Unsteady flow of a thixotropic fluid in a slowly varying pipe

We analyse the unsteady axisymmetric flow of a thixotropic or antithixotropic fluid in a slowly varying cylindrical pipe. We derive general perturbation solutions in regimes of small Deborah numbers, in which thixotropic or antithixotropic effects enter as perturbations to generalised Newtonian flow. We present results for the viscous Moore–Mewis–Wagner model and the viscoplastic Houška model, and we use these results to elucidate what can be predicted in general about the behaviour of thixotropic and antithixotropic fluids in lubrication flow. The range of behaviour we identify casts doubt on the efficacy of model reduction approaches that postulate a generic cross-pipe flow structure

Cortisol levels in response to starting school in children at increased risk for social phobia

Background: Research on depression has identified hyperactivity of the HPA axis as a potential contributory factor to the intergenerational transmission of affective symptoms. However, this has not yet been examined in the context of social phobia. The current study compared HPA axis activity in response to a universal social stressor (starting school) in children of 2 groups of women: one with social phobia and one with no history of anxiety (comparison group). To determine specificity of effects of maternal social phobia, a third group of children were also examined whose mothers had generalised anxiety disorder (GAD). Method: Children provided salivary cortisol samples in the morning, afternoon and at bedtime across 3 time-blocks surrounding the school start: a month before starting school (baseline), the first week at school (stress response), and the end of the first school term (stress recovery). Child behavioural inhibition at 14 months was also assessed to explore the influence of early temperament on later stress responses. Results: All children displayed an elevation in morning and afternoon cortisol from baseline during the first week at school, which remained elevated until the end of the first term. Children in the social phobia group, however, also displayed an equivalent elevation in bedtime cortisol, which was not observed for comparison children or for children of mothers with GAD. Children in the social phobia group who were classified as 'inhibited' at 14 months displayed significantly higher afternoon cortisol levels overall. Summary: A persistent stress response to school in the morning and afternoon is typical for all children, but children of mothers with social phobia also display atypical elevations in evening cortisol levels when at school - signalling long-term disruption of the circadian rhythm in HPA axis activity. This is the first study to report HPA axis disruption in children at risk of developing social phobia, and future research should aim to determine whether this represents a pathway for symptom development, taking early temperament into account

Thixotropic pumping in a cylindrical pipe

We consider the flow of a thixotropic fluid in a uniform cylindrical pipe, driven by an oscillating pressure gradient or a body force. For a variety of rheological models, solutions can be obtained by integrating ordinary rather than partial differential equations: we illustrate this approach for the thixo-viscoplastic Houška model and the thixo-viscous simplified Moore-Mewis-Wagner model. We present asymptotic results in the limits of small and large Deborah numbers, and numerical results for intermediate Deborah numbers. Under asymmetrical "sawtooth" forcing, thixotropy leads to the net transport of fluid along the pipe, even when there would be no net transport of the corresponding generalised-Newtonian fluid. We propose the name "thixotropic pumping" for this novel transport mechanism

On Dimensionality, Measurement Invariance, and Suitability of Sum Scores for the PHQ-9 and the GAD-7.

In psychiatry, severity of mental health conditions and their change over time are usually measured via sum scores of items on psychometric scales. However, inferences from such scores can be biased if psychometric properties such as unidimensionality and temporal measurement invariance for instruments are not met. Here, we aimed to evaluate these properties for common measures of depression (Patient Health Questionnaire-9) and anxiety (Generalized Anxiety Disorder Assessment-7) in a large clinical sample (N = 22,362) undergoing psychotherapy. In addition, we tested consistency in dimensionality results across different methods (parallel analysis, factor analysis, explained common variance, the partial credit model, and the Mokken model). Results showed that while both Patient Health Questionnaire-9 and Generalized Anxiety Disorder Assessment-7 are multidimensional instruments with highly correlated factors, there is justification for sum scores as measures of severity. Temporal measurement invariance across 10 therapy sessions was evaluated. Strict temporal measurement invariance was established in both scales, allowing researchers to compare sum scores as severity measures across time.NIH

Maternal psychological distress in primary care and association with child behavioural outcomes at age three

Observational studies indicate children whose mothers have poor mental health are at increased risk of socio-emotional behavioural difficulties, but it is unknown whether these outcomes vary by the mothers’ mental health recognition and treatment status. To examine this question, we analysed linked longitudinal primary care and research data from 1078 women enrolled in the Born in Bradford cohort. A latent class analysis of treatment status and self-reported distress broadly categorised women as (a) not having a common mental disorder (CMD) that persisted through pregnancy and the first 2 years after delivery (N = 756, 70.1 %), (b) treated for CMD (N = 67, 6.2 %), or (c) untreated (N = 255, 23.7 %). Compared to children of mothers without CMD, 3-year-old children with mothers classified as having untreated CMD had higher standardised factor scores on the Strengths and Difficulties Questionnaire (d = 0.32), as did children with mothers classified as having treated CMD (d = 0.27). Results were only slightly attenuated in adjusted analyses. Children of mothers with CMD may be at risk for socio-emotional and behavioural difficulties. The development of effective treatments for CMD needs to be balanced by greater attempts to identify and treat women. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1007/s00787-015-0777-2) contains supplementary material, which is available to authorized users

Adolescent Self-Organization and Adult Smoking and Drinking over Fifty Years of Follow-Up:The British 1946 Birth Cohort

Variations in markers of adolescent self-organization predict a range of economic and health-related outcomes in general population studies. Using a population-based birth cohort study we investigated associations between adolescent self-organization and two common factors over adulthood influencing health, smoking and alcohol consumption. The MRC National Survey of Health and Development (the British 1946 birth cohort) was used to test associations between a dimensional measure of adolescent self-organization derived from teacher ratings, and summary longitudinal measures of smoking and alcohol consumption over the ensuing five decades. Multinomial regression models were adjusted for sex, adolescent emotional and conduct problems, occupational social class of origin, childhood cognition, educational attainment and adult occupational social class. With all covariates adjusted, higher adolescent self-organization was associated with fewer smoking pack years, although not with quitting; there was no association with alcohol consumption across adulthood (none or heavy compared with light to moderate). Adolescent self-organization appears to be protective against smoking, but not against heavy alcohol consumption. Interpretation of this differential effect should be embedded in an understanding of the social and sociodemographic context in which these health behaviours occur over time

An Evaluation of the Precision of Measurement of Ryff’s Psychological Well-Being Scales in a Population Sample

The aim of this study is to assess the effective measurement range of Ryff’s Psychological Well-being scales (PWB). It applies normal ogive item response theory (IRT) methodology using factor analysis procedures for ordinal data based on a limited information estimation approach. The data come from a sample of 1,179 women participating in a midlife follow-up of a national birth cohort study in the UK. The PWB scales incorporate six dimensions: autonomy, positive relations with others, environmental mastery, personal growth, purpose in life and self-acceptance. Scale information functions were calculated to derive standard errors of measurement for estimated scores on each dimension. Construct variance was distinguished from method variance by inclusion of method factors from item wording (positive versus negative). Our IRT analysis revealed that the PWB measures well-being most accurately in the middle range of the score distribution, i.e. for women with average well-being. Score precision diminished at higher levels of well-being, and low well-being was measured more reliably than high well-being. A second-order well-being factor loaded by four of the dimensions achieved higher measurement precision and greater score accuracy across a wider range than any individual dimension. Future development of well-being scales should be designed to include items that are able to discriminate at high levels of well-being

Psychological distress during pregnancy in a multi-ethnic community: findings from the born in Bradford cohort study

Purpose: Antenatal anxiety and depression are predictive of future mental distress, which has negative effects on children. Ethnic minority women are more likely to have a lower socio-economic status (SES) but it is unclear whether SES is an independent risk factor for mental health in pregnancy. We described the association between maternal mental distress and socio-demographic factors in a multi-ethnic cohort located in an economically deprived city in the UK. Methods: We defined eight distinct ethno-language groups (total N = 8,454) and classified a threshold of distress as the 75th centile of within-group GHQ-28 scores, which we used as the outcome for univariate and multivariate logistic regression for each ethnic group and for the sample overall. Results: Financial concerns were strongly and independently associated with worse mental health for six out of the eight ethnic groups, and for the cohort overall. In some groups, factors such as working status, education and family structure were associated with worse mental health, but for others these factors were of little importance. Conclusions: The diversity between and within ethnic groups in this sample underlines the need to take into consideration individual social, migration and economic circumstances and their potential effect on mental health in ethnically diverse areas