30 resultados para Mixed-effect models
em Deakin Research Online - Australia
Resumo:
BACKGROUND: Studies have demonstrated usefulness of cognitive-behavioural therapy (CBT) in managing distress in inflammatory bowel disease (IBD); however, few have focused on IBD course. The present trial aimed to investigate whether adding CBT to standard treatment prolongs remission in IBD in comparison to standard therapy alone. METHODS: A 2-arm parallel pragmatic randomised controlled trial (+CBT - standard care plus either face-to-face (F2F) or online CBT over 10 weeks versus standard care alone (SC)) was conducted with adult patients in remission. IBD remission at 12 months since baseline was the primary outcome measure while the secondary outcome measures were mental health status and quality of life (QoL). Linear mixed-effect models were used to compare groups on outcome variables while controlling for baseline. RESULTS: Participants were 174 patients with IBD (90 +CBT, 84 SC). There was no difference in remission rates between groups, with similar numbers flaring at 12 months. Groups did not differ in anxiety, depression or coping at 6 or 12 months (p >0.05). When only participants classified as 'in need' (young, high baseline IBD activity, recently diagnosed; poor mental health) were examined in the post-hoc analysis (n = 74, 34 CBT and 40 controls), CBT significantly improved mental QoL (p = .034, d = .56) at 6 months. Online CBT group had a higher score on Precontemplation than the F2F group, which is consistent with less developed coping with IBD in the cCBT group (p = .045). CONCLUSIONS: Future studies should direct psychological interventions to patients 'in need' and attempt to recruit larger samples to compensate for significant attrition when using online CBT. TRIAL REGISTRATION: The protocol was registered on 21/10/2009 with the Australian New Zealand Clinical Trials Registry (ID: ACTRN12609000913279).
Seasonal- and sex-specific correlations between dispersal and exploratory behaviour in the great tit
Resumo:
While the importance of personality in explaining individual dispersal strategies is increasingly recognized, limited information is still available on how patterns of personality-dependent dispersal may develop, hampering our understanding of the ecological significance of behavioural dispersal syndromes. Here, we examine the relative importance of personality at different stages of dispersal in the great tit, by analysing the sex-specific relationship between exploratory behaviour (EB; quantified in a novel environment) and dispersal distances in different seasons over the course of the first year of life (summer, autumn, winter, and until the first breeding attempt). In females, we found that EB was an important predictor of dispersal distances in summer and autumn, but only a weak to moderate correlation remained for females captured in winter or for natal dispersal distances based on first breeding records. We obtained a contrasting pattern at the population level, whereby male (but not female) immigrants captured in summer and autumn had higher EB scores than locally born birds, while this was not the case in birds captured in winter and those recruited as breeders into the population. In addition to providing further evidence for the existence of a behaviour dispersal syndrome in birds, our results show that correlations between EB and dispersal appear strongest at the early stages of the dispersal process, rather than being developed gradually. These findings show the importance of analysing the effect of phenotypic attributes on dispersal across different stages of the dispersal phenomenon and in each sex separately.
Resumo:
Phenotypic variation and individual experience can create behavioural and/or dietary variation within a population. This may reduce intra-specific competition, creating a buffer to environmental change. This study examined how intrinsic variation affects foraging behaviour of Australian fur seals. Foraging movements of 29 female Australian fur seals were recorded using FastLoc GPS and dive behaviour recorders. For each individual, body mass, flipper length and axis length were recorded, a tooth was sampled to determine age, and milk was collected for diet analysis. Clustering of fatty acid dietary analysis revealed 5 distinct groups in the population. Behaviour was described using 19 indices, which were then reduced to 7 principal components (>80% of the behavioural variation). Bayesian mixed effect models were developed to describe the relationship between these components and intrinsic variation. No association was found between diet and age or body shape; however, age had a negative relationship with component 1 (27% of variation). Older females spent less time at-sea and foraged nearer to the colony. Age had an effect on component 5 (7% of variation), which represented haul-outs and dive depth; older females made fewer visits to haul-out sites and dived deeper to the benthos. This suggests that as animals age they are able to utilise prior knowledge to exploit nearby foraging sites that younger animals are either unaware of, or have yet to gain the experience required to efficiently utilise. Mass had a negative effect on components representing the directedness of a foraging trip, suggesting heavier individuals were more likely to travel directly to a foraging site.
Resumo:
Context : Designing an appropriate survey protocol requires understanding of how capture rates of target species may be influenced by factors other than on-ground abundance, such as weather conditions or seasonality. This is particularly relevant for ectotherms such as reptiles, as activity can be affected by environmental conditions such as ambient temperature.
Aims : The present study examines factors affecting capture success of reptiles in semi-arid environments of southern Australia, and addresses the following two main questions: (1) what is the influence of weather and seasonal factors on capture rates of reptiles, and (2) what are the implications for developing an effective protocol for reptile surveys?
Methods : We surveyed reptiles using pitfall traps in spring and summer of 2006/07 and 2007/08 at sites (n = 280) throughout the Murray Mallee region of south-eastern Australia. We used mixed-effect regression models to investigate the influence of seasonal and weather-related variables on species’ capture success.
Key results : Total captures of reptiles, and the likelihood of capture of 15 reptile species, increased with rising daily temperature. Greater numbers of individual species were captured during spring than in summer, even though temperatures were cooler. This probably reflects greater levels of activity associated with breeding. Several species were more likely to be captured when maximum or minimum daily temperatures exceeded a certain level (e.g. Lerista labialis, Delma australis, Nephrurus levis). Other factors, such as rainfall and moon phase, also influenced capture success of some species.
Conclusions : Surveys for reptiles in semi-arid environments are likely to capture the greatest diversity of species on warm days in late spring months, although surveys on hot days in summer will enhance detection of particular species (e.g. Morethia boulengeri, Varanus gouldii). We recommend trapping during periods with maximum temperatures exceeding 25–30C and minimum overnight temperatures of 15C. Finally, trapping during rainfall and full-moon events will maximise chances of encountering species sensitive to these variables (blind snakes and geckoes).
Implications : Selecting the most favourable seasonal and weather conditions will help ensure that reptile surveys maximise the likelihood of capturing the greatest diversity of reptiles, while minimising trap-effort required.
Resumo:
Human disturbances of wildlife, such as tourism, can alter the activities of targeted individuals. Repeated behavioural disruptions can have long-term consequences for individual vital rates (survival and reproduction). To manage these sub-lethal impacts, we need to understand how activity disruptions can influence bioenergetics and ultimately individual vital rates. Empirical studies of the mechanistic links between whale-watching boat exposure and behavioural variation and vital rates are currently lacking for baleen whales (mysticetes). We compared minke whale Balaenoptera acutorostrata behaviour on a feeding ground in the presence and absence of whale-watching boats. Effects on activity states were inferred from changes in movement metric data as well as the occurrence of surface feeding events. Linear mixed effects models and generalised estimation equations were used to investigate the effect of whale-watching boat interactions. Measurement errors were quantified, and their effects on model parameter estimates were investigated using resampling methods. Minke whales responded to whale-watching boats by performing shorter dives and increased sinuous movement. A reduction in the probability of observing longer inter-breath intervals during sinuous movement showed that whale-watching boat interactions reduced foraging activity. Further, the probability of observing surface feeding events also decreased during interactions with whale-watching boats. This indicates that whalewatching boats disrupted the feeding activities of minke whales. Since minke whales are capital breeders, a decrease in feeding success on the feeding grounds due to whale-watching boats could lead to a decrease in energy available for foetus development and nursing on the breeding grounds. Such impact could therefore alter the calving success of this species.
Resumo:
Research significance: Job insecurity, the subjective individual anticipation of involuntary job loss, negatively affects employees’ health and their engagement. Although the relationship between job insecurity and health has been extensively studied, job insecurity as an ‘exposure’ has received far less attention, with little known about the upstream determinants of job insecurity in particular. This research sought to identify the relationship between self-rated job insecurity and area-level unemployment using a longitudinal, nationally representative study of Australian households. Methods: Mixed-effect multi-level regression models were used to assess the relationship between area-based unemployment rates and self-reported job insecurity using data from a longitudinal, nationally representative survey running since 2001. Interaction terms were included to test the hypotheses that the relationship between area-level unemployment and job insecurity differed between occupational skill-level groups and by employment arrangement. Marginal effects were computed to visually depict differences in job insecurity across areas with different levels of unemployment. Results: Results indicated that areas with the lowest unemployment rates had significantly lower job insecurity (predicted value 2.74; 95% confidence interval (CI) 2.71–2.78, P < 0.001) than areas with higher unemployment (predicted value 2.81; 95% CI 2.79–2.84, P < 0.001). There was a stronger relationship between area-level unemployment and job insecurity among precariously and fixed-term employed workers than permanent workers. Conclusion: These findings demonstrate the independent influences of prevailing economic conditions, individual- and job-level factors on job insecurity. Persons working on a casual basis or on a fixed-term contract in areas with higher levels of unemployment are more susceptible to feelings of job insecurity than those working permanently.
Resumo:
Artisanal fisheries are a key source of food and income for millions of people, but if poorly managed, fishing can have declining returns as well as impacts on biodiversity. Management interventions such as spatial and temporal closures can improve fishery sustainability and reduce environmental degradation, but may carry substantial short-term costs for fishers. The Lake Alaotra wetland in Madagascar supports a commercially important artisanal fishery and provides habitat for a Critically Endangered primate and other endemic wildlife of conservation importance. Using detailed data from more than 1,600 fisher catches, we used linear mixed effects models to explore and quantify relationships between catch weight, effort, and spatial and temporal restrictions to identify drivers of fisher behaviour and quantify the potential effect of fishing restrictions on catch. We found that restricted area interventions and fishery closures would generate direct short-term costs through reduced catch and income, and these costs vary between groups of fishers using different gear. Our results show that conservation interventions can have uneven impacts on local people with different fishing strategies. This information can be used to formulate management strategies that minimise the adverse impacts of interventions, increase local support and compliance, and therefore maximise conservation effectiveness.
Resumo:
The aim of this study was to identify within-season differences in basketball players' game-related statistics according to team quality and playing time. The sample comprised 5309 records from 198 players in the Spanish professional basketball league (2007-2008). Factor analysis with principal components was applied to the game-related statistics gathered from the official box-scores, which limited the analysis to five factors (free-throws, 2-point field-goals, 3-point field-goals, passes, and errors) and two variables (defensive and offensive rebounds). A two-step cluster analysis classified the teams as stronger (69 ± 8 winning percentage), intermediate (43 ± 5 winning percentage), and weaker teams (32 ± 5 winning percentage); individual players were classified based on playing time as important players (28 ± 4 min) or less important players (16 ± 4 min). Seasonal variation was analysed monthly in eight periods. A mixed linear model was applied to identify the effects of team quality and playing time within the months of the season on the previously identified factors and game-related statistics. No significant effect of season period was observed. A team quality effect was identified, with stronger teams being superior in terms of 2-point field-goals and passes. The weaker teams were the worst at defensive rebounding (stronger teams: 0.17 ± 0.05; intermediate teams: 0.17 ± 0.06; weaker teams: 0.15 ± 0.03; P = 0.001). While playing time was significant in almost all variables, errors were the most important factor when contrasting important and less important players, with fewer errors being made by important players. The trends identified can help coaches and players to create performance profiles according to team quality and playing time. However, these performance profiles appear to be independent of season period.
Resumo:
BACKGROUND AND AIMS: Previous studies have shown that antidepressants reduce inflammation in animal models of colitis. The present trial aimed to examine whether fluoxetine added to standard therapy for Crohn's disease [CD] maintained remission, improved quality of life [QoL] and/or mental health in people with CD as compared to placebo. METHODS: A parallel randomized double-blind placebo controlled trial was conducted. Participants with clinically established CD, with quiescent or only mild disease, were randomly assigned to receive either fluoxetine 20 mg daily or placebo, and followed for 12 months. Participants provided blood and stool samples and completed mental health and QoL questionnaires. Immune functions were assessed by stimulated cytokine secretion [CD3/CD28 stimulation] and flow cytometry for cell type. Linear mixed-effects models were used to compare groups. RESULTS: Of the 26 participants, 14 were randomized to receive fluoxetine and 12 to placebo. Overall, 14 [54%] participants were male. The mean age was 37.4 [SD=13.2] years. Fluoxetine had no effect on inflammatory bowel disease activity measured using either the Crohn's Disease Activity Index [F(3, 27.5)=0.064, p=0.978] or faecal calprotectin [F(3, 32.5)=1.08, p=0.371], but did have modest effects on immune function. There was no effect of fluoxetine on physical, psychological, social or environmental QoL, anxiety or depressive symptoms as compared to placebo [all p>0.05]. CONCLUSIONS: In this small pilot clinical trial, fluoxetine was not superior to placebo in maintaining remission or improving QoL. [ID: ACTRN12612001067864.].
Resumo:
Background: Much evidence has accumulated over the last three decades that low social support is related to both mental and physical health. Despite this large and convincing literature, reviewers have noted that there exists remarkably little evidence that social support can be increased by an appropriate intervention. This study reports on the development and evaluation of a new intervention for social support which takes account of the stress-buffering and direct effect models.
Method: Eighty-one individuals scoring low on social support were randomly allocated to the intervention or a waiting-list control condition. Treatment consisted of 10 weekly sessions administered in a group format, and 49 participants (nine males) completed assessments at the beginning and end of a 10-week period, and at 10-week follow-up (intervention condition only).
Results: The intervention proved to be successful at increasing functional support but not structural support. The intervention was also successful in increasing the social skill of self-disclosure, and decreasing depression. Gains made between pre- and post-treatment were maintained at 10-week follow-up.
Conclusions: Based on published analyses of the effects of social support on health, the results imply that the intervention would be useful for stress-buffering purposes, but not for the general health-promoting effects that are associated with good social integration.
Resumo:
Objectives: The relationship between actual and perceived object control competence (ball skills) and the contribution to young children’s physical activity is not known.
Design: Cross sectional study.
Methods: The Test Gross Motor Development-2 assessed actual object control competence and a modified version of the Pictorial Scale of Perceived Competence and Social Acceptance for Young Children assessed perceived object control competence. Moderate- to vigorous-intensity physical activity was measured via accelerometry. Three mixed regression models were performed: (i) object control competence as the predictor and the outcome as perceived object control, (ii) perceived object control competence as the predictor and the outcome moderate to vigorous physical activity and (iii) actual object control as the predictor and the outcome moderate to vigorous physical activity. Models adjusted for school clustering, monitor wear time, sex and age. Interactions between respective predictor variables and sex were performed if warranted. A total of 102 children (56% boys, 44% girls) aged 4–8 years (M 6.3, SD 0.92) completed assessments.
Results: Girls had lower perceived and actual object control competence and were less active than boys. Actual object control competence was positively associated with perceived object control competence (B = 0.11, t(96) = 2.25, p < 0.001, p = 0.027) and this relationship did not differ by sex (p = 0.449); however, neither actual (p = 0.092) nor perceived object control competence (p = 0.827) were associated with moderate to vigorous physical activity.
Discussion: Young children’s perceived ball skill abilities appear to relate to actual competence; however, these measures were not associated with physical activity. In older children, object control skill is associated with physical activity so targeting young children’s object control skills is an intervention priority.
Resumo:
PURPOSE: Thousands of children are living with advanced cancer; yet patient-reported outcomes (PROs) have rarely been used to describe their experiences. We aimed to describe symptom distress in 104 children age 2 years or older with advanced cancer enrolled onto the Pediatric Quality of Life and Evaluation of Symptoms Technology (PediQUEST) Study (multisite clinical trial evaluating an electronic PRO system).
METHODS: Symptom data were collected using age- and respondent-adapted versions of the PediQUEST Memorial Symptom Assessment Scale (PQ-MSAS) at most once per week. Clinical and treatment data were obtained from medical records. Individual symptom scores were dichotomized into high/low distress. Determinants of PQ-MSAS scores were explored using linear mixed-effects models.
RESULTS: During 9 months of follow-up, PQ-MSAS was administered 920 times: 459 times in teens (99% self-report), 249 times in children ages 7 to 12 years (96% child/parent report), and 212 times in those ages 2 to 6 years (parent reports). Common symptoms included pain (48%), fatigue (46%), drowsiness (39%), and irritability (37%); most scores indicated high distress. Among the 73 PQ-MSAS surveys administered in the last 12 weeks of life, pain was highly prevalent (62%; 58% with high distress). Being female, having a brain tumor, experiencing recent disease progression, and receiving moderate- or high-intensity cancer-directed therapy in the prior 10 days were associated with worse PQ-MSAS scores. In the final 12 weeks of life, receiving mild cancer-directed therapy was associated with improved psychological PQ-MSAS scores.
CONCLUSION: Children with advanced cancer experience high symptom distress. Strategies to promote intensive symptom management are indicated, especially with disease progression or administration of intensive treatments.
Resumo:
BACKGROUND: Treatment strategies for mental disorders may vary according to illness stage. However no data currently exist to guide treatment in first episode psychotic mania. The aim of this study was to compare the safety and efficacy profile of chlorpromazine and olanzapine, as add-on to lithium, in patients with a first episode of psychotic mania, expecting better safety profile and adherence to olanzapine but similar efficacy for both treatments. METHODS: Data from 83 patients were collected in an 8-week randomised controlled trial on clinical variables, side effects, vital signs, and weight. Analyses of treatment differences over time were based on intent-to-treat principles. Kaplan-Meier estimated survival curves were used to analyse time-to-event data and mixed effects models repeated measures analysis of variance were used to determine treatment group differences over time on safety and efficacy measures. RESULTS: Ethics committee approval to delay informed consent procedure until recovery from the acute episode allowed the inclusion of 83 patients highly representative of those treated in the public sector. Contrary to our hypotheses, safety profile of both medications was similar. A signal for higher rate (P=.032) and earlier occurrence (P=.043) of mania remission was observed in the olanzapine group which did not survive correction for multiple comparisons. CONCLUSIONS: Olanzapine and chlorpromazine have a similar safety profile in a uniquely representative cohort of patients with first episode psychotic mania. The possibility for a greater impact of olanzapine on manic symptoms leading to earlier remission of the episode needs exploration in a large sample.
Resumo:
This study explores the longitudinal effect of adolescent volunteering behaviour on young adult volunteering and the completion of secondary school. Utilising data from the Australian sample of the International Youth Development Study, frequency of volunteering in Grade 9 (mean age = 15 years) and in young adulthood (mean age = 21 years), and completion of secondary school were measured. Mixed effect logistic regression analyses revealed that adolescent volunteering was associated with an increased likelihood of volunteering in young adulthood (Odds Ratio [OR] 1.29; 95% Confidence Interval [CI] 1.20–1.39; N = 2,648) and of Grade 12 completion (OR 1.14; CI 1.03–1.28; N = 2,648), after controlling for family socioeconomic status and adolescent school adjustment. These findings suggest that adolescent volunteering may lead to further involvement in young adult volunteering and have a positive effect on school completion.
Resumo:
In this study, we have investigated the evidence of fetal heart rate asymmetry and how the fetal heart rate asymmetry changes before and after 35 weeks of gestation. Noninvasive fetal electrocardiogram (fECG) signals from 45 pregnant women at the gestational age from16 to 41 weeks with normal single pregnancies were analysed. A nonlinear parameter called heart rate asymmetry (HRA) index that measures time asymmetry of RR interval time-series signal was used to understand the changes of HRA in early and late fetus groups. Results indicate that fetal HRA measured by Porta's Index (PI) consistently increases after 35 weeks gestation compared to foetus before 32 weeks of gestation. It might be due to significant changes of sympatho-vagal balance towards delivery with more sympathetic surge. On the other hand, Guzik's Index (GI) showed a mixed effect i.e., increases at lower lags and decreases at higher lags. Finally, fHRA could potentially help identify normal and the pathological autonomic nervous system development.