bluuebunny/crossref_metadata_2025 huggingface dataset:
Administration of antibiotics via the respiratory tract for the prevention of ICU-acquired pneumonia: a meta-analysis of comparative trials
Authors: Falagas Matthew E , Siempos Ilias I , Bliziotis Ioannis A , Michalopoulos Argyris
Published: September 2006

Introduction

The administration of prophylactic antibiotics via the respiratory tract is one of several strategies for the prevention of intensive care unit (ICU)-acquired pneumonia. We systematically examined the available evidence regarding the effect of prophylactic antibiotics administered via the respiratory tract on the development of ICU-acquired pneumonia, mortality, colonization of the respiratory tract, emergence of antimicrobial resistance, and toxicity.

Methods

We searched the PubMed database (January 1950 to September 2005) and references from relevant articles to identify trials that provided comparative data regarding the above-mentioned outcomes. Two investigators independently performed the data extraction to calculate the effect of the studied intervention on clinically relevant outcomes.

Results

Our meta-analysis includes 8 comparative trials (5 randomized controlled trials (RCTs) and 3 non-randomized trials) studying gentamicin (3 trials), polymyxins (3 trials), tobramycin (1 trial), and ceftazidime (1 trial) that studied 1,877 patients. Our primary analysis, which included the 5 RCTs, revealed that ICU-acquired pneumonia was less common in the group of patients that received the antibiotic prophylaxis (odds ratio (OR) = 0.49, 95% confidence interval (CI) 0.32–0.76). No difference in mortality was found between the compared groups (OR = 0.86, 95% CI 0.55–1.32). Data were too limited to permit an analysis of colonization with Pseudomonas aeruginosa. A secondary analysis, adding the three non-randomized comparative trials, did not reveal substantially different results regarding ICU-acquired pneumonia and mortality, while fewer patients were colonized with P. aeruginosa in the group that received prophylaxis, compared to the group of patients that received no prophylaxis (OR = 0.51, 95% CI 0.30–0.86). No serious drug-related toxicity was noted. No meaningful systematic analysis of the evidence regarding the emergence of resistance could be performed in the studies included in our meta-analysis.

Conclusion

The limited available evidence supports that prophylactic administration of antibiotics via the respiratory tract is associated with reduction of occurrence of ICU-acquired pneumonia. However, there is evidence from non-comparative studies that this preventive strategy may lead to an increase in the emergence of resistant bacteria. Thus, further investigation, at least in ICU patients at high risk for development of ICU-acquired pneumonia, is warranted, including a more systematic evaluation of issues related to the emergence of resistance.
Length of Stay by Route of Contrast Administration for Diagnosis of Appendicitis by Computed‐tomography Scan
Authors: Berg Evan R. , Mehta Supriya D. , Mitchell Patricia , Soto Jorge , Oyama Leslie , Ulrich Andrew
Published: September 2006

Objectives Studies show equivalent accuracy of abdominal computed tomography (CT) using rectal contrast compared with oral contrast for diagnosing appendicitis. The authors evaluated whether emergency department (ED) length of stay and satisfaction differed by route of contrast administration for abdominal CT.

Methods This before‐and‐after intervention evaluated adult patients in an urban academic ED who were undergoing abdominal CT to screen for suspected appendicitis. Phase 1 subjects had a CT after oral contrast. Phase 2 patients had a CT after rectal contrast infused by gravity drip. Patients were interviewed after CT scan to assess satisfaction and discomfort. The primary outcome was ED length of stay. Medians, 95% binomial confidence intervals (CI), and Wilcoxon rank sum test of differences were calculated.

Results One hundred twelve patients were enrolled; half received rectal contrast. There was a significant decrease in length of stay for patients who were administered rectal contrast (261 min, 95% CI = 236 to 305 min) vs. oral contrast (332 min, 95% CI = 299 to 362 min), p = 0.009. Although subjects in the rectal‐contrast group waited 65 minutes longer than did oral‐contrast patients before receiving contrast after the CT order, the time from contrast administration to CT was 13 minutes, vs. 150 minutes for patients receiving oral contrast (p < 0.001). Patient satisfaction and discomfort did not differ by route of contrast administration.

Conclusions Rectal contrast for patients undergoing abdominal CT to rule out appendicitis reduced ED length of stay by more than an hour and did not affect patient satisfaction or discomfort. Rectal‐contrast administration for abdominal CT may significantly shorten patient throughput time for individuals undergoing evaluation for appendicitis.
Digital versus Local Anesthesia for Finger Lacerations: A Randomized Controlled Trial
Authors: Chale Stuart , Singer Adam J. , Marchini Scott , McBride Mary Jo , Kennedy David
Published: September 2006

Objectives To compare the pain of needle insertion, anesthesia, and suturing in finger lacerations after local anesthesia with prior topical anesthesia with that experienced after digital anesthesia.

Methods This was a randomized controlled trial in a university‐based emergency department (ED), with an annual census of 75,000 patient visits. ED patients aged ≥8 years with finger lacerations were enrolled. After standard wound preparation and 15‐minute topical application of lidocaine‐epinephrine‐tetracaine (LET) in all wounds, lacerations were randomized to anesthesia with either local or digital infiltration of 1% lidocaine. Pain of needle insertion, anesthetic infiltration, and suturing were recorded on a validated 100‐mm visual analog scale (VAS) from 0 (none) to 100 (worst); also recorded were percentage of wounds requiring rescue anesthesia; time until anesthesia; percentage of wounds with infection or numbness at day 7. Outcomes were compared by using Mann‐Whitney U and chi‐square tests. A sample of 52 patients had 80% power to detect a 15‐mm difference in pain scores.

Results Fifty‐five patients were randomized to digital (n= 28) or local (n= 27) anesthesia. Mean age (±SD) was 38.1 (±16.8) years, 29% were female. Mean (±SD) laceration length and width were 1.7 (±0.7) cm and 2.0 (±1.0) mm, respectively. Groups were similar in baseline patient and wound characteristics. There were no between‐group differences in pain of needle insertion (mean difference, 1.3 mm; 95% confidence interval [CI] =−17.0 to 14.3 mm); anesthetic infiltration (mean difference, 2.3 mm; 95% CI =−19.7 to 4.4 mm), or suturing (mean difference, 7.6 mm; 95% CI =−3.3 to 21.1 mm). Only one patient in the digital anesthesia group required rescue anesthesia. There were no wound infections or persistent numbness in either group.

Conclusions Digital and local anesthesia of finger lacerations with prior application of LET to all wounds results in similar pain of needle insertion, anesthetic infiltration, and pain of suturing.
Prognostic Value of Symptoms during a Normal or Nonspecific Electrocardiogram in Emergency Department Patients with Potential Acute Coronary Syndrome
Authors: Chase Maureen , Brown Aaron M. , Robey Jennifer L. , Pollack Charles V. , Shofer Frances S. , Hollander Judd E.
Published: September 2006

Objectives Emergency department (ED) patients with symptoms concerning for acute coronary syndrome (ACS) and a normal electrocardiogram (ECG) are at risk for adverse cardiovascular events. The authors hypothesized that patients with a normal or nonspecific ECG during symptoms have a lower risk for ACS than do those who are asymptomatic.

Methods This was a prospective cohort study of ED patients with potential ACS. Outcomes were acute myocardial infarction (AMI), ACS, and 30‐day cardiovascular events (death, AMI, revascularization). Fisher's exact test, t‐tests, and logistic regression were used for data analysis.

Results Of 2,593 patient visits, 2,007 patients had normal or nonspecific ECG findings. There were 1,196 who had symptoms during ECG, whereas 811 did not. Patients with symptoms at ECG acquisition were younger (49.9 vs. 55.2 years; p < 0.001) and were more likely to be black (70% vs. 64%; p = 0.002), female (63% vs. 58%; p = 0.03), and to have used cocaine (5% vs. 2%; p = 0.004). They were less likely to have hypertension (49% vs. 58%; p < 0.001), and diabetes (22% vs. 17%; p = 0.002). Patients with and without symptoms were equally likely to have AMI (both 2.8%; p > 0.99), ACS (10.1% vs. 11.5%; p = 0.34), and 30‐day adverse outcomes (both 5.3%; p > 0.99). After adjustment for baseline cardiovascular‐risk factors, odds ratios for patients with symptoms at the time of ECG acquisition were not significantly different for any of the outcomes: AMI (1.1; 95% confidence interval [CI] = 0.6 to 1.9); ACS (1.1; 95% CI = 0.8 to 1.4); or 30‐day events (1.2; 95% CI = 0.8 to 1.9).

Conclusions Patients who are symptomatic during acquisition of a normal or nonspecific ECG have rates of adverse cardiovascular events similar to those of patients without symptoms. Clinicians should not rely on the absence of ECG abnormalities during symptoms to help exclude ACS.
R‐wave Amplitude in Lead II of an Electrocardiograph Correlates with Central Hypovolemia in Human Beings
Authors: McManus John G. , Convertino Victor A. , Cooke William H. , Ludwig David A. , Holcomb John B.
Published: September 2006

Objectives Previous animal and human experiments have suggested that reduction in central blood volume either increases or decreases the amplitude of R waves in various electrocardiograph (ECG) leads depending on underlying pathophysiology. In this investigation, we used graded central hypovolemia in adult volunteer subjects to test the hypothesis that moderate reductions in central blood volume increases R‐wave amplitude in lead II of an ECG.

Methods A four‐lead ECG tracing, heart rate (HR), estimated stroke volume (SV), systolic blood pressure, diastolic blood pressure, and mean arterial pressure were measured during baseline supine rest and during progressive reductions of central blood volume to an estimated volume loss of >1,000 mL with application of lower‐body negative pressure (LBNP) in 13 healthy human volunteer subjects.

Results Lower‐body negative pressure resulted in a significant progressive reduction in central blood volume, as indicated by a maximal decrease of 65% in SV and maximal elevation of 56% in HR from baseline to −60 mm Hg LBNP. R‐wave amplitude increased (p < 0.0001) linearly with progressive LBNP. The amalgamated correlation (R2) between average stroke volume and average R‐wave amplitude at each LBNP stage was −0.989.

Conclusions These results support our hypothesis that reduction of central blood volume in human beings is associated with increased R‐wave amplitude in lead II of an ECG.
The role of Tudor domains in germline development and polar granule architecture
Authors: Arkov Alexey L. , Wang Ju-Yu S. , Ramos Andres , Lehmann Ruth
Published: September 2006

Tudor domains are found in many organisms and have been implicated in protein-protein interactions in which methylated protein substrates bind to these domains. Here, we present evidence for the involvement of specific Tudor domains in germline development. Drosophila Tudor, the founder of the Tudor domain family, contains 11 Tudor domains and is a component of polar granules and nuage, electron-dense organelles characteristic of the germline in many organisms, including mammals. In this study, we investigated whether the 11 Tudor domains fulfil specific functions for polar granule assembly,germ cell formation and abdomen formation. We find that even a small number of non-overlapping Tudor domains or a substantial reduction in overall Tudor protein is sufficient for abdomen development. In stark contrast, we find a requirement for specific Tudor domains in germ cell formation, Tudor localization and polar granule architecture. Combining genetic analysis with structural modeling of specific Tudor domains, we propose that these domains serve as `docking platforms' for polar granule assembly.
Two independently selected capping ribozymes share similar substrate requirements
Authors: Zaher Hani S. , Watkins R. Ammon , Unrau Peter J.
Published: September 2006

We report the isolation and characterization of a second capping ribozyme, called 6.17. This ribozyme has substrate requirements that are very similar to a previously isolated capping ribozyme called Iso6. Both ribozymes promote capping and cap exchange reactions with a broad range of nucleotide substrates. The ribozymes mediate a reaction where the terminal phosphate of the nucleotide substrate attacks the α-phosphate found at the ribozyme's 5′ terminus. This reaction involves the release of pyrophosphate during capping or a nucleotide during cap exchange. The second-order rate constants for 6.17 and Iso6 depend strongly on the length of the phosphate group found on the nucleotide substrate. Nucleoside diphosphates or triphosphates are efficiently utilized, while monophosphates are used ∼20-fold less efficiently by both ribozymes. These ribozymes also have rates that increase as pH is decreased. Despite these similarities, the ribozymes are not identical and 6.17 performs optimally when incubated with divalent magnesium ions, while Iso6 displays a preference for calcium ions. Further, the ribozymes have globally different secondary structures; 6.17 has a complicated pseudoknot structure consisting of five helical elements, while Iso6 likely consists of four helical elements. We hypothesize that capping proceeds via an invariant phosphate dependent mechanism that imposes a nearly identical “catalytic fingerprint” on these two distinct ribozymes.
Earning and learning: Role congruence, state/trait factors and adjustment to university life
Authors: Swanson Vivien , Broadbridge Adelina , Karatzias Athanasios
Published: September 2006

Background. Undertaking term‐time employment is increasingly commonplace for university students. Much research suggests that combining ‘earning and learning’ may be detrimental to university life, generating role conflicts, increasing stress and reducing academic success, participation and overall adjustment to university. Potential positive effects of term‐time employment on well‐being are often neglected.

Aims. This study adopted a balanced perspective, investigating the relationship between role congruence in academic, social and career domains and adjustment, with state and trait psychological factors as mediators/moderators.

Methods. A questionnaire measuring perceived role congruence, adjustment to university life and psychological state and trait characteristics was mailed to all undergraduates at a Scottish university during term‐time.

Sample. Results for a subsample of 625 university students currently in term‐time employment were included in this paper.

Results. Findings suggested that students generally perceived employment and university roles to be in balance, and there was no difference in adjustment for students whether currently in term‐time employment or not. However, psychological factors, particularly positive affectivity and stress were important mediators of the relationship between role congruence and adjustment.

Conclusions. Since promoting role congruence may enhance students' adjustment and well‐being, the study has implications for universities, student welfare organizations and employers offering term‐time employment.
The effects of an early history of otitis media on children's language and literacy skill development
Authors: Winskel Heather
Published: September 2006

Background. Otitis media (OM) or middle ear infection is a common childhood illness and is most frequent during the crucial first 3 years of life when speech and language categories are being established, which could potentially have a long‐term effect on language and literacy skill development.

Aims. The purpose of the current study was to ascertain the effects of a history of OM in early childhood on later language and literacy skill development.

Sample. Forty‐three children from Grade 1 and Grade 2, between 6 and 8 years old with an early history of OM and 43 control children, matched for chronological age, gender and socio‐economic status, participated in this study.

Methods. Children were tested on multiple measures of phonological awareness, semantic knowledge, narration and reading ability. The performance of children with and without a history of OM was compared on the different measures.

Results. There was a general tendency for children with a history of OM to achieve lower scores on phonological awareness skills of alliteration, rhyme and non‐word reading, semantic skills of expressive vocabulary and word definitions and reading than non‐OM children.

Conclusion. These findings highlight the potential problems an early history of middle ear infection can have on school‐aged children's later language and literacy development.
Arithmetic problems at school: When there is an apparent contradiction between the situation model and the problem model
Authors: Coquin‐Viennot Danièle , Moreau Stéphanie
Published: September 2006

Background. Understanding and solving problems involves different levels of representation. On the one hand, there are logico‐mathematical representations, or problem models (PMs), which contain information such as ‘the size of the flock changed from 31 sheep to 42’ while, on the other hand, there are more qualitative representations, or qualitative situation models (QSMs), comprising events expressed in everyday terms, such as ‘a lot of lambs had been born’.

Aims. We set out to show that an apparent contradiction between a PM and a QSM can result in poorer performances, especially when the activation of formal representations is not fully automatic.

Sample. We tested 44 third years (mean age 8;6) and 46 fourth years (mean age 9; 8) from two primary schools in France.

Method. Change problems and compare problems were drafted in two versions: one where the QSM and PM were consistent and one where they appeared to be contradictory but were not (referred to hereafter as the inconsistent version). For example, if the numerical data proved that the size of a flock of sheep had increased (PM), the consistent version would state that a lot of lambs had been born (QSM), whereas the inconsistent version would state that the wolf had devoured some of the sheep (QSM). Each pupil was given 7 consistent problems and 7 ‘inconsistent’ ones to solve.

Results. For the change problems, errors were more frequent on the inconsistent versions, especially among the younger subjects. For the compare problems, there were more errors on the inconsistent versions regardless of the subjects' age.

Conclusion. It is in situations where the problem schema is not automatically activated (younger subjects or compare problems) that the QSM plays its role of intermediate representation and causes performances to deteriorate if it does not correspond to the PM.
The use of deep and surface learning strategies among students learning English as a foreign language in an Internet environment
Authors: Aharony Noa
Published: September 2006

Background. The learning context is learning English in an Internet environment. The examination of this learning process was based on the Biggs and Moore's teaching‐learning model (Biggs & Moore, 1993).

Aim. The research aims to explore the use of the deep and surface strategies in an Internet environment among EFL students who come from different socio‐economic backgrounds. The results of the research may add an additional level to the understanding of students' functioning in the Internet environment.

Sample. One hundred fourty‐eight Israeli junior and high school students participated in this research.

Methods. The methodology was based on special computer software: Screen Cam, which recorded the students' learning process. In addition, expert judges completed a questionnaire which examined and categorized the students' learning strategies.

Results. The research findings show a clear preference of participants from all socio‐economic backgrounds towards the surface learning strategy. The findings also showed that students from the medium to high socio‐economic background used both learning strategies more frequently than low socio‐economic students.

Conclusions. The results reflect the habits that students acquire during their adjustment process throughout their education careers. A brief encounter with the Internet learning environment apparently cannot change norms or habits, which were acquired in the non‐Internet learning environment.
The influence of achievement goals on the constructive activity of low achievers during collaborative problem solving
Authors: Gabriele Anthony J.
Published: September 2006

Background. Previous research on small‐group learning has found that level of constructive activity (solving or explaining how to solve problems using ideas stated or implied in the explanation provided by a partner) was a better predictor of post‐test achievement than either a student's prior achievement or the quality of help received (Webb, Troper, & Fall, 1995).

Aims. The purpose of this study was to extend this research by examining the influence of additional factors, in particular, achievement goals and comprehension monitoring, on low achieving students' constructive activity after receiving help from a high achieving peer.

Sample. Thirty‐two low achieving upper elementary students from an urban school district in the mid‐west of the United States were paired with high achieving partners.

Methods. Videotape data from a previously reported study on peer collaboration were transcribed and reanalyzed. In that study, dyads were randomly assigned instructions designed to induce either a learning or performance goal and were videotaped as they worked together to solve a set of mathematical word problems. The following day, students were individually post‐tested on problems similar to the ones worked on in pairs.

Results. Consistent with previous research, low achieving students' level of constructive activity predicted post‐test performance. In addition, constructive activity was found to mediate the relationship between achievement goals and learning. However, achievement goals were not related to low achievers constructive use of help. Instead, achievement goals were related to low achievers' relative accuracy in comprehension monitoring, which in turn was related to level of constructive activity.

Conclusions. The meaning of these results for understanding the processes by which low achievers learn from peer help and implications for classroom practice are discussed.
The association between job strain and emotional exhaustion in a cohort of 1,028 Finnish teachers
Authors: Santavirta Nina , Solovieva Svetlana , Theorell T öres
Published: September 2006

Background.Teachers' work overload has been the subject of intense research, and the results of these studies show that a substantial proportion of teachers perceive their job as very stressful.

Aims.To investigate how different formulations of high demands and low decision latitude was related to teachers' burnout, and to estimate the possible interaction between these factors.

Sample.The sample consisted of 1,028 school teachers.

Method.Multivariate covariant analyses (MANCOVA) was used to evaluate the relationship between a high‐strain job defined by 3 different cut‐off points and burnout. Logistical regression analysis was used to estimate the separate and joint effects of demand and decision authority on emotional exhaustion. Interaction between high demands and low decision authority was analysed using relative excess risk due to interaction (RERI). An attributable proportion (AP) was calculated in order to estimate the proportion of emotionally exhausted teachers among those exposed to both risk factors that was attributable to their synergistic interaction. The group of teachers who perceived their job as a low‐strain job was used as the reference group in the analysis.

Results.The effect of job strain on burnout was proved to be consistent and robust across alternative formulations. The main effect of high demands exceeded that of low decision authority in relation to emotional exhaustion. Furthermore, the 2 factors acted synergistically to increase the risk of burnout.

Conclusions.In the case of burnout, teachers who perceived their job as highly demanding and low in control, 69% of the effect could be attributed to the synergism of these 2 factors.
Self‐handicapping in school physical education: The influence of the motivational climate
Authors: Standage Martyn , Treasure Darren C. , Hooper Katherine , Kuczka Kendy
Published: September 2006

Background. Self‐handicapping is an attribution‐related process whereby individuals create performance impediments/excuses to protect self‐worth in socially evaluative environments. Thus, the prevailing motivational climate would appear to be an important factor when attempting to understand the situational self‐handicapping process within school physical education.

Aims. Drawing from achievement goal theory, the study examined the effect of experimentally induced conditions (viz. task vs. ego) on situational self‐handicapping.

Sample. Seventy British secondary school students (36 females and 34 males; M age = 11.98; SD=0.31).

Method. Participants were randomly assigned to partake in a running endurance task in either an ego‐involving (20 male students and 16 female students) or a task‐involving (14 male students and 20 female students) condition. Prior to completing the experimental task, participants were given the opportunity to claim situational self‐handicaps. Data for goal orientations, subjective climate perceptions, perceived ability and perceived task importance were also obtained.

Results. After determining the effectiveness of the experimental manipulation, results revealed participants in the ego‐involving condition to report significantly more situational self‐handicapping claims. Further, and after controlling for individual difference variables, the results of moderated hierarchical regression analysis revealed subjective perceptions of an ego‐involving climate to be the main positive predictor of situational self‐handicapping. Although a weaker contributor to the percentage of variance explained, task orientation emerged as a negative predictor of situational self‐handicapping.

Conclusions. The findings suggest that PE teachers would be prudent to minimize ego‐involving situations should they wish to reduce situational self‐handicapping.
Estimating standard errors in feature network models
Authors: Frank Laurence E. , Heiser Willem J.
Published: September 2006

Feature network models are graphical structures that represent proximity data in a discrete space while using the same formalism that is the basis of least squares methods employed in multidimensional scaling. Existing methods to derive a network model from empirical data only give the best‐fitting network and yield no standard errors for the parameter estimates. The additivity properties of networks make it possible to consider the model as a univariate (multiple) linear regression problem with positivity restrictions on the parameters. In the present study, both theoretical and empirical standard errors are obtained for the constrained regression parameters of a network model with known features. The performance of both types of standard error is evaluated using Monte Carlo techniques.
Mood‐management dynamics: The interrelationship between moods and behaviours
Authors: Hess James D. , Kacen Jacqueline J. , Kim Junyong
Published: September 2006

People actively attempt to create and maintain positive moods and to escape from negative moods by engaging in various activities. The principle of homeostasis explains the essence of the mood‐management system: adjustments of individuals' moods and activities help maintain constant their conditions of life. We model the dynamics of mood and mood‐management behaviour through a pair of interdependent, linear differential equations and estimate the equations using mood and behaviour data collected from an adult panel. Because empirically fitting continuous‐time differential equations to intermittent observations is uncommon in the literature, we show how to transform differential equations into equations that can be estimated using simultaneous‐equation regression methods. Our adult panel shows strong homeostasis in mood management with mood episodes of several hours and no evidence of endogenous mood cycles.
Bayesian adaptive estimation of arbitrary points on a psychometric function
Authors: García‐Pérez Miguel A. , Alcalá‐Quintana Rocío
Published: September 2006

Bayesian adaptive methods have been extensively used in psychophysics to estimate the point at which performance on a task attains arbitrary percentage levels, although the statistical properties of these estimators have never been assessed. We used simulation techniques to determine the small‐sample properties of Bayesian estimators of arbitrary performance points, specifically addressing the issues of bias and precision as a function of the target percentage level. The study covered three major types of psychophysical task (yes‐no detection, 2AFC discrimination and 2AFC detection) and explored the entire range of target performance levels allowed for by each task. Other factors included in the study were the form and parameters of the actual psychometric function Ψ, the form and parameters of the model functionMassumed in the Bayesian method, and the location of Ψ within the parameter space. Our results indicate that Bayesian adaptive methods render unbiased estimators of any arbitrary point on ψ only whenM=Ψ, and otherwise they yield bias whose magnitude can be considerable as the target level moves away from the midpoint of the range of Ψ. The standard error of the estimator also increases as the target level approaches extreme values whether or notM=Ψ. Contrary to widespread belief, neither the performance level at which bias is null nor that at which standard error is minimal can be predicted by the sweat factor. A closed‐form expression nevertheless gives a reasonable fit to data describing the dependence of standard error on number of trials and target level, which allows determination of the number of trials that must be administered to obtain estimates with prescribed precision.
Assessing change with the extended logistic model
Authors: Cristante Francesca , Robusto Egidio
Published: September 2006

The purpose of this article is to define a method for the assessment of change. A reinterpretation of the extended logistic model is proposed. The extended logistic model for the assessment of change (ELMAC) allows the definition of a time parameter which is supposed to identify whether change occurs during a period of time, given a specific event or phenomenon. The assessment of a trend of change through time, on the basis of the time parameter which is estimated at different successive occasions during a period of time, is also considered. In addition, a dispersion parameter is calculated which identifies whether change is consistent at each time point. The issue of independence is taken into account both in relation to the time parameter and the dispersion parameter. An application of the ELMAC in a learning process is presented. The interpretation of the model parameters and the model fit statistics is consistent with expectations.
Estimating confidence intervals for principal component loadings: A comparison between the bootstrap and asymptotic results
Authors: Timmerman Marieke E. , Kiers Henk A. L. , Smilde Age K.
Published: September 2006

Confidence intervals (CIs) in principal component analysis (PCA) can be based on asymptotic standard errors and on the bootstrap methodology. The present paper offers an overview of possible strategies for bootstrapping in PCA. A motivating example shows that CI estimates for the component loadings using different methods may diverge. We explain that this results from both differences in quality and in perspective on the rotational freedom of the population loadings. A comparative simulation study examines the quality of various estimated component loading CIs. The bootstrap approach is more flexible and generally yields better CIs than the asymptotic approach. However, in the case of a clear simple structure of varimax rotated loadings, one can be confident that the asymptotic estimates are reasonable as well.
Conditional mixed models with crossed random effects
Authors: Tibaldi Fabian S. , Verbeke Geert , Molenberghs Geert , Renard Didier , Van den Noortgate Wim , de Boeck Paul
Published: September 2006

The analysis of continuous hierarchical data such as repeated measures or data from meta‐analyses can be carried out by means of the linear mixed‐effects model. However, in some situations this model, in its standard form, does pose computational problems. For example, when dealing with crossed random‐effects models, the estimation of the variance components becomes a non‐trivial task if only one observation is available for each cross‐classified level. Pseudolikelihood ideas have been used in the context of binary data with standard generalized linear multilevel models. However, even in this case the problem of the estimation of the variance remains non‐trivial. In this paper, we first propose a method to fit a crossed random‐effects model with two levels and continuous outcomes, borrowing ideas from conditional linear mixed‐effects model theory. We also propose a crossed random‐effects model for binary data combining ideas of conditional logistic regression with pseudolikelihood estimation. We apply this method to a case study with data coming from the field of psychometrics and study a series of items (responses) crossed with participants. A simulation study assesses the operational characteristics of the method.
Reliability if deleted, not ‘alpha if deleted’: Evaluation of scale reliability following component deletion
Authors: Raykov Tenko
Published: September 2006

This paper demonstrates that the widely available and routinely used index ‘coefficient alpha if item deleted’ can be misleading in the process of construction and revision of multiple‐component instruments with congeneric measures. An alternative approach to evaluation of scale reliability following deletion of each component in a given composite is outlined that can be recommended in general for scale development purposes. The method provides ranges of plausible values for instrument reliability when dispensing with single components in a tentative composite, and permits testing hypotheses about reliability of resulting scale versions. The proposed procedure is illustrated with an example.
Anxiety‐induced performance catastrophes: Investigating effort required as an asymmetry factor
Authors: Hardy Lew , Beattie Stuart , Woodman Tim
Published: September 2006

Two studies are reported that test the hypothesis that previous support for the cusp catastrophe model of anxiety and performance, and the hysteresis effect in particular, could have been due to a complex interaction between cognitive anxiety and effort required rather than between cognitive anxiety and physiological arousal. We used task difficulty to manipulate effort required in a letter transformation task. Experiment 1 (N=32) used high levels of trait anxiety together with a competitive environment to induce state anxiety. Experiment 2 (N=20) used a competitive environment with social pressure and ego threat instructions to induce high levels of worry. Both studies revealed significant three‐way interactions as hypothesized with follow‐up tests showing some support for the hysteresis hypothesis in Study 1, and strong support for the hysteresis hypothesis in Study 2. The findings support a processing efficiency theory explanation of anxiety‐induced performance catastrophes and indicate that two cusp catastrophe models of performance may exist; one that incorporates the interactive effects of cognitive anxiety and physiological arousal upon performance and the other that incorporates the interactive effects of cognitive anxiety and effort required upon performance.
Using composite images to assess accuracy in personality attribution to faces
Authors: Little Anthony C. , Perrett David I.
Published: September 2006

Several studies have demonstrated some accuracy in personality attribution using only visual appearance. Using composite images of those scoring high and low on a particular trait, the current study shows that judges perform better than chance in guessing others' personality, particularly for the traits conscientiousness and extraversion. This study also shows that attractiveness, masculinity and age may all provide cues to assess personality accurately and that accuracy is affected by the sex of both of those judging and being judged. Individuals do perform better than chance at guessing another's personality from only facial information, providing some support for the popular belief that it is possible to assess accurately personality from faces.
Do people with autistic spectrum disorder show normal selection for attention? Evidence from change blindness
Authors: Fletcher‐Watson S. , Leekam S. R. , Turner M. A. , Moxon L.
Published: September 2006

People in the general population are typically very poor at detecting changes in pictures of complex scenes. The degree of this ‘change blindness’, however, varies with the content of the scene: when an object is semantically important or contextually inappropriate, people may be more effective at detecting changes. Two experiments investigated change blindness in people with autism, who are known from previous research to be efficient in detecting features yet poor at processing stimuli for meaning and context. The first experiment measured the effect of semantic information while the second investigated the role of context in directing attention. In each task, participants detected the dissimilarity between pairs of images. Both groups showed a main effect of image type in both experimental tasks, showing that their attention was directed to semantically meaningful and contextually inappropriate items. However, the autistic group also showed a greater difficulty detecting changes to semantically marginal items in the first experiment. Conclusions point to a normal selection of items for attention in people with autism spectrum disorders, although this may be combined with difficulty switching or disengaging attention.
Implicit and explicit control of motor actions: Revisiting some early evidence
Authors: Mullen Richard , Hardy Lew , Oldham Anthony
Published: September 2006

Two studies have questioned Masters' (1992) contention that skills acquired in implicit practice conditions are less likely to fail under pressure than those acquired explicitly. The studies produced conflicting results. The aim of the present study was to revisit the designs of both studies in an attempt to clarify the situation. Thirty‐two participants were allocated to one of three separate implicit training groups or an explicit training group, and practised putting golf balls. Participants were exposed to an anxiety intervention at two points during practice. Putting performance across practice and anxiety phases were analysed using the number of putts successfully completed as the main dependent variable. We found further evidence for the suggestion that motor skills are robust under pressure when acquired in implicit practice conditions.
Empathizing and systemizing: What are they, and what do they contribute to our understanding of psychological sex differences?
Authors: Nettle Daniel
Published: September 2006

Empathizing and systemizing have recently been put forward as two important individual‐difference dimensions, whose different mean levels in men and women are argued to account for many psychological sex differences. This paper presents a series of studies designed to investigate the reliability and validity of the empathizing and systemizing quotients (EQ & SQ), to relate them to existing personality constructs, and to replicate reported sex and sexual orientation‐related differences. Correlations with interests and social behaviour suggest the two measures are valid. However, empathizing appears essentially equivalent to agreeableness in the five‐factor model of personality. Systemizing cannot be reduced to established personality dimensions, though it is moderately correlated with conscientiousness and openness. Men have higher levels of systemizing than women, and non‐heterosexual women higher than heterosexuals. However, no differences were found between heterosexual and non‐heterosexual men. Although systemizing and empathizing account for a number of observed sex differences, there are others they do not explain.
Sex differences in the effects of interest on boys' and girls' reading comprehension
Authors: Oakhill Jane V. , Petrides Alison
Published: September 2006

This study compared the reading comprehension of groups of boys and girls (aged 10–11) on two tests, one of which was about the evacuation of children during the Second World War and the other of which was about spiders. These were the actual year 6 SATS reading tests administered in the UK in 1998 and 1999. The majority of the boys said that they would prefer to read the text about spiders, and the majority of the girls said they would prefer to read the text about leaving home in wartime. These patterns of preference were reflected in the children's performance on the actual tests. However, whereas the boys' comprehension was significantly affected by the content of the tests (they showed better performance on the test about spiders) the girls' performance was relatively little influenced by the content of the test. The implications of these results for testing reading, and for encouraging reading more generally, are discussed.
Characterizing linguistic structure with mutual information
Authors: Pothos Emmanuel M. , Juola Patrick
Published: September 2006

We explore mutual information (MI) as a means of characterizing linguistic statistical structure. The MI between two linguistic tokensxandyis the degree to which seeingxhelps us anticipate the occurrence ofy. We computed MI between words in 595 samples of written text in 25 languages. Our analyses indicate that MI dependencies do not extend beyond a range of five words. Moreover, the similarity between MI profiles of different languages was used to cluster the languages. These results are discussed in terms of a putative link between short‐term memory and linguistic structure and the further utility of MI in terms of characterizing the latter.
Kinship and altruism: A cross‐cultural experimental study
Authors: Madsen Elainie A. , Tunney Richard J. , Fieldman George , Plotkin Henry C. , Dunbar Robin I. M. , Richardson Jean‐Marie , McFarland David
Published: September 2006

Humans are characterized by an unusual level of prosociality. Despite this, considerable indirect evidence suggests that biological kinship plays an important role in altruistic behaviour. All previous reports of the influence of kin selection on human altruism have, however, used correlational (rather than experimental) designs, or imposed only a hypothetical or negligible time cost on participants. Since these research designs fail either to control for confounding variables or to meet the criteria required as a test of Hamilton's rule for kin selection (that the altruist pays a true cost), they fail to establish unequivocally whether kin selection plays a role. We show that individuals from two different cultures behave in accordance with Hamilton's rule by acting more altruistically (imposing a higher physical cost upon themselves) towards more closely related individuals. Three possible sources of confound were ruled out: generational effects, sexual attraction and reciprocity. Performance on the task however did not exhibit a perfect linear relationship with relatedness, which might reflect either the intrusion of other variables (e.g. cultural differences in the way kinship is costed) or that our behavioural measure is insufficiently sensitive to fine‐tuned differences in the way individuals view their social world. These findings provide the first unequivocal experimental evidence that kinship plays a role in moderating altruistic behaviour. Kinship thus represents a baseline against which individuals pitch other criteria (including reciprocity, prosociality, obligation and a moral sense) when deciding how to behave towards others.
The role of effort in influencing the effect of anxiety on performance: Testing the conflicting predictions of processing efficiency theory and the conscious processing hypothesis
Authors: Wilson Mark , Smith Nickolas C. , Holmes Paul S.
Published: September 2006

The aim of this study was to test the conflicting predictions of processing efficiency theory (PET) and the conscious processing hypothesis (CPH) regarding effort's role in influencing the effects of anxiety on a golf putting task. Mid‐handicap golfers made a series of putts to target holes under two counterbalanced conditions designed to manipulate the level of anxiety experienced. The effort exerted on each putting task was assessed though self‐report, psychophysiological (heart rate variability) and behavioural (pre‐putt time and glances at the target) measures. Performance was assessed by putting error. Results were generally more supportive of the predictions of PET rather than the CPH as performance was maintained for some performers despite increased state anxiety and a reduction in processing efficiency. The findings of this study support previous research suggesting that both theories offer useful theoretical frameworks for examining the relationship between anxiety and performance in sport.
Application of the theory of planned behaviour to the prediction of objectively assessed breaking of posted speed limits
Authors: Conner Mark , Lawton Rebecca , Parker Dianne , Chorlton Kathryn , Manstead Antony S.R. , Stradling Stephen
Published: September 2006

In two studies the Theory of Planned Behaviour (TPB) including moral norms, anticipated regret and past behaviour was applied to predicting intention to exceed the posted speed limit across different roads and objectively assessed speeding behaviour. All measures except behaviour were taken by self‐report questionnaires referring to different driving scenarios. The behaviour measures were based on performance in a simulator (Study 1) or unobtrusive on‐road speed camera assessment taken without driver awareness (Study 2) across roads with varying posted speed limits. Results are reported averaged across road types in both studies. In Study 1 (N = 83), 82% of the variance in intentions to speed was explained, with attitudes, subjective norms, perceived behavioural control (PBC), moral norms, anticipated regret and past behaviour being significant predictors. A total of 35% of the variance in speed as assessed on a driving simulator was accounted for with intentions, PBC, moral norms and previous accidents being significant predictors. In Study 2 (N = 303), 76% of the variance in intentions to speed was explained with attitudes, moral norms, anticipated regret and past behaviour being significant predictors. A total of 17% of the variance in speed as assessed on‐road was accounted for with intentions and moral norms being significant. Practical implications of the findings for road safety are discussed.