Patterning of tensile fabric structures with a discrete element model using dynamic relaxation

Tensile fabric membranes present opportunities for efficient structures, combining the cladding and support structure. Such structures must be doubly curved to resist external loads, but doubly curved surfaces cannot be formed from flat fabric without distorting. Computational methods of patterning are used to find the optimal composition of planar panels to generate the form, but are sensitive to the models and techniques used. This paper presents a detailed discussion of, and insights into, the computational process of patterning. A new patterning method is proposed, which uses a discrete model, advanced flattening methods, dynamic relaxation, and re-meshing to generate accurate cutting patterns. Comparisons are drawn with published methods of patterning to show the suitability of the method

Lethal Parasites in Oysters from Coastal Georgia with Discussion of Disease and Management Implications

Extensive mortalities of oysters, Crassostrea virginica, occurred from 1985 through 1987 in coastal waters of Georgia. Fluid thioglycolate cultures of oysters collected from 16 of 17 locations revealed infections by the apicomplexan parasite Perkinsus marinus. An ascetosporan parasite, Haplosporidium nelsoni, was also observed in histopathological examination of oysters from 4 of the locations. While the range of H. nelsoni currently is recognized as the east coast of the United States from Maine to Florida, this is the first report of the parasite in Georgia waters. This paper documents the occurrence of these two lethal parasites in oysters from coastal waters of Georgia, along with potential disease and management implications. Results of an earlier independent and previously unpublished survey are also discussed which document the presence of P. marinus in Georgia as early as 1966

Depression across pregnancy and the postpartum, antidepressant use and the association with female sexual function

Background: There is an established relationship between depression and sexual functioning in women. However, there is limited research examining the relationship between perinatal depression and sexual functioning. Methods: This study draws on the Mercy Pregnancy and Emotional Wellbeing Study and reports on 211 women recruited in early pregnancy and followed to 12 months postpartum. Women were assessed for depression using the Structured Clinical Interview for the DSM-IV, repeated measurement of depressive symptoms using the Edinburgh Postnatal Depression Scale and sexual functioning using the Female Sexual Functioning Inventory. Data were also collected on antidepressant use, mode of delivery, history of childhood trauma, breastfeeding and partner support. Results: Women showed a decline in sexual functioning over pregnancy and the first 6 months postpartum, which recovered by 12 months. For women with depression, sexual functioning was lower throughout pregnancy and continued to be lower at 6 months postpartum than those without depression. Ongoing depressive symptoms at 12 months were also associated with lower sexual functioning. Sexual functioning was not predicted by mode of delivery, antidepressant use or childhood trauma. Breastfeeding predicted lower sexual functioning only at 6 months. Higher partner support predicted higher female sexual functioning. Conclusions: Pregnancy and the postpartum are a time of reduced sexual functioning for women; however, women with depression are more likely to have lower levels of sexual functioning and this was not predicted by antidepressant use. In women with perinatal depression, consideration of the impact on sexual functioning should be an integral part of care

The role of trauma and partner support in perinatal depression and parenting stress: An Australian pregnancy cohort study

Background: Improving our understanding of the relationship between maternal depression and parenting stress is likely to lie in the range of additional factors that are associated with vulnerability to depression and also to parenting stress. Objectives: To examine the role of trauma and partner support, in understanding the relationship between perinatal depression and parenting stress. Methods: This study utilises data from 246 women in a pregnancy cohort study that followed women from early pregnancy until their infant was 12 months. Included were both women with a diagnosis of depression and those without depression. The measures included Structured Clinical Interview for the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, Edinburgh Postnatal Depression Scale, Childhood Trauma Questionnaire, Social Support Effectiveness Questionnaire and the Parenting Stress Index. Results: We found women with depression were more likely to report a history of childhood trauma. Depressive symptoms were positively associated with parenting stress while partner support was negatively associated with parenting stress. The protective role of partner support for parenting distress was observed in those with no history of childhood abuse and low depressive symptoms, but not in those with a trauma history and high depressive symptoms. Conclusions: These findings highlight the importance of early trauma in understanding the protective role of support on the relationship between parenting and depression. These findings can inform future studies and the refinement of future interventions aimed at both perinatal depression and parenting

Measuring the Size of Quasar Broad-Line Clouds Through Time Delay Light-Curve Anomalies of Gravitational Lenses

Intensive monitoring campaigns have recently attempted to measure the time delays between multiple images of gravitational lenses. Some of the resulting light-curves show puzzling low-level, rapid variability which is unique to individual images, superimposed on top of (and concurrent with) longer time-scale intrinsic quasar variations which repeat in all images. We demonstrate that both the amplitude and variability time-scale of the rapid light-curve anomalies, as well as the correlation observed between intrinsic and microlensed variability, are naturally explained by stellar microlensing of a smooth accretion disk which is occulted by optically-thick broad-line clouds. The rapid time-scale is caused by the high velocities of the clouds (~5x10^3 km/s), and the low amplitude results from the large number of clouds covering the magnified or demagnified parts of the disk. The observed amplitudes of variations in specific lenses implies that the number of broad-line clouds that cover ~10% of the quasar sky is ~10^5 per 4 pi steradian. This is comparable to the expected number of broad line clouds in models where the clouds originate from bloated stars.Comment: 19 pages, 9 figures. Submitted to Ap

A Simplified Instrument for Recording and Indicating Frequency and Intensity of Icing Conditions Encountered in Flight

An instrument for recording and indicating the frequency and intensity of aircraft icing conditions encountered in flight has been developed by the NACA Lewis Laboratory to obtain statistical icing data over world-wide air routes during routine airline operations. The operation of the instrument is based on the creation of a differential pressure between an ice-free total-pressure system and a total-pressure system in which small total-pressure holes vented to static pressure are allowed to plug with ice accretion. The simplicity of this operating principle permits automatic operation, and provides relative freedom from maintenance and operating problems. The complete unit weighing only 18 pounds records icing rate, airspeed, and altitude on photographic film and provides visual indications of icing intensity to the pilot

Antidepressant exposure in pregnancy and child sensorimotor and visuospatial development

Motor development underlies many aspects of education and learning. There has been uncertainty about the impact of exposure of antidepressant medication in pregnancy on child motor outcomes. This paper examines whether exposure to antidepressants in utero increases the risk of poorer motor development in two areas: sensorimotor and visuospatial processing. Data were obtained from 195 women and children across 3 groups: women with untreated depression in pregnancy, women treated with antidepressants and control women. Data were collected across pregnancy, postpartum and until 4 years for mother and child. Maternal depression was established at baseline with the Structured Clinical Interview for DSM-IV. Antidepressant exposure, including type, dose and timing, was measured through repeated self-report across pregnancy and the postpartum, medical records at delivery and in cord blood samples collected at delivery. Child sensorimotor and visuospatial outcomes were assessed at 4 years of age with four subtests from the NEPSY-II. Our study found for sensorimotor development, visuomotor precision completion time was associated with better performance for antidepressant exposed children compared to those with mothers with untreated depression. Yet another measure of sensorimotor development, motor manual sequences, was poorer in those exposed to antidepressants. One subtest for visuospatial processing, block construction, was associated with poorer performance in antidepressant-exposed children who had poor neonatal adaptation and those exposed to a higher dose of antidepressant. These findings suggest an inconsistent association between sensorimotor development and antidepressant use in pregnancy. However, the findings for visuospatial processing would support further exploration of antidepressant associated poor neonatal adaption and later motor development

Chimpanzees demonstrate individual differences in social information use

Studies of transmission biases in social learning have greatly informed our understanding of how behaviour patterns may diffuse through animal populations, yet within-species inter-individual variation in social information use has received little attention and remains poorly understood. We have addressed this question by examining individual performances across multiple experiments with the same population of primates. We compiled a dataset spanning 16 social learning studies (26 experimental conditions) carried out at the same study site over a 12-year period, incorporating a total of 167 chimpanzees. We applied a binary scoring system to code each participant’s performance in each study according to whether they demonstrated evidence of using social information from conspecifics to solve the experimental task or not (Social Information Score—‘SIS’). Bayesian binomial mixed effects models were then used to estimate the extent to which individual differences influenced SIS, together with any effects of sex, rearing history, age, prior involvement in research and task type on SIS. An estimate of repeatability found that approximately half of the variance in SIS was accounted for by individual identity, indicating that individual differences play a critical role in the social learning behaviour of chimpanzees. According to the model that best fit the data, females were, depending on their rearing history, 15–24% more likely to use social information to solve experimental tasks than males. However, there was no strong evidence of an effect of age or research experience, and pedigree records indicated that SIS was not a strongly heritable trait. Our study offers a novel, transferable method for the study of individual differences in social learning