teachers in regular education are not only affected by the level of learning difficulties but also by student behaviour and the level of students' parental involvement in education. It was hypothesized that teachers maintain a notion of the ‘ideal’ student, who has relatively good academic skills, is well behaved and has highly involved parents.

Aims. The main question of this study was whether special‐education teachers' perceptions regarding remediation possibilities are similarly affected by student behaviour and the level of students' parental involvement.

Sample. Nineteen experienced Dutch school teachers in special education each evaluated four students: two with relatively high and two with relatively low academic performance.

Methods. Three questionnaires to assess learning difficulties, behavioural problems and the level of parental involvement were developed.

Results. Teachers' perceptions of remediation possibilities were related to the severity of the learning difficulties and academic skill. Academic skill, in turn, was strongly related to the perception of the children's behavioural problems and parental involvement, which, in turn, links the perception of remediation possibilities indirectly to children's behavioural problems and parental involvement.

Conclusions. Special education teachers may also hold an image of the ‘ideal’ student. Students with high academic achievement levels are perceived as having fewer behavioural problems and more highly involved parents than students with low academic achievement levels. Whether this is due to justified or unjustified teachers' perceptions is a matter for future research. What is important is that stereotyping of students (justly or not) poses a serious problem for the Dutch reintegration policy.
Profiles of children with specific reading comprehension difficulties
Authors: Cain Kate , Oakhill Jane
Published: September 2006

Background. Children with fluent and accurate word reading in the presence of poor text comprehension are impaired on a wide range of reading‐related tasks.

Aims. This study investigated the consistency of skill impairment in a sample of poor comprehenders to identify any fundamental skill weakness that (i) might be associated with poor text comprehension, and (ii) might lead to depressed reading development. An additional aim was to determine whether reading comprehension difficulties are associated with more general educational difficulties.

Sample. Twenty‐three poor comprehenders and 23 good comprehenders with age‐appropriate word reading accuracy were assessed when aged 8 years. Concurrent reading and language performance and reading, educational attainment and reasoning skills 3 years later are reported.

Methods. The following skills were assessed when aged 8 years: word reading, text comprehension, vocabulary, syntax, cognitive ability, working memory, comprehension subskills. Listening comprehension, SAT scores and reasoning scores at 11 years are also reported.

Results. There was no evidence for any fundamental skill weaknesses in the population of poor comprehenders at Time 1. However, poor vocabulary skills led to impaired growth in word reading ability and poor general cognitive ability led to impaired growth in comprehension. Poor comprehenders obtained lower SAT scores than did the good comprehenders at 11 years.

Conclusions. These findings indicate that a single underlying source of poor comprehension is unlikely. Poor comprehenders are at risk of generally poor educational attainment, although weak verbal or cognitive skills appear to affect the reading development of poor comprehenders in different ways.
Assessment matters: Issues in the measurement of reading comprehension
Authors: Cain Kate , Oakhill Jane
Published: September 2006

Background. The Neale Analysis of Reading Ability (NARA; Neale, 1997) is a widely used assessment of reading comprehension and word reading accuracy. Spooner, Baddeley, and Gathercole (2004) questioned the suitability of the NARA for identifying children with specific reading comprehension deficits.

Aims and methods. An evaluation of the NARA measurement of word reading and reading comprehension level was undertaken in relation to models of reading ability. Appropriate control measures were considered. The strengths and weaknesses of different forms of reading comprehension were also evaluated.

Results. Previous research into reading comprehension difficulties using the NARA has adopted satisfactory control measures in relation to word reading ability. There are limitations associated with all the considered forms of reading comprehension assessment.

Conclusions. If administered and interpreted appropriately, the NARA is an effective instrument for researchers and practitioners who need to assess both word reading accuracy and reading comprehension and to identify children with a dissociation between these two aspects of reading.
Self‐construal and social comparison effects
Authors: Cheng Rebecca Wing‐yi , Lam Shui‐fong
Published: September 2006

Background. Social comparison research usually demonstrates that students will have higher self‐evaluation in downward comparison but lower self‐evaluation in upward comparison. However, the existence of this contrast effect may depend on people's self‐construal. The contrast effect may exist only for people with independent self‐construal. For people with interdependent self‐construal, the contrast effect may be attenuated.

Aim. The study investigated the role of self‐construal as a moderator of the social comparison effects in authentic classrooms.

Sample. The participants were 96 Chinese seventh‐grade students (41 male, 51 female and 4 unreported) from a secondary school in Hong Kong.

Method. The experiment employed a 2 × 2 between‐subjects design based on 2 levels of self‐construal (independent, interdependent) and 2 levels of comparison standard (upward comparison, downward comparison). The dependent variable was students' self‐evaluation.

Results. A two‐way ANOVA indicated a significant interaction between self‐construal and comparison standard on self‐evaluation. When the students' independent self‐construal was activated, they reported higher self‐evaluation in downward comparison but lower self‐evaluation in upward comparison. However, such a contrast effect was attenuated when the students' interdependent self‐construal was activated. They reported high self‐evaluation in both upward and downward comparisons.

Conclusions. The outcome of social comparison depends on whether independent or interdependent self‐construal is salient in the classroom.
The validity of physical aggression in predicting adolescent academic performance
Authors: Loveland James M. , Lounsbury John W. , Welsh Deborah , Buboltz Walter C.
Published: September 2006

Background. Aggression has a long history in academic research as both a criterion and a predictor variable and it is well documented that aggression is related to a variety of poor academic outcomes such as: lowered academic performance, absenteeism and lower graduation rates. However, recent research has implicated physical aggression as being predictive of lower academic performance.

Aims. The purpose of this study was to examine the role of the ‘Big Five’ personality traits of agreeableness, openness to experience, conscientiousness, neuroticism and extraversion and physical aggression in predicting the grade point averages (GPA) of adolescent students and to investigate whether or not there were differences in these relationships between male and female students.

Sample. A sample of 992 students in grades 9 to 12 from a high school in south‐eastern USA as part of a larger study examining the students' preparation for entry into the workforce.

Method. The study was correlational in nature: students completed a personality inventory developed by the second author with the GPA information supplied by the school.

Results. Results indicated that physical aggression accounts for 16% of variance in GPA and it adds 7% to the prediction of GPA beyond the Big Five. The Big Five traits added only 1.5% to the prediction of GPA after controlling for physical aggression. Interestingly, a significantly larger amount of variance in GPA was predicted by physical aggression for females than for males.

Conclusions. Aggression accounts for significantly more variance in the GPA of females than for males, even when controlling for the Big Five personality factors. Future research should examine the differences in the expression of aggression in males and females, as well as how this is affecting interactions between peers and between students and their teachers.
The effects of Peer Mediation with Young Children (PMYC) on children's cognitive modifiability
Authors: Tzuriel David , Shamir Adina
Published: September 2006

Peer mediation with young children is a relatively novel approach aimed at teaching young children how to mediate to their peers. The main benefits of peer mediation are in developing children's mediation teaching style and cognitive modifiability. The peer mediation developed recently is based on Vygotsky's sociocultural and Feuerstein'smediated learning experiencetheories. The main objectives of the study were to investigate the effects of the Peer Mediation with Young Children (PMYC) programme on children's cognitive modifiability of mediators and learners and to study the effects of cognitive level of the learner and mediator on their cognitive modifiability following the programme. A sample of 178 pupils (89 mediators in Grade 3 and 89 learners in Grade 1) was randomly assigned to experimental (N=43 dyads) and control (N=46 dyads) groups. The mediators in the experimental group participated in the PMYC programme, whereas the mediators in the control group received a substitute intervention aimed at emphasizing general conditions of peer interaction. Following the intervention, mediators of both groups received a demonstration of a multimedia programme as a preparation for the peer mediation interaction and later taught it to their young counterparts. Following the teaching session (e.g. teaching of seriation problems), mediators in both groups were given a dynamic assessment measure of analogies. The learners however were given a test of seriation before and after the intervention. The findings showed that following the intervention the experimental mediators showed higher level of analogies scores, as well as higher improvement on the dynamic analogies measure as compared with control mediators. The experimental learners showed higher pre‐ to post‐intervention achievements on the seriation problems as compared with control learners. The findings showed also that when there was a match between the mediator and learner's cognitive level (i.e. low–low or high–high) the differences between the experimental and control groups were minor and negligible. However, when the mediator‐learner cognitive levels did not match, the experimental learners received higher scores than the control learners. Mediators in the experimental group had to cope with the incongruent cognitive level by facilitating their mediational approach and consequently enhancing the learner's performance. The findings are discussed in regard to Piaget, Vygotsky and Feuerstein's theories and recent research on peer assisted learning.
Using a multitrait‐multimethod analysis to examine conceptual similarities of three self‐regulated learning inventories
Authors: Muis Krista R. , Winne Philip H. , Jamieson‐Noel Dianne
Published: September 2006

Background. A programme of construct validity research is necessary to clarify previous research on self‐regulation and to provide a stronger basis for future research.

Aim. A multitrait‐multimethod (MTMM) analysis was conducted to assess convergent and discriminant validity of three self‐regulation measures: the Learning and Study Strategies Inventory (LASSI; Weinstein, 1987), the Motivated Strategies for Learning Questionnaire (MSLQ; Pintrich, Smith, Garcia, & McKeachie, 1993) and the Meta‐cognitive Awareness Inventory (MAI; Schraw & Dennison, 1994). Method bias across all three inventories was also examined.

Sample and method. Three hundred and eighteen undergraduate university students (255 female, 61 male, 2 did not specify) were recruited from various courses to participate in research on perceptions about studying and study methods. Participants spent 30–60 minutes completing all three inventories.

Results. Evidence for convergent validity was found at the matrix level, but was attenuated when examined at the individual parameter level. Evidence for discriminant validity among traits was modest, and common method bias was evident across all three measures.

Conclusions. Results revealed the three inventories yielded different results, which suggests that researchers should be selective in the inventory they use to assess self‐regulated learning (SRL).
Collaborative philosophical enquiry for school children: Cognitive effects at 10–12 years
Authors: Topping K. J. , Trickey S.
Published: September 2006

Background. Debates about the modifiability of cognitive ability have been largely resolved by reports of successful ‘thinking skills’ interventions. However, such interventions are very diverse and generalization of effects relatively little explored.

Aims. This study investigated whether a thinking skills intervention involving collaborative interactive dialogue could lead not only to gains in measured verbal cognitive ability but also generalization to non‐verbal and quantitative reasoning ability.

Sample. Randomly selected intervention children were aged 10 at pre‐test (N = 105, four classes/schools). Controls followed a normal curriculum (N = 72, three classes/two schools).

Method. Intervention children engaged in collaborative enquiry for 1 hour per week over 16 months. The control group received normal classroom experiences. The Cognitive Abilities Test was administered before and after the intervention.

Results. Intervention pupils showed significant standardized gains in verbal and also in non‐verbal and quantitative aspects of reasoning, consistent across intervention schools. Boys and girls made significant gains. The highest quartile of pre‐test ability showed the smallest gains. Controls did not gain in any aspect.

Conclusions. Philosophical enquiry involving interactive dialogue led not only to significant gains in measured verbal cognitive ability but also generalization to non‐verbal and quantitative reasoning ability, consistent across schools and largely irrespective of pupil gender and ability. The effect sizes from this large‐scale field trial in one local authority exceeded those reported in the literature. Implications for theory building, replicability and sustainability are addressed.
Bullies and victims at school: Are they the same pupils?
Authors: Solberg Mona E. , Olweus Dan , Endresen Inger M.
Published: September 2006

Background. The reported prevalence of bully‐victims and aggressive/provocative victims varies quite considerably in previous research, and only a few studies have reported prevalence rates across grades. There is also a lack of detailed analyses of the extent to which victims are also bullies, and bullies are also victims.

Aims. To study the prevalence of male and female bully‐victims across grade/age and to establish the degree of overlap or relative size of the bully‐victim group by relating them to all victims, all bullies and all involved students.

Samples. Participants in Study 1 were 5,171 pupils in grades 5–9 from 37 schools. Study 2 comprised 12,983 pupils in grades 4–10 from 66 schools.

Methods. The Olweus Bully/Victim Questionnaire was administered to the pupils in their ordinary classrooms.

Results. The prevalence of bully‐victims was low and mainly declined across grades. There were far more boys than girls in the bully‐victim group. Bully‐victims resembled victims only (pure victims) in terms of age‐trends and bullies only (pure bullies) in terms of sex composition. The overlap of bully‐victims with the total victim group was fairly small (10–20%) in all grades. In primary grades, bully‐victims constituted about 30–50% of the total bully group, whereas in higher grades these proportions were considerably lower.

Conclusion. Our analyses and overview of previous research suggest that the bully‐victim group is small, and that the large variations across studies are mainly due to differences in choice of cutoff point. Bully‐victims should generally be seen and treated statistically as a distinct subgroup. The relatively larger proportion of bully‐victims in lower grades should be explored further.
Stereotype threat in classroom settings: The interactive effect of domain identification, task difficulty and stereotype threat on female students' maths performance
Authors: Keller Johannes
Published: September 2006

Background. Stereotype threat research revealed that negative stereotypes can disrupt the performance of persons targeted by such stereotypes. This paper contributes to stereotype threat research by providing evidence that domain identification and the difficulty level of test items moderate stereotype threat effects on female students' maths performance.

Aims. The study was designed to test theoretical ideas derived from stereotype threat theory and assumptions outlined in the Yerkes–Dodson law proposing a nonlinear relationship between arousal, task difficulty and performance.

Sample. Participants were 108 high school students attending secondary schools.

Method. Participants worked on a test comprising maths problems of different difficulty levels. Half of the participants learned that the test had been shown to produce gender differences (stereotype threat). The other half learned that the test had been shown not to produce gender differences (no threat). The degree to which participants identify with the domain of maths was included as a quasi‐experimental factor.

Results. Maths‐identified female students showed performance decrements under conditions of stereotype threat. Moreover, the stereotype threat manipulation had different effects on low and high domain identifiers' performance depending on test item difficulty. On difficult items, low identifiers showed higher performance under threat (vs. no threat) whereas the reverse was true in high identifiers. This interaction effect did not emerge on easy items.

Conclusions. Domain identification and test item difficulty are two important factors that need to be considered in the attempt to understand the impact of stereotype threat on performance.
Predicting academic self‐handicapping in different age groups: The role of personal achievement goals and social goals
Authors: Leondari Angeliki. , Gonida Eleftheria.
Published: September 2006

Background. Academic self‐handicapping refers to the use of impediments to successful performance on academic tasks. Previous studies have shown that it is related to personal achievement goals. A performance goal orientation is a positive predictor of self‐handicapping, whereas a task goal orientation is unrelated to self‐handicapping.

Aims. The aim of this study was to examine the relationship between academic self‐handicapping, goal orientations (task, performance‐approach, performance‐avoidance), social goals, future consequences and achievement in mathematics. An additional aim was to investigate grade‐level and gender differences in relation to academic self‐handicapping.

Sample. Participants were 702 upper elementary, junior and senior high school students with approximately equal numbers of girls and boys.

Results. There were no grade‐level or gender differences as regards the use of self‐handicapping. The correlations among the variables revealed that, when the whole sample was considered, self‐handicapping was positively related to performance goal orientations and pleasing significant others and negatively to achievement in mathematics. The results of hierarchical regression analysis showed that, in upper elementary and junior high schools, the association between achievement in mathematics and self‐handicapping was mediated by performance‐avoidance goals. In senior high school, only task goal orientation was a negative predictor of self‐handicapping.
Future goal setting, task motivation and learning of minority and non‐minority students in Dutch schools
Authors: Andriessen Iris , Phalet Karen , Lens Willy
Published: September 2006

Background. Cross‐cultural research on minority school achievement yields mixed findings on the motivational impact of future goal setting for students from disadvantaged minority groups. Relevant and recent motivational research, integrating Future Time Perspective Theory with Self‐Determination Theory, has not yet been validated among minority students.

Aims. To replicate across cultures the known motivational benefits of perceived instrumentality and internal regulation by distant future goals; to clarify when and how the future motivates minority students' educational performance.

Sample. Participants in this study were 279 minority students (100 of Turkish and 179 of Moroccan origin) and 229 native Dutch students in Dutch secondary schools.

Methods. Participants rated the importance of future goals, their perceptions of instrumentality, their task motivation and learning strategies. Dependent measures and their functional relations with future goal setting were simultaneously validated across minority and non‐minority students, using structural equation modelling in multiple groups.

Results. As expected, Positive Perceived Instrumentality for the future increases task motivation and (indirectly) adaptive learning of both minority and non‐minority students. But especially internally regulating future goals are strongly related to more task motivation and indirectly to more adaptive learning strategies.

Conclusion. Our findings throw new light on the role of future goal setting in minority school careers: distant future goals enhance minority and non‐minority students' motivation and learning, if students perceive positive instrumentality and if their schoolwork is internally regulated by future goals.
Thirty years on – a large anti‐Flynn effect? The Piagetian test Volume & Heaviness norms 1975–2003
Authors: Shayer Michael , Ginsburg Denise , Coe Robert
Published: September 2006

Background. Volume & Heaviness was one of three Piagetian tests used in the CSMS survey in 1975/76. However unlike psychometric tests showing the Flynn effect – that is with students showing steady improvements year by year requiring tests to be restandardized – it appeared that the performance of Y7 students has recently been getting steadily worse.

Aims. A sample of schools sufficiently large and representative was chosen so that the hypothesis of worsening performance could be tested, and estimated quantitatively.

Sample. Sixty‐nine Y7 school year groups containing pupil data on the Volume & Heaviness test and the University of Durham CEM Centre MidYIS test were located giving a sample of 10, 023 students covering the years 2000 to 2003.

Method. Regression of the students' school mean on Volume & Heaviness on the schools' mean MidYIS 1999 standardized score, and computing the regression at MidYS = 100 allows comparison with that found in 1976.

Results. The mean drops in scores from 1976 to 2003 were boys = 1.13 and girls = 0.6 levels. A differential of 0.50 standard deviations in favour of boys in 1976 had completely disappeared by the year 2002. Between 1976 and 2003 the effect‐size of the drop in the boys' performance was 1.04 standard deviations, and for girls was 0.55 standard deviations.

Conclusion. The idea that children leaving primary school are getting more and more intelligent and competent – whether it is viewed in terms of the Flynn effect, or in terms of government statistics on performance in Key Stage 2 SATS in mathematics and science – is put into question by these findings.
Adaptive robust estimation and testing
Authors: Keselman H. J. , Wilcox Rand R. , Lix Lisa M. , Algina James , Fradette Katherine
Published: September 2006

We examined nine adaptive methods of trimming, that is, methods that empirically determine when data should be trimmed and the amount to be trimmed from the tails of the empirical distribution. Over the 240 empirical values collected for each method investigated, in which we varied the total percentage of data trimmed, sample size, degree of variance heterogeneity, pairing of variances and group sizes, and population shape, one method resulted in exceptionally good control of Type I errors. However, under less extreme cases of non‐normality and variance heterogeneity a number of methods exhibited reasonably good Type I error control. With regard to the power to detect non‐null treatment effects, we found that the choice among the methods depended on the degree of non‐normality and variance heterogeneity. Recommendations are offered.
Hypothesis tests for population heterogeneity in meta‐analysis
Authors: Viechtbauer Wolfgang
Published: September 2006

Choice of the appropriate model in meta‐analysis is often treated as an empirical question which is answered by examining the amount of variability in the effect sizes. When all of the observed variability in the effect sizes can be accounted for based on sampling error alone, a set of effect sizes is said to be homogeneous and a fixed‐effects model is typically adopted. Whether a set of effect sizes is homogeneous or not is usually tested with the so‐calledQtest. In this paper, a variety of alternative homogeneity tests – the likelihood ratio, Wald and score tests – are compared with theQtest in terms of their Type I error rate and power for four different effect size measures. Monte Carlo simulations show that theQtest kept the tightest control of the Type I error rate, although the results emphasize the importance of large sample sizes within the set of studies. The results also suggest under what conditions the power of the tests can be considered adequate.
Two item response theory models for analysing normative forced‐choice personality items
Authors: Ferrando Pere J.
Published: September 2006

This paper proposes two unidimensional item response theory (IRT) models for analysing normative forced‐choice personality items. Both models are derived from a common theoretical framework and arise as a result of different assumptions regarding the mechanism of choice. The simplest mechanism gives rise to the one‐parameter normal‐ogive model. The second mechanism gives rise to a new IRT model, which is closely related to the Coombs–Zinnes probabilistic unfolding model. The second model is compared theoretically to the normal‐ogive model in terms of item characteristic curves and amount of item information. Next, procedures for estimating the respondent and the item parameters in the second model are described. Finally, both models are empirically compared by using two well‐known personality measures.