ANU Research Publications

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The Australian National University's Research Publications collection is an online location for collecting, preserving and disseminating the scholarly output of the University. This service allows members of the University to share their research with the wider community. ANU Open Research accepts journal articles, conference papers, book chapters, working or technical papers and other forms of scholarly communication.

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  • ItemOpen Access
    Large-area epitaxial growth of InAs nanowires and thin films on hexagonal boron nitride by metal organic chemical vapor deposition
    (Institute of Physics Publishing, 2023) Gopakumar Saraswathyvilasam, Aswani; Adhikari, Sonachand; Gupta, Bikesh; Balendhran, Sivacarendran; Higashitarumizu, Naoki; Tournet, Julie; Li, Li; Javey, Ali; Crozier, Kenneth; Karuturi, Siva; Jagadish, Chennupati; Tan, Hoe
    Large-area epitaxial growth of III–V nanowires and thin films on van der Waals substrates is key to developing flexible optoelectronic devices. In our study, large-area InAs nanowires and planar structures are grown on hexagonal boron nitride templates using metal organic chemical vapor deposition method without any catalyst or pre-treatments. The effect of basic growth parameters on nanowire yield and thin film morphology is investigated. Under optimised growth conditions, a high nanowire density of 2.1 109 cm−2 is achieved. A novel growth strategy to achieve uniform InAs thin film on h-BN/SiO2/Si substrate is introduced. The approach involves controlling the growth process to suppress the nucleation and growth of InAs nanowires, while promoting the radial growth of nano-islands formed on the h-BN surface. A uniform polycrystalline InAs thin film is thus obtained over a large area with a dominant zinc-blende phase. The film exhibits near-band-edge emission at room temperature and a relatively high Hall mobility of 399 cm−2/(Vs). This work suggests a promising path for the direct growth of large-area, low-temperature III–V thin films on van der Waals substrates.
  • ItemOpen Access
    Electrical and thermal conductivity in graphene-enhanced carbon-fibre/PEEK: The effect of interlayer loading
    (Pergamon-Elsevier Ltd, 2023) Leow, Christopher; Kreider, Peter; Sommacal, Silvano; Kluth, Patrick; Compston, Paul
    Combining graphene at different loadings with composites offers the possibility of tailored electrical and thermal properties for the aerospace sector, including electrostatic dissipation, thermal management and lightning strike protection applications. The effects of interlaminar graphene loadings to impart property enhancement in fibre reinforced thermoplastic composites remains unknown. Spray deposition offers a highly scalable, and rapid method to embed graphene. This study investigates the application of spray-deposited graphene suspension synthesised via liquid phase exfoliation (LPE) to functionalise carbon fibre/polyether ether ketone (CF/PEEK) composites. LPE graphene suspensions were spray deposited onto CF/PEEK prepreg ply substrates to create smooth thin films. With increased deposition time the graphene thin film root mean squared roughness decreased from 3.51 μm to 2.52 μm. The addition of 0.25 wt%, 0.7 wt% and 1.1 wt% graphene to the interlaminar regions in consolidated CF/PEEK imparted enhanced electrical and thermal conductivity. Electrical conductivity enhancement of up to ∼252% transverse to the fibre direction and up to ∼204% through thickness was measured after the addition of 0.25 wt% graphene. Thermal diffusivity increased up to ∼183% through-thickness, while 61% in the transverse to the fibre direction with 0.7 wt% additions. However, increased graphene loading also increased the void content in the composite resulting in reduced shear strength. Excess surfactant vapourisation during high temperature processing likely created voids up to 2.8 vol% often located within the interply and interlaminar region hindering anisotropic conductivity enhancement. Nevertheless, graphene loadings within the interlaminar region show promise in imparting bulk property enhancement.
  • ItemOpen Access
    Linking water use efficiency with water use strategy from leaves to communities
    (Cambridge University Press, 2023) Liang, Jie; Krauss, Ken W; Finnigan, John; Stuart-Williams, Hilary; Farquhar, Graham; Ball, Marilyn
    Limitations and utility of three measures of water use characteristics were evaluated: water use efficiency (WUE), intrinsic WUE and marginal water cost of carbon gain ((Formula presented.)) estimated, respectively, as ratios of assimilation (A) to transpiration (E), of A to stomatal conductance (gs) and of sensitivities of E and A with variation in gs. Only the measure (Formula presented.) estimates water use strategy in a way that integrates carbon gain relative to water use under varying environmental conditions across scales from leaves to communities. This insight provides updated and simplified ways of estimating (Formula presented.) and adds depth to understanding ways that plants balance water expenditure against carbon gain, uniquely providing a mechanistic means of predicting water use characteristics under changing environmental scenarios.
  • ItemOpen Access
    Camera-based automated monitoring of flying insects in the wild (Camfi). II. flight behaviour and long-term population monitoring of migratory Bogong moths in Alpine Australia
    (Frontiers Media SA, 2023) Wallace, Jesse; Dreyer, David; Reber, Therese; Khaldy, Lana; Mathews-Hunter, Benjamin; Green, Ken; Zeil, Joachim; Warrant, Eric
    Introduction: The Bogong moth Agrotis infusa is well known for its remarkable annual round-trip migration from its breeding grounds across eastern and southern Australia to its aestivation sites in the Australian Alps, to which it provides an important annual influx of nutrients. Over recent years, we have benefited from a growing understanding of the navigational abilities of the Bogong moth. Meanwhile, the population of Bogong moths has been shrinking. Recently, the ecologically and culturally important Bogong moth was listed as endangered by the IUCN Red List, and the establishment of a program for long-term monitoring of its population has been identified as critical for its conservation. Methods: Here, we present the results of two years of monitoring of the Bogong moth population in the Australian Alps using recently developed methods for automated wildlife-camera monitoring of flying insects, named Camfi. While in the Alps, some moths emerge from the caves in the evening to undertake seemingly random flights, filling the air with densities in the dozens per cubic metre. The purpose of these flights is unknown, but they may serve an important role in Bogong moth navigation. Results: We found that these evening flights occur throughout summer and are modulated by daily weather factors. We present a simple heuristic model of the arrival to and departure from aestivation sites by Bogong moths, and confirm results obtained from fox-scat surveys which found that aestivating Bogong moths occupy higher elevations as the summer progresses. Moreover, by placing cameras along two elevational transects below the summit of Mt. Kosciuszko, we found that evening flights were not random, but were systematically oriented in directions relative to the azimuth of the summit of the mountain. Finally, we present the first recorded observations of the impact of bushfire smoke on aestivating Bogong moths – a dramatic reduction in the size of a cluster of aestivating Bogong moths during the fire, and evidence of a large departure from the fire-affected area the day after the fire. Discussion: Our results highlight the challenges of monitoring Bogong moths in the wild and support the continued use of automated camera-based methods for that purpose.
  • ItemEmbargo
    Ferri-hydrite: A Novel Electron-Selective Contact Layer for InP Photovoltaic and Photoelectrochemical Cells
    (American Chemical Society, 2023) Gupta, Bikesh; Zhang, Doudou; Chen, Hongjun; Jagadish, Chennupati; Tan, Hoe; Karuturi, Siva
    Solar energy conversion devices with charge-selective contacts are attracting significant research interest as a cost-effective alternative to homojunction counterparts. This study presents a novel approach for fabricating high-performance solar cells based on InP heterojunctions using a solution-processed ferri-hydrite (Fh) electron-selective contact (ESC). The champion cell efficiency of 16.6% is achieved, which is a significant improvement over those from previous studies using other solution-processed ESC materials. X-ray photoelectron spectroscopy measurements showed that the low conduction band offset at the Fh–InP interface facilitated selective transport of photogenerated electrons from InP. Moreover, the Fh electron-selective contact layer provided an excellent photoelectrochemical half-cell water reduction efficiency of 8.4%. The Fh layer not only selectively extracts photogenerated electrons from InP but also simultaneously serves as a surface protection layer, improving the cell’s long-term stability. These results demonstrate the potential of Fh as a low-cost and easily fabricated material for use in high-efficiency photovoltaic and photoelectrochemical devices. Our findings pave the way for further improvements in the efficiency of InP heterojunction solar cells by addressing the losses incurred in the cells.
  • ItemEmbargo
    Cobalt modification of nickel-iron hydroxide electrocatalysts: a pathway to enhanced oxygen evolution reaction
    (RSC Publications, 2023) Soo, Joshua Zheyan; Riaz, Asim; Kremer, Felipe; Brink, Frank; Jagadish, Chennupati; Tan, Hoe; Karuturi, Siva
    We present a two-step method for synthesizing high-performing NiFeCo hydroxide electrocatalysts by introducing cobalt into as-synthesized NiFe layered double hydroxide (LDH) using a versatile solution corrosion approach. Our results indicate that cobalt modification significantly reduces the charge transfer resistance, and increases the catalyst turnover frequency, while preserving the integrity of the NiFe LDH layer. With these enhancements, ternary NiFeCo hydroxide obtained an overpotential of 195 mV at 10 mA cm-2, significantly outperforming binary NiFe LDH (264 mV). Additionally, we demonstrate that the choice of metal precursors and their concentrations can greatly impact the morphology and OER performance of NiFeCo hydroxide, particularly in attaining high current densities. Optimizing the precursor concentration is crucial to avoid adverse effects, such as increased charge transfer resistance. The demonstrated performance positions this NiFeCo hydroxide as a promising catalyst for industrial-scale water-splitting applications, highlighting the potential of our modification technique for further development of efficient electrocatalysts.
  • ItemOpen Access
    Roundtable on John Clark's The Asian Modern
    (MIT Press, 2023) Juneja, Monica; Minglu, Gao; Sambrani, Chaitanya; Taylor, Nora Annesley; Tiampo, Ming
    The book, The Asian Modern, by John Clark (with an Introduction by the Manila-based critic and curator, Patrick Flores) seeks to construct a “cross-Asian” account through a detailed historical and empirical focus on 30 artists spanning Southeast, East, and South Asia, as well as Australia. At the core of the book is the premise that the given place, “Asia,” is the locus for a critique of the normative account of modernism tethered to another locale, identified by Clark as “Euramerica.” These focused geographic arenas provide the basis for novel itineraries, dynamic dispersals, and alternative sightlines that reject the conventional frame of the nation. Given the ambitious scale and scope of Clark's project, the ARTMargins editors invited five historians of modern and contemporary art in Asia—Monica Juneja, Ming Tiampo, Nora Taylor, Gao Minglu, and Chaitanya Sambrani—to critically reflect upon the methodological and scholarly implications of his undertaking for the narratives of art history in Asia and beyond. Their responses point up both the limits and merits of The Asian Modern, and address important themes and debates in approaches to global art history, more broadly.
  • PublicationOpen Access
    Using Machine Learning Techniques for Phylogenetics
    (2022) Chen Yang
    Phylogenetics is the study of analyzing genes to infer evolutionary relationships among a set of species. Maximum likelihood and maximum parsimony are two typical methods for phylogenetic inference, but each of these two methods could perform well or badly for different phylogenetic tree types, resulting in inconsistent phylogenetic trees. This thesis trained a neural network to infer the phylogenetic tree type from a four-taxon alignment, which potentially provides insight into which tree reconstruction method is suitable to the alignment.
  • ItemOpen Access
    Past rainfall patterns in Southeast Asia revealed by microanalysis of δ18O values in human teeth
    (Elsevier, 2024) Vaiglova, Petra; Avila, Janaina N.; Buckley, Hallie; Galipaud, Jean-Christophe; Green, Daniel R; Halcrow, Sian; James, Hannah F.; Kinaston, Rebecca; Oxenham, Marc; Paz, Victor; Simanjuntak, Truman; Snoeck, Christophe; Trinh, Hiep Hoang; Williams, Ian; Smith, Tanya
    Variations in human subsistence and settlement patterns have been documented at Holocene archaeological sites across Island and Mainland Southeast Asia. Although climate is frequently invoked as a causal mechanism underlying this variation, direct evidence of ancient rainfall variability on the scale of human lifetimes has thus far been elusive. Here we use a novel time-resolute method for in situ measurement of human tooth enamel δ18O values (n =2629 near-weekly measurements sampling 51 years) to assess past rainfall seasonality patterns in Southeast Asia. Seasonal fluctuations in enamel δ18O values of ancient humans from several different periods are compared to modern rainfall recorded in Vietnam, Philippines, and Indonesia by the Global Network in Isotopes in Precipitation (GNIP). The likelihood that the ancient humans reflect local precipitation patterns is established through measurement of bulk enamel 87Sr/86Sr ratios. Comparison of the archaeological individuals and the modern rainfall datasets shows that the seasonal variabilities in ancient δ18Oenamel are consistent with seasonal variabilities in modern δ18Oprecip across the study locations (highest in Vietnam, lowest in Indonesia, intermediate in the Philippines). Strong seasonal δ18Oenamel trends in four of five hunter-gatherers from Con Co Ngua, Vietnam, facilitate the inference of birth approximately six months prior to the onset of monsoons, consistent with tropical subsistence societies where food availability correlates with rainfall. High-resolution analysis of human tooth enamel represents a powerful new tool for seasonality reconstructions across different regional and climatic settings.
  • ItemEmbargo
    Bullying in the Military: Do the Effects on Mental Health and Wellbeing Depend on the Source?
    (Taylor & Francis Online, 2023) Steele, Nicole; Fogarty, Gerard J.; Rodgers, Bryan
    The current study explored the prevalence and consequences of being bullied by coworkers, subordinates, and/or superiors within 21 Australian Defence Force units (N = 2,960). Data were collected as part of an organizational climate survey administered to each unit at the request of the unit commander. Bullying from multiple sources was more common than bullying from a single source, indicating climates of workplace bullying. Of the 945 respondents (31.9%) who reported experiencing workplace bullying, coworkers and superiors were the main sources either in isolation or in combination with other levels in the organization. Furthermore, there was evidence that the impact varied according to source. Compared to bullying from coworkers or subordinates, more detrimental effects were experienced when superiors were the sole source of workplace bullying; 23.6% of respondents in this situation reported ongoing distress or having to seek medical/mental health care. The associations between experiencing bullying and psychological distress, affective commitment, and job satisfaction were also stronger when superiors were the source of bullying. These results emphasize the importance of supervisors showing respect to all employees. Bullying behaviors are likely to be copied, creating climates where bullying can come from multiple sources, with consequent negative effects on the targets of these behaviors.
  • ItemEmbargo
    Power and the planetary health equity crisis
    (The Lancet Publishing Group, 2022) Friel, Sharon; Arthur, Megan; Frank, Nicholas
    Planetary health equity—the environmentally sustainable and equitable enjoyment of good health—is in crisis as climate change ravages global populations through increased temperatures, wildfires, and increasingly severe and frequent storms, flooding, and landslides.1 Ecosystem collapse is a real threat in Australia.2 Health inequities are likely to worsen as pre-existing inequities ensure that socially disadvantaged groups and people in low-income and middle-income countries are disproportionately affected by climate change.
  • ItemEmbargo
    A short form of the Positive and Negative Affect Schedule: Evaluation of factorial validity and invariance across demographic variables in a community sample
    (Pergamon-Elsevier Ltd, 1999) Mackinnon, Andrew; Jorm, Anthony F; Christensen, Helen; Korten, Ailsa; Jacomb, Trish; Rodgers, Bryan
    The existence of two nearly-orthogonal dimensions of positive and negative affect was established for a ten-item short form of the Positive and Negative Affect Schedule using confirmatory factor analytic techniques in a large probability sample (n=2651) spanning ages 18 to 79. The factor structure and factor correlations were found to be unchanged with age. A multiple indicators, multiple causes model was used to investigate differences in item responses according to age, sex, education, marital status and financial hardship that could not be accounted for by differences in affect levels between groups. Only one item, excited from the Positive Affect scale, was found to elicit differential responses. While improvements to the Positive Affect scale might be desirable, the Short PANAS can be recommended for use when measures of positive and negative affect are required.
  • ItemOpen Access
    Flexible Correct-By-Construction Programming
    (International Federation of Computational Logic (IfCoLog), 2023) Runge, Tobias; Bordis, Tabea; Potanin, Alex; Thum, Thomas; Schaefer, Ina
    Correctness-by-Construction (CbC) is an incremental program construction process to construct functionally correct programs. The programs are constructed stepwise along with a specification that is inherently guaranteed to be satisfied. CbC is complex to use without specialized tool support, since it needs a set of predefined refinement rules of fixed granularity which are additional rules on top of the programming language. Each refinement rule introduces a specific programming statement and developers cannot depart from these rules to construct programs. CbC allows to develop software in a structured and incremental way to ensure correctness, but the limited flexibility is a disadvantage of CbC. In this work, we compare classic CbC with CbC-Block and Trait-CbC. Both approaches CbC-Block and Trait-CbC, are related to CbC, but they have new language constructs that enable a more flexible software construction approach. We provide for both approaches a programming guideline, which similar to CbC, leads to well-structured programs. CbC-Block extends CbC by adding a refinement rule to insert any block of statements. Therefore, we introduce CbC-Block as an extension of CbC. Trait-CbC implements correctness-by-construction on the basis of traits with specified methods. We formally introduce Trait-CbC and prove soundness of the construction strategy. All three development approaches are qualitatively compared regarding their programming constructs, tool support, and usability to assess which is best suited for certain tasks and developers.
  • ItemEmbargo
    Validity of the Malaise Inventory in general population samples
    (Dr Dietrich Steinkopff Verlag, 1999) Rodgers, Bryan; Pickles, A.; Power, C.; Collishaw, S.; Maughan, B.
    Background: The Malaise Inventory is a commonly used self-completion scale for assessing psychiatric morbidity. There is some evidence that it may represent two separate psychological and somatic sub-scales rather than a single underlying factor of distress. This paper provides further information on the factor structure of the Inventory and on the reliability and validity of the total scale and two sub-scales. Methods: Two general population samples completed the full Inventory: over 11,000 subjects from the National Child Development Study at ages 23 and 33, and 544 mothers of adolescents included in the Isle of Wight epidemiological surveys. Results: The internal consistency of the full 24-item scale and the 15-item psychological sub-scale were found to be acceptable, but the eight-item somatic sub-scale was less reliable. Factor analysis of all 24 items identified a first main general factor and a second more purely psychological factor. Receiver operating characteristic (ROC) analysis indicated that the validity of the scale held for men and women separately and for different socio-economic groups, by reference to external criteria covering current or recent psychiatric morbidity and service use, and that the psychological sub-scale had no greater validity than the full scale. Conclusions: This study did not support the separate scoring of a somatic sub-scale of the Malaise Inventory. Use of the 15-item psychological sub-scale can be justified on the grounds of reduced time and cost for completion, with little loss of reliability or validity, but this approach would not significantly enhance the properties of the Inventory by comparison with the full 24-item scale. Inclusion of somatic items may be more problematic when the full scale is used to compare particular sub-populations with different propensities for physical morbidity, such as different age groups, and in these circumstances it would be a sensible precaution to utilise the 15-item psychological sub-scale.
  • ItemOpen Access
    Finite element interpolated neural networks for solving forward and inverse problems
    (Elsevier, 2023) Badia, Santiago; Li, Wei; MARTIN, ALBERTO F.
    We propose a general framework for solving forward and inverse problems constrained by partial differential equations, where we interpolate neural networks onto finite element spaces to represent the (partial) unknowns. The framework overcomes the challenges related to the imposition of boundary conditions, the choice of collocation points in physics-informed neural networks, and the integration of variational physics-informed neural networks. A numerical experiment set confirms the framework’s capability of handling various forward and inverse problems. In particular, the trained neural network generalises well for smooth problems, beating finite element solutions by some orders of magnitude. We finally propose an effective one-loop solver with an initial data fitting step (to obtain a cheap initialisation) to solve inverse problems.
  • ItemEmbargo
    Does financial hardship account for elevated psychological distress in lone mothers?
    (Elsevier, 1999) Hope, Steven; Power, Chris; Rodgers, Bryan
    Lone mothers have been shown to have higher levels of psychological distress than married mothers, but it is not clear how this difference arises. Using data from the 1958 British birth cohort followed to age 33, we investigated alternative explanations for the excess distress of lone mothers. Logistic regression models were used to estimate odds ratios for distress (measured using the Malaise Inventory) in lone vs married mothers. Odds ratios were adjusted to assess the contribution of explanatory factors. At age 33, psychological distress was greater among lone than married mothers (OR 2.59, 95% CI 1.97, 3.41). The odds ratio decreased to 1.43 (95% CI 1.02, 2.01) after adjustment for all explanatory factors (prior psychological distress, age of youngest child and number of children in the household, and contemporary measures of financial hardship, employment, and social support). Attenuation of the odds ratio was most marked after taking account of financial hardship. Psychological distress was greater among divorced mothers than never married mothers, though not significantly (OR=1.70, 95% CI 0.88, 3.28). This difference was not explained by the factors examined, and was not due to the immediate distress associated with a recent divorce. Elevated psychological distress of lone mothers appears to be related to financial hardship, while other explanations, including social support and selection, have a more modest impact. Not all of the elevated psychological distress among lone mothers was accounted for, particularly among divorced lone mothers
  • ItemEmbargo
    Heavy alcohol consumption and marital status: Disentangling the relationship in a national study of young adults
    (Taylor & Francis Ltd, 1999) Power, Chris; Rodgers, Bryan; HOPE, STEVEN
    AIMS: To investigate why alcohol consumption varies by marital status, assessing (i) differences in heavy consumption prior to changes in marital status (indicating selection) and increases or decreases in heavy consumption associated with changes in marital status (indicating causation), (ii) whether such increases or decreases are transient, and (iii) the possible mediating effect of parental status. DESIGN: Longitudinal cohort. SETTING: Great Britain. PARTICIPANTS: Data from the 23- and 33-year surveys of the 1958 British birth cohort (all born in England, Wales and Scotland, 3-9 March 1958). MEASUREMENTS: Heavy drinking, defined as more than 35 (men) and 20 (women) units/week; changes between ages 23 and 33 in consumption and marital status. FINDINGS: The divorced had the highest consumption levels at both ages, the married had the lowest. Selection effects were minimal in both sexes. Overall, heavy drinking declined between ages 23 and 33 (21.4-13.0% in men, 6.4-3.4% in women), but increased among individuals who divorced, compared to the continuously married (adjusted OR = 2.05, 95% CI = 1.49, 2.83 for men; OR = 2.61, 95% CI = 1.67, 4.09 for women), most strikingly for recent divorces (adjusted OR = 4.97, 95% CI = 2.86, 8.57 and OR = 5.25, 95% CI = 2.60, 10.65). High rates of heavy drinking persisted for never married men (19.1%) and women (5.2%). CONCLUSIONS: The heavy drinking level of divorced young adults was not due to selection. Marital separation was accompanied by increases in heavy drinking, with pronounced short-term effects. Adverse alcohol-related health consequences may occur in the immediate period around divorce. Individuals who never marry appear to have a chronic heavy consumption pattern that may contribute to their increased mortality.
  • ItemEmbargo
    Emotional response of participants to a mental health survey
    (Dr Dietrich Steinkopff Verlag, 1999) Jacomb, Trish; Jorm, Anthony F; Rodgers, Bryan; Korten, Ailsa; Henderson, A Scott; Christensen, Helen
    Following participation in a mental health survey of 2725 adults aged 18–79, respondents were asked if the questionnaire had made them feel distressed or depressed, and if it had been an intrusion on privacy or had made them feel good about themselves. While 5% reported feeling distressed, 3% depressed and 3% were concerned about privacy, 35% reported feeling good about themselves. The participants reporting negative feelings were more likely to be younger women, to be higher on negative personality measures, to report more anxiety and depression symptoms, and to have had more childhood adversity and lower social support. Those who reported positive feelings had higher positive personality scores, more social support and lower anxiety and depression. This group was more likely to be older women. Despite the sensitive nature of many of the questions, only a small percentage of respondents reported distress, while many found that the questionnaire had made them feel good about themselves. This is important information to present to Institutional Ethics Committees and to future participants in such studies
  • ItemEmbargo
    Age differences in depression and anxiety symptoms: A structural equation modelling analysis of data from a general population sample
    (Cambridge University Press, 1999) Christensen, Helen; Jorm, Anthony F; Mackinnon, Andrew; Korten, Ailsa; Jacomb, Trish; Rodgers, Bryan
    Background. There is debate as to whether the elderly are really at lower risk for depressive disorders, or whether endorsement of symptoms is artefactually low. The present paper assesses the effects of age on anxiety and depression, and examines whether age has direct effects on self-report of individual symptoms independent of its effect on the underlying dimensions of anxiety and depression. Methods. Structural equation modelling was used to assess the structure of the items and their associations with age and a number of demographic variables. The sample of 2622 participants aged between 18 and 79 years from Canberra (Australia) was drawn from the Electoral Roll. Two instruments were used: the anxiety and depression scales of Goldberg et al. (1988) and the Personal Disturbance Scale from the DSSI of Bedford et al. (1976). Results. Both scales were found to fit satisfactorily to a two factor model. Age correlated negatively with depression. After controlling for the effects of gender, marital status, education and financial difficulty, direct effects of age were found on items from both instruments, indicating that certain depression items were associated with a differential probability of endorsement in older people, even when the level of depression was equal to that of younger people. Items with direct age effects reflected physical (feeling slowed down; waking early) and psychological (hopeless about the future) components of depression. Direct effects of age on items from both anxiety scales were also found. Conclusions. The nature of the depression and anxiety experienced by younger and older people may differ qualitatively. Depression may be associated with an increase in somatic symptoms linked to physical changes and to an increase in endorsement of items which reflect the narrowing of opportunities in the long-term.
  • ItemEmbargo
    Marital status transitions and psychological distress: Longitudinal evidence from a national population sample
    (Cambridge University Press, 1999) Hope, Steven; Rodgers, Bryan; Power, Chris
    Background. Evidence is conflicting as to whether the association between marital status and psychological distress is due to selection (i.e. distress influences marital status) or causation (marital status influences distress). We investigate: (i) whether differences in psychological distress pre-date marital transitions; (ii) whether levels of distress change following transitions; and (iii) potential mediating and moderating factors. Methods. Data on psychological distress (indicated by the Malaise Inventory) and marital status at ages 23 and 33 were analysed for 4514 men and 4842 women from the 1958 birth cohort. Results. Higher levels of distress were found among the divorced and lower levels among the single and the married. Selection was seen in the lower initial mean symptoms of those who married (1·69 for men; 2·84 for women) compared to those remaining single (2·41 for men; 3·26 for women). Causation was indicated by the relative deterioration in distress of those who divorced compared to the continuously married (an increase of 0·31 and 0·03 respectively for men), especially in women (a decrease of 0·18 versus 0·71). This was most evident in women who were downwardly mobile and those with children. Recently separated men and women showed especially large increases in distress. Conclusions. The relationship between marital status and psychological distress involves selection and causation. Findings failed to support ideas of marriage being protective (through social support), or detrimental (through family roles). Divorce increased distress, with both acute and longer-term components moderated by secondary factors such as childcare and declining socio-economic status.
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