258 research outputs found
Erratum to âOn the effects of internal heat sources upon forced convection in porous channels with asymmetric thick wallsâ [Int. Comm. Heat Mass Trans. 73 (2016) 100â110]
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The Breeding Biology and Habitat Relationships of the Yellowhead
This study aimed to find an explanation for the decline of yellowheads and formulate
recommendations for management and further research on the species. There were
three main lines of investigation: basic population ecology and behaviour; the effect of
introduced predators on breeding; and the habitat relationships of the species. A
detailed study of a yellowhead population in the Eglinton Valley in Fiordland National
Park was undertaken. Birds were caught and banded and their behaviour, breeding and
survival monitored for 4 years. The relationship between yellowhead distribution and
vegetation, topography, and fertility were investigated in part of Mt Aspiring National
Park during one summer.
Yellowheads suffered high rates of predation from stoats during "plagues" that occurred
after heavy beech seeding. Three aspects of yellowhead biology made them vulnerable
to mammalian predation: (1) they nested in holes and predators killed not only eggs and
nestlings, but also incubating adults; (2) only the females incubated, thus losses to
predators had a greater effect on the population than if equal numbers of males and
females were killed; and (3) yellowheads nested later than most other forest passerines
and were still nesting when stoat numbers reached their summer peak. Though the
yellowhead's hole nesting habit made them vulnerable to mammals it restricted nest
parasitism and predation by long-tailed cuckoos and hole nesting is likely to have
evolved in response to cuckoos.
Yellowheads were found to be tall forest specialists; they occurred more frequently in
tall forests than short ones, and preferentially used the largest trees. Their choice of nest
sites had no effect on their preference for any forest types. The forests they favoured
grew mainly on fertile valley floors at low altitudes.
Yellowhead populations in "good habitats" raised two broods a year and these
populations are probably sufficiently productive to withstand stoat plagues occurring
once every 5 years, the average frequency of this event. Populations in "poor habitats"
raise only one brood and their productivity is probably insufficient to match losses to
stoats. Such populations are probably slowly declining, and are very vulnerable to
extinction.
A habitat suitability index was devised and forests in the north of the South Island from
which yellowheads have disappeared, were compared with those in the south where
yellowheads persist. Northern forests were as good for yellowheads as southern ones.
Thus, the combination of habitat preference and predation cannot account for the recent
disappearance of yellowheads from the northern half of the South Island.
The decline in yellowheads was attributed to both predation by introduced mammals
and competition with introduced vespulid wasps. Predation may have eliminated
yellowheads from podocarp-dominated forests where predator numbers are constantly
high, but they survive in some beech forests where predator numbers rise only once
every five years. However, even within beech forests only the most productive
populations are sufficiently productive to survive predation and these populations are
probably susceptible to competition with wasps which eat large numbers of
invertebrates.
Yellowheads are likely to be more vulnerable to wasp competition than other forest
insectivores because: (1) predation has reduced their productivity more than other birds
because they nest in holes; (2) they are specialised in low altitude, tall forest that the
wasps also favour; (3) their breeding is later than most other forest birds and their
period of juvenile dependence much longer. Yellowheads are still feeding fledgling
yellowheads at the time when wasps numbers reach their peak in the autumn, whereas
the offspring of other forest birds are independent by this stage
Assessment of recycled glass and expanded clay in a dual media configuration for drinking water treatment
Self-management of coronary heart disease in older patients after elective percutaneous transluminal coronary angioplasty
Objective To explore how older patients self-manage their coronary heart disease (CHD) after undergoing elective percutaneous transluminal coronary angioplasty (PTCA).Methods This mixed methods study used a sequential, explanatory design and recruited a convenience sample of patients (n = 93) approximately three months after elective PTCA. The study was conducted in two phases. Quantitative data collected in Phase 1 by means of a self-administered survey were subject to univariate and bivariate analysis. Phase 1 findings informed the purposive sampling for Phase 2 where ten participants were selected from the original sample for an in-depth interview. Qualitative data were analysed using thematic analysis. This paper will primarily report the findings from a sub-group of older participants (n = 47) classified as 65 years of age or older.Results 78.7% (n = 37) of participants indicated that they would manage recurring angina symptoms by taking glyceryl trinitrate and 34% (n = 16) thought that resting would help. Regardless of the duration or severity of the symptoms 40.5% (n = 19) would call their general practitioner or an emergency ambulance for assistance during any recurrence of angina symptoms. Older participants weighed less (P = 0.02) and smoked less (P = 0.01) than their younger counterparts in the study. Age did not seem to affect PTCA patientsâ likelihood of altering dietary factors such as fruit, vegetable and saturated fat consumption (P = 0.237).Conclusions The findings suggest that older people in the study were less likely to know how to correctly manage any recurring angina symptoms than their younger counterparts but they had fewer risk factors for CHD. Age was not a factor that influenced participantsâ likelihood to alter lifestyle factors
The development of theory-informed participant-centred interventions to maximise participant retention in randomised controlled trials
Acknowledgements We would like to thank all of the participants who volunteered their time to contribute to this study. We would also like to thank all of the teams linked to the host trials we worked with to help identify potential participants. Funding This research is funded by the Chief Scientist Office of the Scottish Governmentâs Health and Social Care Department [HIPS/16/46]. KG held a Medical Research Council UK Methodology Fellowship during the delivery of this project [MR/L01193X/1]. The publication was supported through a Health Research Board Trials Methodology Research Network award. MDW acknowledges support from the NIHR Newcastle Biomedical Research Centre. MW acknowledges support from the NIHR Imperial Biomedical Research Centre (BRC). The Health Services Research Unit, Institute of Applied Health Sciences (University of Aberdeen), is core-funded by the Chief Scientist Office of the Scottish Government Health and Social Care Directorates. The funders had no involvement in study design, collection, analysis and interpretation of data, reporting or the decision to publish.Peer reviewedPublisher PD
Where do you go when your periods go?: A case-study examining secondary amenorrhea in a professional internationally-capped female soccer player through the lens of the sport nutritionist
This case study follows a professional internationally capped female soccer player's two-year journey from eumenorrhea, through injury, to amenorrhea, and the challenges faced by the player and nutritionist. The two years are split into three sections: (1) longitudinal profiling of the player, (2) nutrition to support her return from injury, and (3) investigation into the observed secondary amenorrhea. The cause of amenorrhea was investigated through the assessment of energy availability via doubly labelled water, remote food photography, blood biomarkers and resting metabolic rate. Despite having secondary amenorrhea and anovulatory cycles, the player did not have low energy availability. This study shows the importance for practitioner's, particularly nutritionists, to not assume that all menstrual irregularities are caused by low energy availability and could be caused by a combination of factors (e.g. clinical, physiological, and psychological), which requires a multi-disciplinary investigation and intervention team. This study also showed that education needs to be provided about menstrual health to elite female soccer players as the player (i) believed that not having a period was beneficial for performance and unsure of possible health implications; (ii) was convinced that a one-day bleed indicated a regular menstrual cycle; and (iii) was reluctant to waste the practitioners time discussing menstrual issues and was nervous of finding out if she had an actual health issue. It is therefore crucial that players feel comfortable in discussing their menstrual status with practitioners to support their performance and long-term health
Sexuality generates diversity in the Aflatoxin Gene cluster: evidence on a global scale
Aflatoxins are produced by Aspergillus flavus and A. parasiticus in oil-rich seed and grain crops and are a serious problem in agriculture, with aflatoxin B1 being the most carcinogenic natural compound known. Sexual reproduction in these species occurs between individuals belonging to different vegetative compatibility groups (VCGs). We examined natural genetic variation in 758 isolates of A. flavus, A. parasiticus and A. minisclerotigenes sampled from single peanut fields in the United States (Georgia), Africa (Benin), Argentina (CoÂŽrdoba), Australia (Queensland) and India (Karnataka). Analysis of DNA sequence variation across multiple intergenic regions in the aflatoxin gene clusters of A. flavus, A. parasiticus and A. minisclerotigenes revealed significant linkage disequilibrium (LD) organized into distinct blocks that are conserved across different localities, suggesting that genetic recombination is nonrandom and a global occurrence. To assess the contributions of asexual and sexual reproduction to fixation and maintenance of toxin chemotype diversity in populations from each locality/species, we tested the null hypothesis of an equal number of MAT1-1 and MAT1-2 mating-type individuals, which is indicative of a sexually recombining population. All samples were clone-corrected using multi-locus sequence typing which associates closely with VCG. For both A. flavus and A. parasiticus, when the proportions of MAT1-1 and MAT1-2 were significantly different, there was more extensive LD in the aflatoxin cluster and populations were fixed for specific toxin chemotype classes, either the non-aflatoxigenic class in A. flavus or the B1-dominant and G1-dominant classes in A. parasiticus. A mating type ratio close to 1:1 in A. flavus, A. parasiticus and A. minisclerotigenes was associated with higher recombination rates in the aflatoxin cluster and less pronounced chemotype differences in populations. This work shows that the reproductive nature of the population (more sexual versus more asexual) is predictive of aflatoxin chemotype diversity in these agriculturally important fungi.Fil: Moore, Geromy G.. United States Department of Agriculture; Estados UnidosFil: Elliott, Jacalyn L.. University Of North Carolina; Estados UnidosFil: Singh, Rakhi. University Of North Carolina; Estados UnidosFil: Horn, Bruce W.. United States Department Of Agriculture; Estados UnidosFil: Dorner, Jeo W.. United States Department Of Agriculture; Estados UnidosFil: Stone, Eric A.. University Of North Carolina; Estados UnidosFil: Chulze, Sofia Noemi. Universidad Nacional de RĂo Cuarto. Facultad de Ciencias Exactas, FisicoquĂmicas y Naturales. Departamento de MicrobiologĂa E InmunologĂa; Argentina. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas; ArgentinaFil: Barros, GermĂĄn Gustavo. Universidad Nacional de RĂo Cuarto. Facultad de Ciencias Exactas, FisicoquĂmicas y Naturales. Departamento de MicrobiologĂa E InmunologĂa; Argentina. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas; ArgentinaFil: Naik, Manjunath K.. College of Agriculture. Department of Plant Pathology; IndiaFil: Wright, Graeme C.. Department of Primary Industries; AustraliaFil: Hell, Kerstin. International Institute of Tropical Agriculture; BenĂnFil: Carbone, Ignazio. University Of North Carolina; Estados Unido
Sexuality Generates Diversity in the Aflatoxin Gene Cluster: Evidence on a Global Scale
Aflatoxins are produced by Aspergillus flavus and A. parasiticus in oil-rich seed and grain crops and are a serious problem in agriculture, with aflatoxin Bâ being the most carcinogenic natural compound known. Sexual reproduction in these species occurs between individuals belonging to different vegetative compatibility groups (VCGs). We examined natural genetic variation in 758 isolates of A. flavus, A. parasiticus and A. minisclerotigenes sampled from single peanut fields in the United States (Georgia), Africa (Benin), Argentina (CĂłrdoba), Australia (Queensland) and India (Karnataka). Analysis of DNA sequence variation across multiple intergenic regions in the aflatoxin gene clusters of A. flavus, A. parasiticus and A. minisclerotigenes revealed significant linkage disequilibrium (LD) organized into distinct blocks that are conserved across different localities, suggesting that genetic recombination is nonrandom and a global occurrence. To assess the contributions of asexual and sexual reproduction to fixation and maintenance of toxin chemotype diversity in populations from each locality/species, we tested the null hypothesis of an equal number of MAT1-1 and MAT1-2 mating-type individuals, which is indicative of a sexually recombining population. All samples were clone-corrected using multi-locus sequence typing which associates closely with VCG. For both A. flavus and A. parasiticus, when the proportions of MAT1-1 and MAT1-2 were significantly different, there was more extensive LD in the aflatoxin cluster and populations were fixed for specific toxin chemotype classes, either the non-aflatoxigenic class in A. flavus or the Bâ-dominant and Gâ-dominant classes in A. parasiticus. A mating type ratio close to 1â¶1 in A. flavus, A. parasiticus and A. minisclerotigenes was associated with higher recombination rates in the aflatoxin cluster and less pronounced chemotype differences in populations. This work shows that the reproductive nature of the population (more sexual versus more asexual) is predictive of aflatoxin chemotype diversity in these agriculturally important fungi
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