164 research outputs found
Growing biserrula to improve grain and livestock production
Biserrula pelecinus is a new genus of pasture legume which was developed for commercial agriculture by a team of Perth-based legume pasture scientists in the early 1990s. Biserrula is an annual pasture legume that is found in natural grasslands of the Mediterranean Basin, frequently on acidic soils derived from granite. It was this feature that first caught the eye of researchers who were attempting to develop species that could tolerate the soil stresses of acidity and low moisture-holding capacity. These stresses are common in WA and when they occur together they are problematical for the survival of annual medics and clovers.Biserrula has subsequently been shown to possess a number of important features that give it advantages over the traditional pasture species in mixed farming systems.https://researchlibrary.agric.wa.gov.au/bulletins/1213/thumbnail.jp
Simulating Self-gravitating Hydrodynamic Flows
An efficient algorithm for solving Poisson's equation in two and three
spatial dimensions is discussed. The algorithm, which is described in detail,
is based on the integral form of Poisson's equation and utilizes spherical
coordinates and an expansion into spherical harmonics. The solver can be
applied to and works well for all problems for which the use of spherical
coordinates is appropriate. We also briefly discuss the implementation of the
algorithm into hydrodynamic codes which are based on a conservative
finite--difference scheme.Comment: 15 pages, compressed uu-encoded postscript file (232kB), to appear in
Computer Physics Communications, special issue Computational Hydrodynamics in
Astrophysic
Environmental variables affecting small‐scale distributions of five rotifer species in Lancaster Lake, Michigan
The small‐scale distributions of the rotifers Polyarthra vulgaris, Synchaeta stylata, Conochilus unicornis, Hexarthra mira , and Asplanchna priodonta were investigated in Lancaster Lake, Cheboygan County, Michigan, July 21, 1974. Measurements were taken for 13 depths (at 1‐m intervals) and at 4 times of the day (1:00 AM, 7:00 AM, 1:00 PM, and 7:00 PM). In addition, the abundances of 6 crustacean, 2 planktonic dipteran, and 10 algal species, as well as temperature, light, oxygen, chlorophyll a , alkalinity, pH and free carbon dioxide were measured. Whereas abiotic factors appeared to control large scale occupation of the lake, and excluded most species from the deeper portions of the hypolimnion, small‐scale distributional variation of the rotifers depended upon biotic interactions, particularly with the crustacean zooplankton.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/90242/1/3510620404_ftp.pd
Recurrent short sleep, chronic insomnia symptoms and salivary cortisol: A 10-year follow-up in the Whitehall II study
Although an association between both sleep duration and disturbance with salivary cortisol has been suggested, little is known about the long term effects of poor quality sleep on diurnal cortisol rhythm. The aim of this study was to examine the association of poor quality sleep, categorised as recurrent short sleep duration and chronic insomnia symptoms, with the diurnal release of cortisol. We examined this in 3314 participants from an occupational cohort, originally recruited in 1985-1989. Salivary cortisol was measured in 2007-2009 and six saliva samples were collected: (1) waking, (2) waking + 0.5 h, (3) +2.5 h, (4) +8 h, (5) +12 h and (6) bedtime, for assessment of the cortisol awakening response and the diurnal slope in cortisol secretion. Participants with the first saliva sample collected within 15 min of waking and not on steroid medication were examined. Short sleep duration (≤5 h) and insomnia symptoms (Jenkins scale, highest quartile) were measured in 1997-1999, 2003-2004 and 2007-2009. Recurrent short sleep was associated with a flatter diurnal cortisol pattern. A steeper morning rise in cortisol was observed among those reporting chronic insomnia symptoms at three time points and among those reporting short sleep twice, compared to those who never reported sleep problems. Participants reporting short sleep on three occasions had higher levels of cortisol later in the day, compared to those never reporting short sleep, indicated by a positive interaction with hours since waking (β = 0.02 (95% CI: 0.01, 0.03)). We conclude that recurrent sleep problems are associated with adverse salivary cortisol patterns throughout the day
Cortisol Awakening Response and Nighttime Salivary Cortisol Levels in Healthy Working Korean Subjects
∙ The authors have no financial conflicts of interest. Purpose: Cortisol awakening response (CAR) and nighttime cortisol levels have been used as indices of adrenocortical activity. However, population-based statistical information regarding these indices has not been provided in healthy subjects. This study was carried out to provide basic statistical information regarding these indices. Materials and Methods: Cortisol levels were measured in saliva samples collected immediately upon awakening (0 min), 30 min after awakening and in the nighttime on two consecutive days in 133 healthy subjects. Results: We determined the mean [standard deviation (SD)], median (interquartile range) and 5th-95th percentile range for each measure and auxiliary indices for CAR, i.e., the secreted cortisol concentration within 30 min of awakening (CARscc) and absolute and relative increases in cortisol level within 30 min of awakening (CARi and CARi%, respectively). We also determined these values for auxiliary indices derived from nighttime cortisol level, i.e., the ratio of cortisol level 30 min afte
Infant Developmental Outcomes: A Family Systems Perspective
The aim of the current study was to examine whether parental mental health, parent–infant relationship, infant characteristics and couple's relationship factors were associated with the infant's development. Forty-two families took part at three time points. The first, at 3 months postpartum, involved a video recorded observation (CARE-index) of parent–infant interactions. At 5 months postpartum, in-depth clinical interviews (the Birmingham Interview of Maternal Mental Health) assessed parental mental health and parental perceptions of their relationship with their infant, their partner and their infant's characteristics. Finally, the Bayley Scales III was carried out 17 months postpartum to assess the infants' cognitive, language and motor development. A higher mother–infant relationship quality was significantly associated with more optimal language development, whilst a higher father–infant relationship quality was associated with more advanced motor development. Additionally, maternal postnatal post-traumatic stress disorder had a negative impact on the infant's cognitive development, whilst maternal prenatal depression was associated with a less optimal infant's language development. The largest prediction was afforded by parental perceptions of their infant's characteristics. The findings indicate that such perceptions may be crucial for the infant's development and imply that negative internal parental perceptions should be considered when assessing risk factors or designing interventions to prevent negative child outcomes
Self-perceived stress reactivity is an indicator of psychosocial impairment at the workplace
BACKGROUND: Work related stress is associated with a range of debilitating health outcomes. However, no unanimously accepted assessment tool exists for the early identification of individuals suffering from chronic job stress. The psychological concept of self-perceived stress reactivity refers to the individual disposition of a person to answer stressors with immediate as well as long lasting stress reactions, and it could be a valid indicator of current as well as prospective adverse health outcomes. The aim of this study was to determine the extent to which perceived stress reactivity correlates with various parameters of psychosocial health, cardiovascular risk factors, and parameters of chronic stress and job stress in a sample of middle-aged industrial employees in a so-called "sandwich-position". METHODS: In this cross-sectional study, a total of 174 industrial employees were assessed for psychosocial and biological stress parameters. Differences between groups with high and low stress reactivity were analysed. Logistic regression models were applied to identify which parameters allow to predict perceived high versus low stress reactivity. RESULTS: In our sample various parameters of psychosocial stress like chronic stress and effort-reward imbalance were significantly increased in comparison to the normal population. Compared to employees with perceived low stress reactivity, those with perceived high stress reactivity showed poorer results in health-related complaints, depression, anxiety, sports behaviour, chronic stress, and effort-reward imbalance. The educational status of employees with perceived low stress reactivity is higher. Education, cardiovascular complaints, chronic stress, and effort-reward imbalance were moderate predictors for perceived stress reactivity. However, no relationship was found between stress reactivity and cardiovascular risk factors in our sample. CONCLUSIONS: Job stress is a major burden in a relevant subgroup of industrial employees in a middle management position. Self-perceived stress reactivity seems to be an appropriate concept to identify employees who experience psychosocial stress and associated psychological problems at the workplace
Epigenetic and Genetic Factors Predict Women's Salivary Cortisol following a Threat to the Social Self
10.1371/journal.pone.0048597PLoS ONE711
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