1,552 research outputs found

    Fitness correlates of blubber oxidative stress and cellular defences in grey seals (<i>Halichoerus grypus</i>):support for the life-history-oxidative stress theory from an animal model of simultaneous lactation and fasting

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    Life-history-oxidative stress theory predicts that elevated energy costs during reproduction reduce allocation to defences and increase cellular stress, with fitness consequences, particularly when resources are limited. As capital breeders, grey seals are a natural system in which to test this theory. We investigated oxidative damage (malondialdehyde (MDA) concentration) and cellular defences (relative mRNA abundance of heat shock proteins (Hsps) and redox enzymes (REs)) in blubber of wild female grey seals during the lactation fast (n = 17) and summer foraging (n = 13). Transcript abundance of Hsc70 increased, and Nox4, a pro-oxidant enzyme, decreased throughout lactation. Foraging females had higher mRNA abundance of some Hsps and lower RE transcript abundance and MDA concentrations, suggesting they experienced lower oxidative stress than lactating mothers, which diverted resources into pup rearing at the expense of blubber tissue damage. Lactation duration and maternal mass loss rate were both positively related to pup weaning mass. Pups whose mothers had higher blubber glutathione-S-transferase (GST) expression at early lactation gained mass more slowly. Higher glutathione peroxidase (GPx) and lower catalase (CAT) were associated with longer lactation but reduced maternal transfer efficiency and lower pup weaning mass. Cellular stress, and the ability to mount effective cellular defences, could proscribe lactation strategy in grey seal mothers and thus affect pup survival probability. These data support the life-history-oxidative stress hypothesis in a capital breeding mammal and suggest lactation is a period of heightened vulnerability to environmental factors that exacerbate cellular stress. Fitness consequences of stress may thus be accentuated during periods of rapid environmental change

    EUV spectra of highly-charged ions W54+^{54+}-W63+^{63+} relevant to ITER diagnostics

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    We report the first measurements and detailed analysis of extreme ultraviolet (EUV) spectra (4 nm to 20 nm) of highly-charged tungsten ions W54+^{54+} to W63+^{63+} obtained with an electron beam ion trap (EBIT). Collisional-radiative modelling is used to identify strong electric-dipole and magnetic-dipole transitions in all ionization stages. These lines can be used for impurity transport studies and temperature diagnostics in fusion reactors, such as ITER. Identifications of prominent lines from several W ions were confirmed by measurement of isoelectronic EUV spectra of Hf, Ta, and Au. We also discuss the importance of charge exchange recombination for correct description of ionization balance in the EBIT plasma.Comment: 11 pages, 4 figure

    Local Optical Probe of Motion and Stress in a multilayer graphene NEMS

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    Nanoelectromechanical systems (NEMSs) are emerging nanoscale elements at the crossroads between mechanics, optics and electronics, with significant potential for actuation and sensing applications. The reduction of dimensions compared to their micronic counterparts brings new effects including sensitivity to very low mass, resonant frequencies in the radiofrequency range, mechanical non-linearities and observation of quantum mechanical effects. An important issue of NEMS is the understanding of fundamental physical properties conditioning dissipation mechanisms, known to limit mechanical quality factors and to induce aging due to material degradation. There is a need for detection methods tailored for these systems which allow probing motion and stress at the nanometer scale. Here, we show a non-invasive local optical probe for the quantitative measurement of motion and stress within a multilayer graphene NEMS provided by a combination of Fizeau interferences, Raman spectroscopy and electrostatically actuated mirror. Interferometry provides a calibrated measurement of the motion, resulting from an actuation ranging from a quasi-static load up to the mechanical resonance while Raman spectroscopy allows a purely spectral detection of mechanical resonance at the nanoscale. Such spectroscopic detection reveals the coupling between a strained nano-resonator and the energy of an inelastically scattered photon, and thus offers a new approach for optomechanics

    Repetitive arm functional tasks after stroke (RAFTAS): a pilot randomised controlled trial

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    Background Repetitive functional task practise (RFTP) is a promising treatment to improve upper limb recovery following stroke. We report the findings of a study to determine the feasibility of a multi-centre randomised controlled trial to evaluate this intervention. Methods A pilot randomised controlled trial was conducted. Patients with new reduced upper limb function were recruited within 14 days of acute stroke from three stroke units in North East England. Participants were randomised to receive a four week upper limb RFTP therapy programme consisting of goal setting, independent activity practise, and twice weekly therapy reviews in addition to usual post stroke rehabilitation, or usual post stroke rehabilitation. The recruitment rate; adherence to the RFTP therapy programme; usual post stroke rehabilitation received; attrition rate; data quality; success of outcome assessor blinding; adverse events; and the views of study participants and therapists about the intervention were recorded. Results Fifty five eligible patients were identified, 4-6% of patients screened at each site. Twenty four patients participated in the pilot study. Two of the three study sites met the recruitment target of 1-2 participants per month. The median number of face to face therapy sessions received was 6 [IQR 3-8]. The median number of daily repetitions of activities recorded was 80 [IQR 39-80]. Data about usual post stroke rehabilitation were available for 18/24 (75%). Outcome data were available for 22/24 (92%) at one month and 20/24 (83%) at three months. Outcome assessors were unblinded to participant group allocation for 11/22 (50%) at one month and 6/20 (30%) at three months. Four adverse events were considered serious as they resulted in hospitalisation. None were related to study treatment. Feedback from patients and local NHS therapists about the RFTP programme was mainly positive. Conclusions A multi-centre randomised controlled trial to evaluate an upper limb RFTP therapy programme provided early after stroke is feasible and acceptable to patients and therapists, but there are issues which needed to be addressed when designing a Phase III study. A Phase III study will need to monitor and report not only recruitment and attrition but also adherence to the intervention, usual post stroke rehabilitation received, and outcome assessor blinding

    Conserving the birds of Uganda's Banana-Coffee Arc: Land Sparing and Land Sharing Compared

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    Reconciling the aims of feeding an ever more demanding human population and conserving biodiversity is a difficult challenge. Here, we explore potential solutions by assessing whether land sparing (farming for high yield, potentially enabling the protection of non-farmland habitat), land sharing (lower yielding farming with more biodiversity within farmland) or a mixed strategy would result in better bird conservation outcomes for a specified level of agricultural production. We surveyed forest and farmland study areas in southern Uganda, measuring the population density of 256 bird species and agricultural yield: food energy and gross income. Parametric non-linear functions relating density to yield were fitted. Species were identified as "winners" (total population size always at least as great with agriculture present as without it) or "losers" (total population sometimes or always reduced with agriculture present) for a range of targets for total agricultural production. For each target we determined whether each species would be predicted to have a higher total population with land sparing, land sharing or with any intermediate level of sparing at an intermediate yield. We found that most species were expected to have their highest total populations with land sparing, particularly loser species and species with small global range sizes. Hence, more species would benefit from high-yield farming if used as part of a strategy to reduce forest loss than from low-yield farming and land sharing, as has been found in Ghana and India in a previous study. We caution against advocacy for high-yield farming alone as a means to deliver land sparing if it is done without strong protection for natural habitats, other ecosystem services and social welfare. Instead, we suggest that conservationists explore how conservation and agricultural policies can be better integrated to deliver land sparing by, for example, combining land-use planning and agronomic support for small farmers

    Local climate determines vulnerability to camouflage mismatch in snowshoe hares

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    AimPhenological mismatches, when life‐events become mistimed with optimal environmental conditions, have become increasingly common under climate change. Population‐level susceptibility to mismatches depends on how phenology and phenotypic plasticity vary across a species’ distributional range. Here, we quantify the environmental drivers of colour moult phenology, phenotypic plasticity, and the extent of phenological mismatch in seasonal camouflage to assess vulnerability to mismatch in a common North American mammal.LocationNorth America.Time period2010–2017.Major taxa studiedSnowshoe hare (Lepus americanus).MethodsWe used > 5,500 by‐catch photographs of snowshoe hares from 448 remote camera trap sites at three independent study areas. To quantify moult phenology and phenotypic plasticity, we used multinomial logistic regression models that incorporated geospatial and high‐resolution climate data. We estimated occurrence of camouflage mismatch between hares’ coat colour and the presence and absence of snow over 7 years of monitoring.ResultsSpatial and temporal variation in moult phenology depended on local climate conditions more so than on latitude. First, hares in colder, snowier areas moulted earlier in the fall and later in the spring. Next, hares exhibited phenotypic plasticity in moult phenology in response to annual variation in temperature and snow duration, especially in the spring. Finally, the occurrence of camouflage mismatch varied in space and time; white hares on dark, snowless background occurred primarily during low‐snow years in regions characterized by shallow, short‐lasting snowpack.Main conclusionsLong‐term climate and annual variation in snow and temperature determine coat colour moult phenology in snowshoe hares. In most areas, climate change leads to shorter snow seasons, but the occurrence of camouflage mismatch varies across the species’ range. Our results underscore the population‐specific susceptibility to climate change‐induced stressors and the necessity to understand this variation to prioritize the populations most vulnerable under global environmental change.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/154444/1/geb13049.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/154444/2/geb13049_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/154444/3/geb13049-sup-0001-Supinfo.pd

    'It's small steps, but that leads to bigger changes': evaluation of a nurture group intervention

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    This article presents the results of a small-scale research project that aimed to evaluate the effectiveness of a part-time nurture group recently established in one primary school. Qualitative interviews were used to gather staff, pupil and parental perceptions about the nurture group. These focused on what difference the nurture group was making to the pupils concerned but also on views about what factors contributed to noted changes. All stakeholder groups identified areas of development for nurture group pupils. These included improved social skills, growth in personal confidence, greater engagement with academic tasks, and fewer incidences of undesirable behaviour. The evidence gathered so far suggests that the nurture group offered an effective way of supporting the social, emotional and behavioural skills of a group of 'at-risk' pupils. A range of factors thought to be important in achieving these outcomes are highlighted. These align broadly with the theoretical underpinnings of nurture groups
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