Evolutionary and pulsational properties of white dwarf stars

Abridged. White dwarf stars are the final evolutionary stage of the vast majority of stars, including our Sun. The study of white dwarfs has potential applications to different fields of astrophysics. In particular, they can be used as independent reliable cosmic clocks, and can also provide valuable information about the fundamental parameters of a wide variety of stellar populations, like our Galaxy and open and globular clusters. In addition, the high densities and temperatures characterizing white dwarfs allow to use these stars as cosmic laboratories for studying physical processes under extreme conditions that cannot be achieved in terrestrial laboratories. They can be used to constrain fundamental properties of elementary particles such as axions and neutrinos, and to study problems related to the variation of fundamental constants. In this work, we review the essentials of the physics of white dwarf stars. Special emphasis is placed on the physical processes that lead to the formation of white dwarfs as well as on the different energy sources and processes responsible for chemical abundance changes that occur along their evolution. Moreover, in the course of their lives, white dwarfs cross different pulsational instability strips. The existence of these instability strips provides astronomers with an unique opportunity to peer into their internal structure that would otherwise remain hidden from observers. We will show that this allows to measure with unprecedented precision the stellar masses and to infer their envelope thicknesses, to probe the core chemical stratification, and to detect rotation rates and magnetic fields. Consequently, in this work, we also review the pulsational properties of white dwarfs and the most recent applications of white dwarf asteroseismology.Comment: 85 pages, 28 figures. To be published in The Astronomy and Astrophysics Revie

Endophytes vs tree pathogens and pests: can they be used as biological control agents to improve tree health?

Like all other plants, trees are vulnerable to attack by a multitude of pests and pathogens. Current control measures for many of these diseases are limited and relatively ineffective. Several methods, including the use of conventional synthetic agro-chemicals, are employed to reduce the impact of pests and diseases. However, because of mounting concerns about adverse effects on the environment and a variety of economic reasons, this limited management of tree diseases by chemical methods is losing ground. The use of biological control, as a more environmentally friendly alternative, is becoming increasingly popular in plant protection. This can include the deployment of soil inoculants and foliar sprays, but the increased knowledge of microbial ecology in the phytosphere, in particular phylloplane microbes and endophytes, has stimulated new thinking for biocontrol approaches. Endophytes are microbes that live within plant tissues. As such, they hold potential as biocontrol agents against plant diseases because they are able to colonize the same ecological niche favoured by many invading pathogens. However, the development and exploitation of endophytes as biocontrol agents will have to overcome numerous challenges. The optimization and improvement of strategies employed in endophyte research can contribute towards discovering effective and competent biocontrol agents. The impact of environment and plant genotype on selecting potentially beneficial and exploitable endophytes for biocontrol is poorly understood. How endophytes synergise or antagonise one another is also an important factor. This review focusses on recent research addressing the biocontrol of plant diseases and pests using endophytic fungi and bacteria, alongside the challenges and limitations encountered and how these can be overcome. We frame this review in the context of tree pests and diseases, since trees are arguably the most difficult plant species to study, work on and manage, yet they represent one of the most important organisms on Earth

Endophytes vs tree pathogens and pests: can they be used as biological control agents to improve tree health?

Like all other plants, trees are vulnerable to attack by a multitude of pests and pathogens. Current control measures for many of these diseases are limited and relatively ineffective. Several methods, including the use of conventional synthetic agro-chemicals, are employed to reduce the impact of pests and diseases. However, because of mounting concerns about adverse effects on the environment and a variety of economic reasons, this limited management of tree diseases by chemical methods is losing ground. The use of biological control, as a more environmentally friendly alternative, is becoming increasingly popular in plant protection. This can include the deployment of soil inoculants and foliar sprays, but the increased knowledge of microbial ecology in the phytosphere, in particular phylloplane microbes and endophytes, has stimulated new thinking for biocontrol approaches. Endophytes are microbes that live within plant tissues. As such, they hold potential as biocontrol agents against plant diseases because they are able to colonize the same ecological niche favoured by many invading pathogens. However, the development and exploitation of endophytes as biocontrol agents will have to overcome numerous challenges. The optimization and improvement of strategies employed in endophyte research can contribute towards discovering effective and competent biocontrol agents. The impact of environment and plant genotype on selecting potentially beneficial and exploitable endophytes for biocontrol is poorly understood. How endophytes synergise or antagonise one another is also an important factor. This review focusses on recent research addressing the biocontrol of plant diseases and pests using endophytic fungi and bacteria, alongside the challenges and limitations encountered and how these can be overcome. We frame this review in the context of tree pests and diseases, since trees are arguably the most difficult plant species to study, work on and manage, yet they represent one of the most important organisms on Earth

Radiation techniques for acromegaly

Radiotherapy (RT) remains an effective treatment in patients with acromegaly refractory to medical and/or surgical interventions, with durable tumor control and biochemical remission; however, there are still concerns about delayed biochemical effect and potential late toxicity of radiation treatment, especially high rates of hypopituitarism. Stereotactic radiotherapy has been developed as a more accurate technique of irradiation with more precise tumour localization and consequently a reduction in the volume of normal tissue, particularly the brain, irradiated to high radiation doses. Radiation can be delivered in a single fraction by stereotactic radiosurgery (SRS) or as fractionated stereotactic radiotherapy (FSRT) in which smaller doses are delivered over 5-6 weeks in 25-30 treatments. A review of the recent literature suggests that pituitary irradiation is an effective treatment for acromegaly. Stereotactic techniques for GH-secreting pituitary tumors are discussed with the aim to define the efficacy and potential adverse effects of each of these techniques

Acute Sleep Deprivation and Circadian Misalignment Associated with Transition onto the First Night of Work Impairs Visual Selective Attention

Background: Overnight operations pose a challenge because our circadian biology promotes sleepiness and dissipates wakefulness at night. Since the circadian effect on cognitive functions magnifies with increasing sleep pressure, cognitive deficits associated with night work are likely to be most acute with extended wakefulness, such as during the transition from a day shift to night shift. Methodology/Principal Findings: To test this hypothesis we measured selective attention (with visual search), vigilance (with Psychomotor Vigilance Task [PVT]) and alertness (with a visual analog scale) in a shift work simulation protocol, which included four day shifts followed by three night shifts. There was a nocturnal decline in cognitive processes, some of which were most pronounced on the first night shift. The nighttime decrease in visual search sensitivity was most pronounced on the first night compared with subsequent nights (p = .04), and this was accompanied by a trend towards selective attention becoming ‘fast and sloppy’. The nighttime increase in attentional lapses on the PVT was significantly greater on the first night compared to subsequent nights (p<.05) indicating an impaired ability to sustain focus. The nighttime decrease in subjective alertness was also greatest on the first night compared with subsequent nights (p<.05). Conclusions/Significance: These nocturnal deficits in attention and alertness offer some insight into why occupational errors, accidents, and injuries are pronounced during night work compared to day work. Examination of the nighttime vulnerabilities underlying the deployment of attention can be informative for the design of optimal work schedules and the implementation of effective countermeasures for performance deficits during night work

Positive parenting for healthy living (Triple P) for parents of children with type 1 diabetes: protocol of a randomised controlled trial

BACKGROUND: Type 1 diabetes is a serious, life-long condition which causes major health, social and economic burden for children, their families and the community. Diabetes management involves strict adherence to a complex regimen, and poor management and non-adherence are a persistent problem among children. Parent-child interactions and parenting have been identified as crucial points of intervention to support children’s health and emotional well-being, yet few parenting interventions have been developed or evaluated for parents of young children. This paper describes a randomised controlled trial of a brief, group-based parenting intervention for parents of young children (2-10 years) with type 1 diabetes compared against care as usual (CAU). METHODS/DESIGN: Families will be randomised to either Positive Parenting for Healthy Living Triple P or CAU. Positive Parenting for Healthy Living Triple P involves 2 × 2 h group sessions. Outcomes will be assessed via parent and child questionnaire, home observations and blood glucose monitoring at baseline, 1-month and 6-months post-intervention. Primary outcomes will be parent- and child-reported parenting behaviour, parent-reported child behaviour and adjustment, and parent-reported child quality-of-life. Secondary outcomes will include parental self-efficacy with diabetes management, illness-specific and general parenting stress, parent-reported child illness behaviour, family quality-of-life, observed parenting and child behaviour, and child’s illness control. DISCUSSION: The theoretical background, study hypotheses, methods and planned analyses are discussed. TRIAL REGISTRATION: Australian New Zealand Clinical Trials Registry: ACTRN12613001281785. Registered 20 November, 2013

Psychological adjustment and quality of life in children and adolescents following open-heart surgery for congenital heart disease: a systematic review

BACKGROUND: Children with congenital heart defects (CHD) requiring open-heart surgery are a group at high risk for health-related sequelae. Little consensus exists regarding their long-term psychological adjustment (PA) and health-related quality of life (QoL). Thus, we conducted a systematic review to determine the current knowledge on long-term outcome in this population. METHODS: We included randomized controlled trials, case control, or cohort studies published between 1990-2008 evaluating self- and proxy-reported PA and QoL in patients aged between two and 17 years with a follow-up of at least two years after open heart surgery for CHD. RESULTS: Twenty-three studies assessing psychological parameters and 12 studies assessing QoL were included. Methodological quality of the studies varied greatly with most studies showing a moderate quality. Results were as follows: (a) A considerable proportion of children experienced psychological maladjustment according to their parents; (b) studies on self-reported PA indicate a good outcome; (c) the studies on QoL suggest an impaired QoL for some children in particular for those with more severe cardiac disease; (d) parental reports of psychological maladjustment were related to severity of CHD and developmental delay. CONCLUSION: A significant proportion of survivors of open-heart surgery for CHD are at risk for psychological maladjustment and impaired QoL. Future research needs to focus on self-reports, QoL data and adolescents