On the existence of solutions to boundary value problems on time scales

This work formulates existence theorems for solutions to two-point boundary value problems on time scales. The methods used include maximum principles, a priori bounds and topological degree theory.

Rainfall variability at decadal and longer time scales: signal or noise?

Rainfall variability occurs over a wide range of temporal scales. Knowledge and understanding of such variability can lead to improved risk management practices in agricultural and other industries. Analyses of temporal patterns in 100 yr of observed monthly global sea surface temperature and sea level pressure data show that the single most important cause of explainable, terrestrial rainfall variability resides within the El Nino-Southern Oscillation (ENSO) frequency domain (2.5-8.0 yr), followed by a slightly weaker but highly significant decadal signal (9-13 yr), with some evidence of lesser but significant rainfall variability at interclecadal time scales (15-18 yr). Most of the rainfall variability significantly linked to frequencies tower than ENSO occurs in the Australasian region, with smaller effects in North and South America, central and southern Africa, and western Europe. While low-frequency (LF) signals at a decadal frequency are dominant, the variability evident was ENSO-like in all the frequency domains considered. The extent to which such LF variability is (i) predictable and (ii) either part of the overall ENSO variability or caused by independent processes remains an as yet unanswered question. Further progress can only be made through mechanistic studies using a variety of models.

A review of the psychometric properties of the Health of the Nation Outcomes Scales (HoNOS) family of measures

BACKGROUND: The Health of the Nation Outcome Scales was developed to routinely measure outcomes for adults with mental illness. Comparable instruments were also developed for children and adolescents (the Health of the Nation Outcome Scales for Children and Adolescents) and older people (the Health of the Nation Outcome Scales 65+). All three are being widely used as outcome measures in the United Kingdom, Australia and New Zealand. There is, however, no comprehensive review of these instruments. This paper fills this gap by reviewing the psychometric properties of each. METHOD: Articles and reports relating to the instruments were retrieved, and their findings synthesised to assess the instruments' validity (content, construct, concurrent, predictive), reliability (test-retest, inter-rater), sensitivity to change, and feasibility/utility. RESULTS: Mostly, the instruments perform adequately or better on most dimensions, although some of their psychometric properties warrant closer examination. CONCLUSION: Collectively, the Health of the Nation Outcome Scales family of measures can assess outcomes for different groups on a range of mental health-related constructs, and can be regarded as appropriate for routinely monitoring outcomes.

Heritability and nineteen-year stability of long and short EPQ-R Neuroticism scales

The heritability and stability over a 19 year period of long (23-item) and short (12-item) versions of Eysenck's Neuroticism scale were compared in a large Australian twin-family sample. Stability over 19 years of the 23-item Neuroticism scale was 0.62 and for the 12-item scale 0.59. Correlations between scores obtained by mailed questionnaire and telephone interview a few weeks apart were 0.87 for the long scale and 0.85 for the short scale; scores obtained by mail were slightly higher, particularly for females. The 12-item scale had slightly reduced power to discriminate both high and low scoring individuals on the full 23-item scale. Mean Neuroticism score for the 12-item scale was atypically low when compared to the distribution of the complete set of scores for all possible combinations (> 1 million) of 12-items drawn from the full 23-item EPQ-R. Mean heritabilities for the lowest and highest 300,000 of these combinations were 43.2% and 42.7%, respectively, somewhat higher than the 41.0% for the actual EPQ-R-S 12-item scale. Heritability for the 23-item scale was 46.5%. We conclude that there is little loss of either stability or heritability in using the short EPQ-R scale, but the choice of which 12-items could have been better. (c) 2005 Elsevier Ltd. All rights reserved.

Conceptual distinctions among Carver and White's (1994) BAS scales: A reward-reactivity versus trait impulsivity perspective

The 'BIS/BAS scales' (Carver & White, 1994) is the most widely cited inventory for assessing Gray's (1982,1991) Reinforcement Sensitivity Theory (RST) of personality. A peculiarity of this instrument is its three-factor representation of Gray's Behavioural Activation System (BAS), which mediates reactions to reward. While the BAS was initially proposed as the causal basis of Impulsivity, recent arguments suggest that Impulsivity is related to but distinct from reward-reactivity. In this paper, two studies examined Carver and White's BAS scales in terms of factor structure, and convergent/divergent validity when predicting proxies of Impulsivity and reward-reactivity. Confirmatory Factor Analysis revealed structural distinctions between the three BAS scales, and multivariate regression suggested that two of the scales (Drive and Reward-Responsiveness) reflect key concepts of the BAS, while the third (Fun-Seeking) has a broader focus, being equally related to reward-reactivity and Impulsivity. (c) 2005 Elsevier Ltd. All rights reserved.

The MMPI-2 Gender-Masculine and Gender-Feminine scales: Gender roles as predictors of psychological health in clinical patients

Previous research measuring various biosocial factors such as age, sex, and marital status has found them to be essentially unrelated to measures of psychological health. Recent empirical studies have revealed that personality constructs may be more significant than demographic variables in the prediction of psychological well-being. The present study assessed the personality constructs of masculinity and femininity and hypothesized that the Gender-Masculine ( GM) scale of the MMPI-2 would be more effective than the Gender-Feminine (GF) scale in predicting psychological well-being. This hypothesis stems from previous research that has indicated the dominance of the masculinity model. It is suggested that previous research supporting androgyny as a primary indicator of well-being was influenced by the masculinity component of this gender orientation. One hundred and seventy-seven psychiatric patients from Australia (N = 107) and Singapore ( N 5 70) completed the MMPI-2. Hierarchical multiple regression revealed significantly stronger masculinity effects, with significance achieved on measures of ego strength and low self-esteem. No significant relationship between psychological well-being and the GF variable was found. Similarly, androgyny did not add any further variance to the model when masculinity was controlled for. Overall, the results are consistent with an interpretation that GM is a better correlate of psychological well-being as compared to the GF scale.

Using Rasch modeling to re-evaluate three scales related to physical activity: Enjoyment, perceived benefits and perceived barriers

Studies suggest that enjoyment, perceived benefits and perceived barriers may be important mediators of physical activity. However, the psychometric properties of these scales have not been assessed using Rasch modeling. The purpose of this study was to use Rasch modeling to evaluate the properties of three scales commonly used in physical activity studies: the Physical Activity Enjoyment Scale, the Benefits of Physical Activity Scale and the Barriers to Physical Activity Scale. The scales were administered to 378 healthy adults, aged 25–75 years (50% women, 62% Whites), at the baseline assessment for a lifestyle physical activity intervention trial. The ConQuest software was used to assess model fit, item difficulty, item functioning and standard error of measurement. For all scales, the partial credit model fit the data. Item content of one scale did not adequately cover all respondents. Response options of each scale were not targeting respondents appropriately, and standard error of measurement varied across the total score continuum of each scale. These findings indicate that each scale's effectiveness at detecting differences among individuals may be limited unless changes in scale content and response format are made.

A review of placoderm scales, and their significance in placoderm phylogeny

An historical review of the literature relating to placoderm scales preserved in association with articulated dermal plates, or as isolated units in microvertebrate assemblages, is followed by a discussion of their relevance in phylogenetic analyses of the Placodermi. The dentinous tissue forming the tubercles of Early Devonian acanthothoracid scales and dermal bone is similar to that of the dermal bone ornament of some osteostracans, and denticles of the vertebrate Skiichthys from the Ordovician Harding Sandstone. This similarity supports the proposition that the gnathostomes are the sister-group of the Osteostraci, with the Placodermi branching earliest within the gnathostomes, and the Acanthothoraci branching earliest within the Placodermi. The meso-semidentine in acanthothoracid tubercles, rather than semidentine (sensu stricto), is most likely to be synapomorphic for the Placodermi.

Optimising state of environment monitoring at multiple scales using remotely sensed data

Proceedings of the 11th Australasian Remote Sensing and Photogrammetry Conference