Spontaneous and reflexive eye activity measures of mental workload

Measures of eye activity, such as blink rate and scanning patterns, have been used extensively as psychophysiological indices of mental workload. In a review of measures derived from spontaneous eye activity it is shown that different measures are differentially sensitive to specific aspects of mental workload. A less well-known measure of non-spontaneous eye activity, the blink reflex, is also reviewed. Experiments using discrete punctuate stimuli and continuous tasks analogous to real-world systems show that blink reflexes are modulated by attention and that this modulation reflects modality-specific attentional engagement. Future research should examine the utility of the blink reflex according to the desirable properties of sensitivity, diagnosticity, validity, reliability, ease of use, unobtrusiveness, and operator acceptance.

Prediction of coal ash fusion temperatures with the F*A*C*T thermodynamic computer package

This paper outlines research on the processes taking place within the coal mineral matter at high temperatures and development of the relationship between ash fusion temperatures (AFT) and phase equilibria of the coal ash slags. A new thermodynamic database for the Al-Ca-Fe-O-Si system developed by the author was used in conjunction with the thermodynamic computer package F*A*C*T for these purposes. In addition, high temperature experimental studies were undertaken that involved heat treatment and quenching of the ash cones followed by the analyses using different techniques. The study provided new information on the processes taking place during AFT test and demonstrated the validity of the AFTs predictions with F*A*C*T. Examples of practical applications of the AFT prediction method are given in the paper. The results of this study are important not only for the AFT predictions, but also in general for the application of phase equilibrium science to the characterisation of the coal mineral matter interactions at high temperature. (C) 2002 Elsevier Science Ltd. All rights reserved.

Evaluating two morningness scales with item response theory

Using a student sample (n = 692) and an organization sample (n = 180), we scrutinized two morning-evening orientation scales using item response theory (IRT) methods. We used IRT to compare the measurement precision of the Composite Scale (CS) and the Early/Late Preferences Scale (PS). The CS had slightly higher measurement precision at all ranges of orientations, except for extreme morning and evening orientations for which the PS had slightly higher precision. IRT item-level statistics were also computed to try to understand how morning-orientation items functioned. Items that asked questions about morning activities tended to be more discriminating indicators of morning-orientation than items that asked about evening or peak performance activities. Items that involved unpleasant activities were less frequently endorsed than items that involved neutral or enjoyable activities. Implications for measurement of morning-evening orientation are discussed. (C) 2002 Elsevier Science Ltd. All rights reserved.

Applications of accurate, high-precision Pb isotope ratio measurement by multi-collector ICP-MS

The isotope composition of Ph is difficult to determine accurately due to the lack of a stable normalisation ratio. Double and triple-spike addition techniques provide one solution and presently yield the most accurate measurements. A number of recent studies have claimed that improved accuracy and precision could also be achieved by multi-collector ICP-MS (MC-ICP-MS) Pb-isotope analysis using the addition of Tl of known isotope composition to Pb samples. In this paper, we verify whether the known isotope composition of Tl can be used for correction of mass discrimination of Pb with an extensive dataset for the NIST standard SRM 981, comparison of MC-ICP-MS with TIMS data, and comparison with three isochrons from different geological environments. When all our NIST SRM 981 data are normalised with one constant Tl-205/Tl-203 of 2.38869, the following averages and reproducibilities were obtained: Pb-207/Pb-206=0.91461+/-18; Pb-208/Ph-206 = 2.1674+/-7; and (PbPh)-Pb-206-Ph-204 = 16.941+/-6. These two sigma standard deviations of the mean correspond to 149, 330, and 374 ppm, respectively. Accuracies relative to triple-spike values are 149, 157, and 52 ppm, respectively, and thus well within uncertainties. The largest component of the uncertainties stems from the Ph data alone and is not caused by differential mass discrimination behaviour of Ph and Tl. In routine operation, variation of sample introduction memory and production of isobaric molecular interferences in the spectrometer's collision cell currently appear to be the ultimate limitation to better reproducibility. Comparative study of five different datasets from actual samples (bullets, international rock standards, carbonates, metamorphic minerals, and sulphide minerals) demonstrates that in most cases geological scatter of the sample exceeds the achieved analytical reproducibility. We observe good agreement between TIMS and MC-ICP-MS data for international rock standards but find that such comparison does not constitute the ultimate. test for the validity of the MC-ICP-MS technique. Two attempted isochrons resulted in geological scatter (in one case small) in excess of analytical reproducibility. However, in one case (leached Great Dyke sulphides) we obtained a true isochron (MSWD = 0.63) age of 2578.3 +/- 0.9 Ma, which is identical to and more precise than a recently published U-Pb zircon age (2579 3 Ma) for a Great Dyke websterite [Earth Planet. Sci. Lett. 180 (2000) 1-12]. Reproducibility of this age by means of an isochron we regard as a robust test of accuracy over a wide dynamic range. We show that reliable and accurate Pb-isotope data can be obtained by careful operation of second-generation MC-ICP magnetic sector mass spectrometers. (C) 2002 Elsevier Science B.V. All rights reserved.

Effect of varying levels of mental workload on startle eyeblink modulation

Previous research using punctuate reaction time and counting tasks has found that the startle eyeblink reflex is sensitive to attentional demands. The present experiment explored whether startle eyeblink is also modulated during a complex continuous task and is sensitive to different levels of mental workload. Participants (N=14) performed a visual horizontal tracking task either alone (single-task condition) or in combination with a visual gauge monitoring task (multiple-task condition) for three minutes. On some task trials, the startle eyeblink reflex was elicited by a noise burst. Results showed that startle eyeblink was attenuated during both tasks and that the attenuation was greater during the multiple-task condition than during the single-task condition. Subjective ratings, endogenous eyeblink rate, heart period, and heart period variability provided convergent validity of the workload manipulations. The findings suggest that the startle eyeblink is sensitive to the workload demands associated with a continuous visual task. The application of startle eyeblink modulation as a workload metric and the possibility that it may be diagnostic of workload demands in different stimulus modalities is discussed.

Aggregated personality, climate and demographic factors as predictors of departmental shrinkage

The present study investigated how demographic, personality, and climate variables act to predict departmental theft. Participants in the current field survey were 153 employees from 17 departments across two stores. The results of confirmatory factor analyses supported the construct validity of the Big Five Inventory (John, Donahue, & Kentle, 1991) and the Occupational Climate Questionnaire (Furnham & Gunter, 1997) in UK work settings. The results of regression analysis indicate that the variability in departmental theft is accountable in terms of a linear combination of demographic, personality, and climate factors. We concluded that an expanded theoretical perspective (utilizing demographic, personality, and climate variables) explained more variance than might otherwise be expected from any single perspective. Indeed, climate, personality, and demographic variables operated legitimately at the departmental level. Finally, we explained aggregated personality as a form of social interaction which is the by-product of individual differences.

The development and psychometric properties of a measure of social and adaptive functioning for children and adolescents

Developed, piloted, and examined the psychometric properties of the Child and Adolescent Social and Adaptive Functioning Scale (CASAFS), a self-report measure designed to examine the social functioning of young people in the areas of school performance, peer relationships, family relationships, and home duties/self-care. The findings of confirmatory and exploratory factor analysis support a 4-factor solution consistent with the hypothesized domains. Fit indexes suggested that the 4-correlated factor model represented a satisfactory solution for the data, with the covariation between factors being satisfactorily explained by a single, higher order factor reflecting social and adaptive functioning in general. The internal consistency and 12-month test-retest reliability of the total scale was acceptable. A significant, negative correlation was found between the CASAFS and a measure of depressive symptoms, showing that high levels of social functioning are associated with low levels of depression. Significant differences in CASAFS total and subscale scores were found between clinically depressed adolescents and a matched sample of nonclinical controls. Adolescents who reported elevated but subclinical levels of depression also reported lower levels of social functioning in comparison to nonclinical controls.

Are tryptophan and 5-hydroxytryptophan effective treatments for depression? A meta-analysis

Objective: To review the literature regarding the effectiveness of 5-hydroxytryptophan (5-HT) and L-tryptophan in the treatment of unipolar depression. Methods: A systematic review of the literature from 1966 to 2000 using the search terms 'tryptophan', 5-hydroxytryptophan', '5-HTP', '5-HT' and 'depression'. We extracted and grouped data for meta-analysis by pooling odds ratios (OR) and relative risks where possible. Results: One hundred and eight studies were located of which only two studies, one of 5-HT and one of L-tryptophan, with a total of 64 patients met sufficient quality criteria to be included. These studies suggest 5-HT and L-tryptophan are better than placebo at alleviating depression (Peto OR = 4.1, 95% CI = 1.3-13.2). However, the small size of the studies, and the large number of inadmissible, poorly executed studies, casts doubt on the result from potential publication bias, and suggests that they are insufficiently evaluated to assess their effectiveness. Conclusions: A large body of evidence was subjected to very basic criteria for assessing reliability and validity, and was found to largely be of insufficient quality to inform clinical practice. More well-designed studies are urgently required to enable an assessment of what may be an effective class of agents.

Screening for vulnerability to abuse among older women: Women's health Australia study

The validity of a brief self-report screening measure for elder abuse was examined on a nationally representative sample of more than 12,000 older women it? the baseline survey of the Australian Longitudinal Study on Women's Health. The screening instrument was a modification Of the Hwalek-Sengstock Elder Abuse Screening Test. Construct validity was examined using factor analysis and correlation with a wide range of sociodemographic, psychological. and health-related variables. Four factors, each of three items, were identified representing the following domains: Vulnerability, Dependence, Dejection, and Coercion. The Vulnerability and Coercion factors had the highest face validity for abuse and demonstrated moderate to good construct validity. The six items comprising these factors may provide a simple screening tool for elder abuse The identified correlates of abuse indicators have the potential to enhance policy development, screening, intervention, and carer support programs.

Appropriate indicators for injury control?

Indicators are valuable tools used to measure progress towards a desired health outcome. Increased awareness of the public health burden due to injury has lead to a concomitant interest in monitoring the impact of national initiatives that aim to reduce the size of the burden. Several injury indicators have now been proposed. This study examines the ability of each of the suggested indicators to reflect the nature and extent of the burden of non-fatal injury. A criterion validity, population-based, prospective cohort study was conducted in Brisbane, a sub-tropical Metropolitan City on the eastern seaboard of Australia, over a 12-month period between 1 January and 31 December 1998. Neither the presence of a long bone fracture nor the need for hospitalisation for 4 or more days were sensitive or specific indicators for 'serious' or major injury as defined by the 'Gold Standard' Injury Severity Score (ISS). Subsequent analysis, using other public health outcome measures demonstrated that the major component of the illness burden of injury was in fact due to 'minor' not serious injury. However, the suggested indicators demonstrated low sensitivity and specificity for these outcomes as well. The results of the study support the need to include at least all hospitalisations in any population-based measure of injury and not attempt to simplify the indicator to a more convenient measure aimed at identifying just those cases of,serious' injury.

Novel genes regulated by Sonic Hedgehog in pluripotent mesenchymal cells

Sonic Hedgehog is a secreted morphogen involved in patterning a wide range of structures in the developing embryo. Disruption of the Hedgehog signalling cascade leads to a number of developmental disorders and plays a key role in the formation of a range of human cancers. The identification of genes regulated by Hedgehog is crucial to understanding how disruption of this pathway leads to neoplastic transformation. We have used a Sonic Hedgehog (Shh) responsive mouse cell line, C3H/10T1/2, to provide a model system for hedgehog target gene discovery. Following activation of cell cultures with Shh, RNA was used to interrogate microarrays to investigate downstream transcriptional consequences of hedgehog stimulation. As a result 11 target genes have been identified, seven of which are induced (Thrombomodulin, GILZ, BF-2, Nr4a1, IGF2, PMP22, LASP1) and four of which are repressed (SFRP-1, SFRP-2, Mip1-gamma, Amh) by Shh. These targets have a diverse range of putative functions and include transcriptional regulators and molecules known to be involved in regulating cell growth or apoptosis. The corroboration of genes previously implicated in hedgehog signalling, along with the finding of novel targets, demonstrates both the validity and power of the C3H/10T1/2 system for Shh target gene discovery.

The rheology of flotation froths

A literature review has highlighted the need to measure flotation froth rheology in order to fully characterise the role of the froth in the flotation process. The initial investigation using a coaxial cylinder viscometer for froth rheology measurement led to the development of a new device employing a vane measuring head. The modified rheometer was used in industrial scale flotation tests at Mt. Isa Copper Concentrator. The measured froth rheograms show a non-Newtonian nature for the flotation froths (pseudoplastic flow). The evidence of the non-Newtonian flow has questioned the validity of application of the Laplace equation in froth motion modelling as used by a number of researchers, since the assumption of irrotational flow is violated. Correlations between the froth rheology and the froth retention time, water hold-up in the froth and concentrate grades have been found. These correlations are independent of air flow rate (test data at various air flow rates fall on one similar trend line). This implies that froth rheology may be used as a lumped parameter for other operating variables in flotation modelling and scale up. (C) 2003 Elsevier Science B.V. All rights reserved.

Identifying the communication activities of older people with aphasia: Evidence from naturalistic observation

Background: Increasingly there is a call from clinicians and researchers for measures that document the impact of aphasia on a person's everyday communication. Do existing assessments of communication disability adequately sample communication activities relevant to our clients? Communication skills and networks change with age. A need exists to determine the everyday communication activities of older people and in particular those with aphasia. Aims: The primary aim of this study was to describe and compare the everyday communication activities of older people with aphasia and healthy older people who are living in the community. A secondary aim was to investigate the content validity of the American Speech-Language Hearing Association Functional Assessment of Communication Skills for Adults (ASHA FACS, 1997) for older Australians. Methods & Procedures: Naturalistic observation was the method of choice for detailing the everyday communication of 15 older people with chronic aphasia following stroke and a matched group of 15 healthy older people who were living in the community. Researchers, in the role of participant observer, took field notes for 8 hours, over three occasions within a week. A total of 240 hours of observation have been coded in terms of communication activity, topic, communication partners, and place of communication. A brief 5-day diary served to check the representativeness of the observational data. After each hour of observation, the researcher checked which ASHA FACS items had been observed. Outcomes & Results: Naturalistic observation provided a rich, rigorous, and systematic methodology for detailing the dynamics and complexities of authentic communication. The most common communication activities for both groups were conversations at home and in social groups. Real-life communication was revealed to serve the dual purposes of transaction and interaction. Results indicate that older people with aphasia engage in similar communication activities to healthy older people although differences were evident in the frequency of communication and in specific activities such as story telling, writing, commenting, and acknowledging. ASHA FACS items were generally relevant to older Australians living in the community. Conclusions: This study demonstrated that communication activity is multifaceted in terms of the type of communication and contextual factors. The observational data describe the effects of aphasia on a person's everyday communication activity and reveal the impact of aphasia on the social functions of communication including sharing information, maintaining and establishing relationships, and telling one's story. Functional communication assessment requires a greater focus on the interactional and uniquely interpersonal aspects of social communication.

Can the Internet be used as a medium to evaluate knee angle?

Telemedicine promises to revolutionize medical care delivery in rural and remote areas. The ability to accurately evaluate physical impairment via the Internet is important to the possible future provision of Internet-based physiotherapy. This study evaluated the reliability and validity of assessing knee range of motion via the Internet. Two therapists evaluated knee angle on a single subject via two methods of assessment: the Internet and the traditional method (face-to-face). Nine random positions of the knee were chosen with the principal examiner performing 20 face-to-face and two sets of 20 Internet measures in each position (n=540). The secondary therapist performed Internet assessments only. The Internet connection was established at a readily available speed of 17 kbit/s. The Internet-based goniometer was found to be a valid tool for measuring both knee flexion and extension angles. It was shown to possess both high intra and inter-rater reliability. Difference average plots of the scores verified the consistency of measurement between both modes of assessment. The successful evaluation of the physical outcome measure of knee range of motion via the Internet assists the further development of Internet-based physiotherapy applications. (C) 2003 Elsevier Science Ltd. All rights reserved.