Cultural determinants of the gap between self-estimated navigation ability and wayfinding performance: evidence from 46 countries

Cognitive abilities can vary widely. Some people excel in certain skills, others struggle. However, not all those who describe themselves as gifted are. One possible influence on self-estimates is the surrounding culture. Some cultures may amplify self-assurance and others cultivate humility. Past research has shown that people in different countries can be grouped into a set of consistent cultural clusters with similar values and tendencies, such as attitudes to masculinity or individualism. Here we explored whether such cultural dimensions might relate to the extent to which populations in 46 countries overestimate or underestimate their cognitive abilities in the domain of spatial navigation. Using the Sea Hero Quest navigation test and a large sample (N = 383,187) we found cultural clusters of countries tend to be similar in how they self-rate ability relative to their actual performance. Across the world population sampled, higher self-ratings were associated with better performance. However, at the national level, higher self-ratings as a nation were not associated with better performance as a nation. Germanic and Near East countries were found to be most overconfident in their abilities and Nordic countries to be most under-confident in their abilities. Gender stereotypes may play a role in mediating this pattern, with larger national positive attitudes to male stereotyped roles (Hofstede's masculinity dimension) associated with a greater overconfidence in performance at the national level. We also replicate, with higher precision than prior studies, evidence that older men tend to overestimate their navigation skill more than other groups. These findings give insight into how culture and demographics may impact self-estimates of our abilities.

Inter-annual and spatial climatic variability have led to a balance between local fluctuating selection and wide-range directional selection in a perennial grass species

BACKGROUND AND AIMS

The persistence of a plant population under a specific local climatic regime requires phenotypic adaptation with underlying particular combinations of alleles at adaptive loci. The level of allele diversity at adaptive loci within a natural plant population conditions its potential to evolve, notably towards adaptation to a change in climate. Investigating the environmental factors that contribute to the maintenance of adaptive diversity in populations is thus worthwhile. Within-population allele diversity at adaptive loci can be partly driven by the mean climate at the population site but also by its temporal variability.

METHODS

The effects of climate temporal mean and variability on within-population allele diversity at putatively adaptive quantitative trait loci (QTLs) were evaluated using 385 natural populations of Lolium perenne (perennial ryegrass) collected right across Europe. For seven adaptive traits related to reproductive phenology and vegetative potential growth seasonality, the average within-population allele diversity at major QTLs (HeA) was computed.

KEY RESULTS

Significant relationships were found between HeA of these traits and the temporal mean and variability of the local climate. These relationships were consistent with functional ecology theory.

CONCLUSIONS

Results indicated that temporal variability of local climate has likely led to fluctuating directional selection, which has contributed to the maintenance of allele diversity at adaptive loci and thus potential for further adaptation.

Integrating a newly developed BAC-based physical mapping resource for Lolium perenne with a genome-wide association study across a L. perenne European ecotype collection identifies genomic contexts associated with agriculturally important traits

BACKGROUND AND AIMS

Lolium perenne (perennial ryegrass) is the most widely cultivated forage and amenity grass species in temperate areas worldwide and there is a need to understand the genetic architectures of key agricultural traits and crop characteristics that deliver wider environmental services. Our aim was to identify genomic regions associated with agriculturally important traits by integrating a bacterial artificial chromosome (BAC)-based physical map with a genome-wide association study (GWAS).

METHODS

BAC-based physical maps for L. perenne were constructed from ~212 000 high-information-content fingerprints using Fingerprint Contig and Linear Topology Contig software. BAC clones were associated with both BAC-end sequences and a partial minimum tiling path sequence. A panel of 716 L. perenne diploid genotypes from 90 European accessions was assessed in the field over 2 years, and genotyped using a Lolium Infinium SNP array. The GWAS was carried out using a linear mixed model implemented in TASSEL, and extended genomic regions associated with significant markers were identified through integration with the physical map.

KEY RESULTS

Between ~3600 and 7500 physical map contigs were derived, depending on the software and probability thresholds used, and integrated with ~35 k sequenced BAC clones to develop a resource predicted to span the majority of the L. perenne genome. From the GWAS, eight different loci were significantly associated with heading date, plant width, plant biomass and water-soluble carbohydrate accumulation, seven of which could be associated with physical map contigs. This allowed the identification of a number of candidate genes.

CONCLUSIONS

Combining the physical mapping resource with the GWAS has allowed us to extend the search for candidate genes across larger regions of the L. perenne genome and identified a number of interesting gene model annotations. These physical maps will aid in validating future sequence-based assemblies of the L. perenne genome.

Fancy a cup of scald? - The role of hot beverage burns in paediatric burns admissions in Ireland

Burns and scalds are preventable injuries in children that typically occur in the home. This study aimed to examine the role of hot beverage scalds in paediatric burn admissions in order to identify key target audiences for future safety strategies. Using the Hospital Inpatient Enquiry System (HIPE) a retrospective study of paediatric burn admissions in 2014 examined demographics, cause and severity of injury and location of occurrence. There were 233 paediatric discharges (age 0-18 yrs.) with a principal diagnosis of burn injury; 57% of these occurred in children under three years and 95% of these occurred in the home. Scalds caused 74% of burn injuries; hot beverages accounted for least 33% of these of which 77% were partial thickness and 73% were upper body burns. Effective hot beverage scald prevention strategies, targeted towards caregivers in the home, are required.

Germplasm dynamics: the role of ecotypic diversity in shaping the patterns of genetic variation in Lolium perenne

Perennial ryegrass (Lolium perenne) is the most widely grown temperate grass species globally. Intensive plant breeding in ryegrass compared to many other crops species is a relatively recent exercise (last 100 years) and provides an interesting experimental system to trace the extent, impact and trajectory of undomesticated ecotypic variation represented in modern ryegrass cultivars. To explore germplasm dynamics in Lolium perenne, 2199 SNPs were genotyped in 716 ecotypes sampled from 90 European locations together with 249 cultivars representing 33 forage/amenity accessions. In addition three pseudo-cross mapping populations (450 individual recombinants) were genotyped to create a consensus genetic linkage map. Multivariate analyses revealed strong differentiation between cultivars with a small proportion of the ecotypic variation captured in improved cultivars. Ryegrass cultivars generated as part of a recurrent selection programme (RSP) are strongly associated with a small number of geographically localised Italian ecotypes which were among the founders of the RSP. Changes in haplotype frequency revealed signatures of selection in genes putatively involved in water-soluble carbohydrate (WSC) accumulation (a trait selected in the RSP). Retrospective analysis of germplasm in breeding programmes (germplasm dynamics) provides an experimental framework for the identification of candidate genes for novel traits such as WSC accumulation in ryegrass.

Genetic-geographic correlation revealed across a broad European ecotypic sample of perennial ryegrass (Lolium perenne) using array-based SNP genotyping

Publically available SNP array increases the marker density for genotyping of forage crop, Lolium perenne. Applied to 90 European ecotypes composed of 716 individuals identifies a significant genetic-geographic correlation. Grassland ecosystems are ubiquitous across temperate and tropical regions, totalling 37% of the terrestrial land cover of the planet, and thus represent a global resource for understanding local adaptations to environment. However, genomic resources for grass species (outside cereals) are relatively poor. The advent of next-generation DNA sequencing and high-density SNP genotyping platforms enables the development of dense marker assays for population genetics analyses and genome-wide association studies. A high-density SNP marker resource (Illumina Infinium assay) for perennial ryegrass (Lolium perenne) was created and validated in a broad ecotype collection of 716 individuals sampled from 90 sites across Europe. Genetic diversity within and between populations was assessed. A strong correlation of geographic origin to genetic structure was found using principal component analysis, with significant correlation to longitude and latitude (P < 0.001). The potential of this array as a resource for studies of germplasm diversity and identifying traits underpinning adaptive variation is highlighted.

Difficult airway equipment: a survey of standards across metropolitan Perth

The importance of appropriate equipment to manage the difficult airway has been highlighted by the publication of the Australian and New Zealand College of Anaesthetists (ANZCA) guidelines in 2012. We set out to audit compliance with these guidelines in all public and private sites providing general anaesthesia in metropolitan Perth. Public and private health care websites identified 39 sites of which 37 were studied. Institutional and ethics approval was obtained. A tick-box design audit tool, based on the ANZCA guidelines, was used to collect information regarding the dedicated difficult airway container (DDAC) at each site. As recommended in the guidelines, only equipment within the DDAC was considered. Further data about each site, including the number of theatre suites, satellite anaesthetic areas, use of capnography and categories of patients treated (adult, obstetric and paediatric) were collected. An adult DDAC was found at 92% of all sites, but none of the sites had all the essential equipment listed in the ANZCA guidelines. There was limited provision of adult difficult airway equipment within private sites compared to public, and less provision of paediatric difficult airway equipment across all sites treating paediatric patients in metropolitan Perth. Capnography was available in 76% of post anaesthesia care units and used regularly in 27%. Adherence to the ANZCA guidelines regarding the DDAC could be improved. Standardised equipment across a metropolitan region would be of value in the management of the difficult airway.

Monitoring temperature in children undergoing anaesthesia: a comparison of methods

Children undergoing anaesthesia are prone to hypothermia. Perioperative monitoring of patient temperature is, therefore, standard practice. Postoperative temperature is regarded as a key anaesthetic performance indicator in Australian hospitals. Many different methods and sites of temperature measurement are used perioperatively. It is unclear to what degree these methods might be interchangeable. The aim of this study was to determine the relationships between temperatures measured at different sites in anaesthetised children. Two hundred children, 0 to 17 years, undergoing general anaesthesia for elective non-cardiac surgery, were prospectively recruited. Temperature measurements were taken in the operating theatre concurrently at the nasopharynx, tympanic membranes, temporal artery, axilla and skin (chest). Patient age and weight were documented. Temperatures varied according to site of measurement. The mean difference from nasopharyngeal temperature to temperatures at left and right tympanic, temporal, axillary and cutaneous sites were +0.24°C, +0.24°C, +0.35°C, -0.38°C and -1.70°C, respectively. Levels of agreement to nasopharyngeal temperature were similar at tympanic, temporal and axillary sites. Tympanic and temporal temperatures were superior to axillary temperatures for detection of mild hypothermia (<36°C). Skin temperature showed a large variation from nasopharyngeal measurements. Our findings indicate that measured temperatures vary between sites. Understanding these variations is important for interpreting temperature readings.

Lessons from natural and artificial polyploids in higher plants

Polyploidy in higher plants is a major source of genetic novelty upon which selection may act to drive evolution, as evidenced by the widespread success of polyploid species in the wild. However, research into the effects of polyploidy can be confounded by the entanglement of several processes: genome duplication, hybridisation (allopolyploidy is frequent in plants) and subsequent evolution. The discovery of the chemical agent colchicine, which can be used to produce artificial polyploids on demand, has enabled scientists to unravel these threads and understand the complex genomic changes involved in each. We present here an overview of lessons learnt from studies of natural and artificial polyploids, and from comparisons between the 2, covering basic cellular and metabolic consequences through to alterations in epigenetic gene regulation, together with 2 in-depth case studies in Senecio and Glycine. See also the sister article focusing on animals by Arai and Fujimoto in this themed issue.

The National Newborn Bloodspot Screening Programme (NNBSP) process review 2010

The National Newborn Bloodspot Screening Programme (NNBSP) incorporates screening for several conditions where early identification helps prevent serious disability or mortality. A national group was established (2009) to plan for the inclusion of screening for cystic fibrosis (CF); as part of this process a review of the existing NNBSP was undertaken. Information was obtained through consultation with the Director of the National Newborn Bloodspot Screening Laboratory (NNBSL) and survey of maternity units (20), Local Health Office (LHO) areas (32), and practicing domiciliary midwives (16). Response rate: hospitals 100%; LHO areas 100%; domiciliary midwives 56%. Potential for strengthening quality assurance was identified e.g. single comprehensive screening register, consistent and timely procedures for checking results. Recommendations, many of which have since been implemented, included overall governance structure, liaison officer, quality assurance programme, ring-fenced funding, standardised unique identifier, dedicated laboratory IT system, secure web-based transmission of results and fail-safe method of tracking samples.

Potential organ donor audit in Ireland

As increasing demand for organs is a challenge for transplant services worldwide it is essential to audit the process of organ donation. To address this, a national audit of potential organ donors was undertaken across hospitals with Intensive Care Units (N = 36). Questionnaires were returned on all patients (n = 2073) who died in these units from 1/9/07-31/8/08; 200 (10%) of these patients were considered for Brain Stem Testing (BST), 158 patients (79%) were diagnosed Brain Stem Dead (BSD) and 138 patients (87%) became potential donors. Consent for donation was given by 92 (69%) next of kin and 90 potential donors (65%) became organ donors. There was no evidence of a large number of potential organ donors being missed. Recommendations included completion of BSTs on all appropriate patients, development of support on BST, referral of all BSD patients to the Organ Procurement Service; enhanced co-ordination within hospitals and sustained information/education campaigns.

Order out of chaos in the hybrid plant nucleus

The plant nucleus is a highly ordered and dynamic structure, with a considerable level of variation between species in terms of genome size, genome organisation, chromosome territories and patterns associated with developmental changes. Diploids naturally represent the simplest state of affairs, but in the plant world more than 70% of species may have been involved in polyploidisation events at some stage during their evolution. Autopolyploids have multiple sets of chromosomes from a single species, and aside from the complexities of meiosis we may expect them to accommodate their polysomic state as well as their disomic relatives. Allopolyploids are at the other extreme, with multiple sets of chromosomes from 2 or more species, embedded in the cytoplasm of the maternal parent following hybridisation, and this presents the nucleus of nascent allopolyploids with certain zones of conflict. Nature has found ways to make the accommodation, and recent developments in molecular analysis have now opened a window for the experimenter to view the process of this adjustment, and to see how rapidly it takes place and what processes are involved. The nature of the resolution of nuclear conflicts in diploid hybrids and in allopolyploids is discussed.

Quality of life in young people with cystic fibrosis: effects of hospitalization, age and gender, and differences in parent/child perceptions

BACKGROUND

The Cystic Fibrosis Questionnaire-Revised version (CFQ-R) was used to evaluate age/gender effects on quality of life (QOL) in Australian young people with cystic fibrosis (CF) who were inpatients/outpatients aged 6-18 years. Parent/child agreement was also examined.

METHOD

The CFQ-R was completed by 18 outpatients, and 15 inpatients at admission for an acute pulmonary exacerbation to a tertiary hospital, Brisbane, Australia, as well as by parents of those aged 6-13 years.

RESULTS

Inpatients scored significantly lower than outpatients for the CFQ-R domains 'emotional state', 'social', 'body image' and 'respiratory symptoms'. Young people aged 6-13 years scored significantly better than those aged 14-18 years for 'emotional state', 'body image' and 'treatment burden'. Women perceived less 'treatment burden' than did men. Young people aged 6-13 years perceived less 'treatment burden' than did their parents. A significant interaction occurred between child/parent report and gender for 'emotional state' and 'eating disturbances'.

CONCLUSION

The CFQ-R found differences between inpatients and outpatients and between younger and older paediatric patients with CF, and between parent and child perceptions of QOL.

Integration, Coordination and Multidisciplinary Care: What can These Approaches Offer to Australian Primary Health Care?

Australia's population is ageing and the consequential burden of chronic disease increasingly challenges the health system. This has raised interest in, and awareness of, approaches built on multidisciplinary teams and integrated and coordinated care in managing the complex care needs of patient groups such as the chronically ill or frail aged. A systematic investigation of the literature relating to these approaches provided the opportunity to explore the meaning of these terms and their potential application and relevance to the Australian primary health care setting. Five systematic reviews of a sentinel condition and an exemplar approach to coordinated and multidisciplinary care were completed. Common learnings from the individual reviews were identified. The literature suggests that approaches encouraging a coordinated and multidisciplinary plan of care for individual patients and/or particular populations may improve a variety of outcomes. There are many methodological considerations in conducting reviews of complex interventions and in assessing their applicability to the Australian health system.

Evaluation of a community fissure sealant programme in County Meath, Ireland

OBJECTIVE

To evaluate the fissure sealant programme operated by the North Eastern Health Board Dental Service in County Meath, Republic of Ireland. The fissure sealant programme forms part of the school dental service aimed at children in first class (age group 6-7 years).

DESIGN

Cross sectional study with retrospective analysis of dental records.

CLINICAL SETTING

Schools in County Meath in 1999.

PARTICIPANTS

Children in fourth class (mean age 9.6 years) in the school year 1999/2000 who had participated in the fissure sealant programme in the school year 1996/97.

MAIN OUTCOME MEASURES

Sealant retention using the criteria of Simonsen.

RESULTS

The mean age of sealant was 2.3 years. Fifty six percent of sealants were completely retained, 27% were partially retained and 12.8% were missing. The majority (73%) of children had some sealant on at least one tooth. Caries experience in previously sealed teeth was low (2.9%). Children who had all four first permanent molars sealed had a significantly lower DMFT (visual) than those who had no sealants (Wilcoxan p < 0.0001).

CONCLUSION

Despite lack of maintenance of sealants in this study, retention rates compared favourably with similar international studies and caries experience in previously sealed teeth was low. The use of a written sealant policy and protocol for sealant application and equipment maintenance could further improve retention rates. Children who had no sealants had significantly poorer dental health than children who had all four first permanent molars sealed.

Impetus beliefs as default heuristics: dissociation between explicit and implicit knowledge about motion

We examined the extent to which findings from the literature on naive physics and representational momentum studies are consistent with impetus beliefs postulating imparted internal energy as a source of motion. In a literature review, we showed that, for situations in which impetus theory and physical principles make different predictions, representational momentum effects are consistent with impetus beliefs. In three new experiments, we examined people's implicit and explicit knowledge of the effect of mass on the rate of ascending motion. The results suggest that implicit knowledge is consistent with impetus theory and is unaffected by explicit knowledge. Expert physicists, whose explicit knowledge is in accord with Newtonian principles, exhibited the same implicit impetus beliefs as novices when asked to respond in a representational momentum paradigm. We propose that, in situations in which an immediate response is required and one does not have specific contextual knowledge about an object's motion, both physics experts and novices apply impetus principles as a default heuristic.

A dissociation between object manipulation spatial ability and spatial orientation ability

We developed psychometric tests of spatial orientation ability, in which people are shown a two-dimensional array of objects, imagine taking a perspective within the array, and indicate the direction to a target object from this perspective. Patterns of errors on these tests were consistent with experimental studies of perspective taking. Characteristic errors and verbal protocols supported the validity of the perspective-taking tests, suggesting that people encoded the objects in the display with respect to a body-centered coordinate system when the imagined perspective was more than 90 degrees different from the orientation of the display. By comparing alternative models in a confirmatory factor analysis, we found that the ability to mentally rotate and manipulate an imagined object (as measured by tests of spatial visualization and spatial relations) and the ability to reorient the imagined self (as measured by the perspective-taking tests) are separable spatial abilities.

Identification of transposon-tagged genes by the random sequencing of Mutator-tagged DNA fragments from Zea mays

We have used a universal adaptor amplification procedure to isolate random Mutator-tagged fragments from Mutator-active maize plants. Direct sequence characterization of 761 Mutator-tagged fragments indicated that a significant number were homologous to sequences within the public databases. The ability of Mutator-tagged fragments to detect homology was not related to the length of the sequence within the range 100-400 bp. However, fragments above this size did show an increased chance of detecting homology to either expressed sequence tags or genes. Characterization of the insertion sites of the Mutator elements suggested that while it does target transcribed regions, Mutator does not appear to have any site preference within the transcription unit. Hybridization of previously unidentified Mutator-tagged fragments to arrayed cDNA libraries confirmed that many of these also showed homology to transcribed regions of the genome. Examination of back-crossed progeny confirmed that all the insertions examined were germinal; however, in all but one case, selfing five individual Mutator-tagged lines failed to reveal an obvious phenotype. This study suggests that the random sequencing of Mutator-tagged fragments is capable of producing both a significant number of interesting transposon tagged genes and mutant plant lines, all of which could be extremely valuable in future gene discovery and functional genomics programmes.

Constraints on using the dual-task methodology to specify the degree of central executive involvement in cognitive tasks

The dual-task paradigm has been used to examine the role of the central executive in various cognitive tasks. In these studies, performance decrements in primary cognitive tasks performed concurrently with secondary executive tasks have been interpreted as evidence for the involvement of the central executive in those primary tasks. In the present study, we examined the effects of different secondary tasks on performance of three psychometric visuospatial tasks. The decrement in performance of these tasks when they were paired with secondary executive tasks was smallest for the psychometric task considered to most heavily involve the central executive and largest for the task considered least demanding of executive mechanisms. We propose that, when applied to the assessment of central executive involvement, the prevalent simple dual-task logic does not always apply. Special conditions that limit the application of the dual-task methodology include two inherently related factors--a response selection bottleneck and a strategic tradeoff between primary and secondary tasks.

A comparison of methods for estimating directions in egocentric space

A central issue for researchers of human spatial knowledge, whether focused on perceptually guided action or cognitive-map acquisition, is knowledge of egocentric directions, directions from the body to objects and places. Several methods exist for measuring this knowledge. We compared two particularly important methods, manual pointing with a dial and whole-body rotation (body heading), under various conditions of sensory or memory access to targets. In two experiments, blindfolded body rotation resulted in the greatest variability of performance (variable error), while the manual dial resulted in greater consistent bias (constant error). The variability of performance with body rotation was no greater than that of the dial when subjects' memory loads for directions to targets was reduced by allowing them to peek at targets in between trials, point to concurrent auditory targets, or point with their eyes open. In both experiments, errors with the manual dial were greater for directions to targets that were further from the closest orthogonal axis (ahead, behind, right, left), while errors with body rotation with restricted perceptual access were greater for directions to targets that were further from an axis straight ahead of subjects. This suggests that the two methods will produce evidence of different organizational frameworks for egocentric spatial knowledge. Implications for the structures and processes that underlie egocentric spatial knowledge, and are involved in estimating directions, are discussed, as is the value of decomposing absolute errors into variable and constant errors.

Spatial knowledge acquisition from maps and from navigation in real and virtual environments

In this study, the nature of the spatial representations of an environment acquired from maps, navigation, and virtual environments (VEs) was assessed. Participants first learned the layout of a simple desktop VE and then were tested in that environment. Then, participants learned two floors of a complex building in one of three learning conditions: from a map, from direct experience, or by traversing through a virtual rendition of the building. VE learners showed the poorest learning of the complex environment overall, and the results suggest that VE learners are particularly susceptible to disorientation after rotation. However, all the conditions showed similar levels of performance in learning the layout of landmarks on a single floor. Consistent with previous research, an alignment effect was present for map learners, suggesting that they had formed an orientation-specific representation of the environment. VE learners also showed a preferred orientation, as defined by their initial orientation when learning the environment. Learning the initial simple VE was highly predictive of learning a real environment, suggesting that similar cognitive mechanisms are involved in the two learning situations.

Is lower incisor extraction treatment a compromise?

In this paper orthodontic treatment involving extraction of a lower incisor is described. This has traditionally been regarded as a compromise as loss of a lower incisor renders it impossible to achieve true ideal occlusion. However, with careful case selection, treatment planning and visualization of the post-treatment occlusion, excellent functional and aesthetic results can be achieved. The various factors that govern the decision to treat certain malocclusions in this way are discussed and a clinical case is presented to demonstrate this type of treatment.

Mental animation in the visuospatial sketchpad: evidence from dual-task studies

We used the dual-task paradigm to provide evidence that inferring the motion of a component of a mechanical system (mental animation) is a spatial visualization process. In two experiments, participants were asked to solve mental animation problems while simultaneously retaining either a visuospatial working memory load (a configuration of dots in a grid) or a verbal memory load (a list of letters). Both experiments showed that mental animation interferes more with memory for a concurrent visuospatial load than with memory for a verbal load. Experiment 1 also showed that a visuospatial working memory load interferes more with mental animation than does a verbal memory load. Furthermore, Experiment 2 showed that mental animation interferes more with a visuospatial memory load than does a verbal reasoning task that takes approximately the same amount of time.

Properties of cognitive maps constructed from texts

Subjects in three experiments read texts describing the locations of landmarks in a fictitious town. Later they drew sketch maps and verified sentences describing the relative locations of the landmarks. We predicted that subjects would develop mental models of the town that were organized around important landmarks ("anchors"), as are cognitive maps constructed through real-world navigation. More specifically, we expected that landmarks used in the text as reference points for describing the locations of some other landmarks would emerge as anchors in the subjects' cognitive maps and would consequently be recalled more accurately. Results showed that subjects represented such reference-point landmarks more accurately than they did the locations of other landmarks. This effect was independent of: (1) the perspective from which the text was written (route or survey); (2) whether or not a map was present at learning; (3) the order of information in the text (linear or anchors-first), and (4) the amount of information available to the subjects while drawing sketch maps (the full text, the landmark names only, or no information).

Individual differences in mental animation during mechanical reasoning

In three experiments we tested the effects of spatial visualization ability on performance of a motion-verification task, in which subjects were shown a diagram of a mechanical system and were asked to verify a sentence stating the motion of one of the system components. We propose that this task involves component processes of (1) sentence comprehension, (2) diagram comprehension, (3) text-diagram integration, and (4) mental animation. Subjects with low spatial ability made more errors than did subjects with high spatial ability on this task, and they made more errors on items in which more system components had to be animated to solve the problem. In contrast, the high-spatial subjects were relatively accurate on all trials. These results indicate that spatial visualization is correlated with accuracy on the motion-verification task and suggest that this correlation is primarily due to the mental animation component of the task. Reaction time and eye-fixation data revealed no differences in how the high- and low-spatial subjects decomposed the task. The data of the two groups of subjects were equally consistent with a piecemeal model of mental animation, in which components are animated one by one in order of the causal chain of events in the system.

Mental animation: inferring motion from static displays of mechanical systems

Reaction-time and eye-fixation data are analyzed to investigate how people infer the kinematics of simple mechanical systems (pulley systems) from diagrams showing their static configuration. It is proposed that this mental animation process involves decomposing the representation of a pulley system into smaller units corresponding to the machine components and animating these components in a sequence corresponding to the causal sequence of events in the machine's operation. Although it is possible for people to make inferences against the chain of causality in the machine, these inferences are more difficult, and people have a preference for inferences in the direction of causality. The mental animation process reflects both capacity limitations and limitations of mechanical knowledge.

Mental animation: Inferring motion from static displays of mechanical systems

Reaction-time and eye-fixation data are analyzed to investigate how people infer the kinematics of simple mechanical systems (pulley systems) from diagrams showing their static configuration. It is proposed that this mental animation process involves decomposing the representation of a pulley system into smaller units corresponding to the machine components and animating these components in a sequence corresponding to the causal sequence of events in the machine's operation. Although it is possible for people to make inferences against the chain of causality in the machine, these inferences are more difficult, and people have a preference for inferences in the direction of causality. The mental animation process reflects both capacity limitations and limitations of mechanical knowledge.

Effect of sodium azide on hydrogen peroxide production by zymosan-activated human neutrophils

Stimulated neutrophils (PMNs) produce large quantities of superoxide anion, which is the precursor for hydrogen peroxide (H2O2). We developed a new fluorimetric assay to measure the H2O2 released by zymosan A-activated PMNs utilizing the oxidation of p-hydroxyphenylacetic acid by H2O2 to its fluorescent dimer in the presence of horseradish peroxidase. Zymosan-activated PMNs isolated from nine healthy volunteers and 20 patients with acute hypoxemic respiratory failure (AHRF) released after 90 min 2.3 +/- 0.3 and 2.4 +/- 1.3 nmol H2O2/10(6) PMNs, respectively. Inhibition of the heme enzymes by 1.0 mM sodium azide (NaN3) increased the H2O2 production to 21.6 +/- 4.4 nmol H2O2/10(6) PMNs in the control group (P less than 0.001), and to 22.5 +/- 14.7 nmol H2O2/10(6) PMNs in patients with AHRF (P less than 0.001). Incubation temperature, room temperature or 37 degrees C, did not change the total amount of H2O2 produced after 90 min by zymosan-activated PMN. Addition of NaN3 improved both the sensitivity and reproducibility of the measurement of H2O2 and allowed detection of H2O2 released by PMNs with coefficients of variation of less than 5% at PMN concentrations as low as 0.1 x 10(6) cells/ml. The amount of H2O2 released by activated PMNs did not distinguish healthy controls from patients with AHRF.

Typhoid perforation of the ileum: A therapeutic dilemma

Thirty-eight cases of typhoid perforation of the terminal ileum were encountered during a three-year period. Fourteen cases were treated conservatively, with a mortality of 36%. During the same period, the surgical mortality improved from 50% in 1972 to 11% in 1974. It is recommended that typhoid perforation be treated by operation.