43 resultados para Ecological half-life


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OBJECTIVES: The differences between child self-reports and parent proxy reports of quality of life in a large population of children with cerebral palsy were studied. We examined whether child characteristics, severity of impairment, socioeconomic factors, and parental stress were associated with parent proxy reports being respectively higher or lower than child self-reports of quality of life. METHODS. This study was conducted in 2004–2005 and assessed child quality of life (using the Kidscreen questionnaire, 10 domains, each scored 0–100) through self-reports and parent proxy reports of 500 children aged 8 to 12 years who had cerebral palsy and were living in 7 countries in Europe. RESULTS: The mean child-reported scores of quality of life were significantly higher than the parent proxy reports in 8 domains, significantly lower for the finances domain, and similar for the emotions domain. The average frequency of disagreement (child-parent difference greater than half an SD of child scores) over all domains was 64%, with parents rating their child’s quality of life lower than the children themselves in 29% to 57% of child-parent pairs. We found that high levels of stress in parenting negatively influenced parents’ perception of their child’s quality of life, whereas the main factor explaining parents’ ratings of children’s quality of life higher than the children themselves is self-reported severe child pain. CONCLUSIONS: This study shows that the factors associated with disagreement are different according to the direction of disagreement. In particular, parental wellbeing and child pain should be taken into account in the interpretation of parent proxy reports, especially when no child self-report of quality of life is available. In the latter cases, it may be advisable to obtain additional proxy reports (from caregivers, teachers, or clinicians) to obtain complementary information on the child’s quality of life.

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Recent climatic change has been recorded across the globe. Although environmental change is a characteristic feature of life on Earth and has played a major role in the evolution and global distribution of biodiversity, predicted future rates of climatic change, especially in temperature, are such that they will exceed any that has occurred over recent geological time. Climate change is considered as a key threat to biodiversity and to the structure and function of ecosystems that may already be subject to significant anthropogenic stress. The current understanding of climate change and its likely consequences for the fishes of Britain and Ireland and the surrounding seas are reviewed through a series of case studies detailing the likely response of several marine, diadromous and freshwater fishes to climate change. Changes in climate, and in particular, temperature have and will continue to affect fish at all levels of biological organization: cellular, individual, population, species, community and ecosystem, influencing physiological and ecological processes in a number of direct, indirect and complex ways. The response of fishes and of other aquatic taxa will vary according to their tolerances and life stage and are complex and difficult to predict. Fishes may respond directly to climate-change-related shifts in environmental processes or indirectly to other influences, such as community-level interactions with other taxa. However, the ability to adapt to the predicted changes in climate will vary between species and between habitats and there will be winners and losers. In marine habitats, recent changes in fish community structure will continue as fishes shift their distributions relative to their temperature preferences. This may lead to the loss of some economically important cold-adapted species such as Gadus morhua and Clupea harengus from some areas around Britain and Ireland, and the establishment of some new, warm-adapted species. Increased temperatures are likely to favour cool-adapted (e.g. Perca fluviatilis) and warm-adapted freshwater fishes (e.g. roach Rutilus rutilus and other cyprinids) whose distribution and reproductive success may currently be constrained by temperature rather than by cold-adapted species (e.g. salmonids). Species that occur in Britain and Ireland that are at the edge of their distribution will be most affected, both negatively and positively. Populations of conservation importance (e.g. Salvelinus alpinus and Coregonus spp.) may decline irreversibly. However, changes in food-web dynamics and physiological adaptation, for example because of climate change, may obscure or alter predicted responses. The residual inertia in climate systems is such that even a complete cessation in emissions would still leave fishes exposed to continued climate change for at least half a century. Hence, regardless of the success or failure of programmes aimed at curbing climate change, major changes in fish communities can be expected over the next 50 years with a concomitant need to adapt management strategies accordingly.

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Background: After a volcano erupts, a lake may form in the cooled crater and become an isolated aquatic ecosystem. This makes fishes in crater lakes informative for understanding sympatric evolution and ecological diversification in barren environments. From a geological and limnological perspective, such research offers insight about the process of crater lake ecosystem establishment and speciation. In the present study we use genetic and coalescence approaches to infer the colonization history of Midas cichlid fishes (Amphilophus cf. citrinellus) that inhabit a very young crater lake in Nicaragua-the ca. 1800 year-old Lake Apoyeque. This lake holds two sympatric, endemic morphs of Midas cichlid: one with large, hypertrophied lips (~20% of the total population) and another with thin lips. Here we test the associated ecological, morphological and genetic diversification of these two morphs and their potential to represent incipient speciation.
Results: Gene coalescence analyses [11 microsatellite loci and mitochondrial DNA (mtDNA) sequences] suggest that crater lake Apoyeque was colonized in a single event from the large neighbouring great lake Managua only about 100 years ago. This founding in historic times is also reflected in the extremely low nuclear and mitochondrial genetic diversity in Apoyeque. We found that sympatric adult thin- and thick-lipped fishes occupy distinct ecological trophic niches. Diet, body shape, head width, pharyngeal jaw size and shape and stable isotope values all differ significantly between the two lip-morphs. The eco-morphological features pharyngeal jaw shape, body shape, stomach contents and stable isotopes (d15N) all show a bimodal distribution of traits, which is compatible with the expectations of an initial stage of ecological speciation under disruptive selection. Genetic differentiation between the thin- and thick-lipped population is weak at mtDNA sequence (FST = 0.018) and absent at nuclear microsatellite loci (FST < 0.001).
Conclusions: This study provides empirical evidence of eco-morphological differentiation occurring very quickly after the colonization of a new and vacant habitat. Exceptionally low levels of neutral genetic diversity and inference from coalescence indicates that the Midas cichlid population in Apoyeque is much younger (ca. 100 years or generations old) than the crater itself (ca. 1 800 years old). This suggests either that the crater remained empty for many hundreds of years after its formation or that remnant volcanic activity prevented the establishment of a stable fish population during the early life of the crater lake. Based on our findings of eco-morphological variation in the Apoyeque Midas cichlids, and known patterns of adaptation in Midas cichlids in general, we suggest that this population may be in a very early stage of speciation (incipient species), promoted by disruptive selection and ecological diversification.

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Goldstone's idea of slow dynamics resulting from spontaneously broken symmetries is applied to Hubbell's neutral hypothesis of community dynamics, to efficiently simplify stage-structured multi-species models-introducing the quasi-neutral approximation (QNA). Rather than assuming population-dynamical neutrality in the QNA, deviations from ideal neutrality, thought to be small, drive dynamics. The QNA is systematically derived to first and second order in a two-scale singular perturbation expansion. The total reproductive value of species, as computed from the effective life-history parameters resulting from the non-linear interactions with the surrounding community, emerges as the new dynamic variables in this aggregated description. Using a simple stage-structured community-assembly model, the QNA is demonstrated to accurately reproduce population dynamics in large, complex communities. Further, the utility of the QNA in building intuition for management problems is illustrated by estimating the responses of a fish stock to harvesting and variations in fecundity.

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Cerebral palsy is the most common cause of physical disability in childhood and half of these children will have an intellectual impairment. This article reports on the quality of life of children with cerebral palsy and explores the impact of intellectual impairment. Learning disability nurses have a critical role to play in improving the quality of life for this patient group, particularly in relation to their physical health and creating opportunities to promote social skill development and social inclusion.

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Moving beyond simply documenting that political violence negatively impacts children, we tested a social ecological hypothesis for relations between political violence and child outcomes. Participants were 700 mother child (M = 12.1 years, SD = 1.8) dyads from 18 working-class, socially deprived areas in Belfast, Northern Ireland, including single- and two-parent families. Sectarian community violence was associated with elevated family conflict and children's reduced security about multiple aspects of their social environment (i.e., family, parent child relations, and community), with links to child adjustment problems and reductions in prosocial behavior. By comparison, and consistent with expectations, links with negative family processes, child regulatory problems, and child outcomes were less consistent for nonsectarian community violence. Support was found for a social ecological model for relations between political violence and child outcomes among both single- and two-parent families, with evidence that emotional security and adjustment problems were more negatively affected in single-parent families. The implications for understanding social ecologies of political violence and children's functioning are discussed.

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Autism is a neuro-developmental disorder defined by atypical social behaviour, of which atypical social attention behaviours are among the earliest clinical markers (Volkmar et al., 1997). Eye tracking studies using still images and movie clips have provided a method for the precise quantification of atypical social attention in ASD. This is generally characterised by diminished viewing of the most socially pertinent regions (eyes), and increased viewing of less socially informative regions (body, background, objects) (Klin et al., 2002; Riby & Hancock, 2008, 2009). Ecological validity within eye tracking studies has become an increasingly important issue. As of yet, however, little is known about the precise nature of the atypicalities of social attention in ASD in real-life. Objectives: To capture and quantify gaze patterns for children with an ASD within a real life setting, compared to two Typically Developing (TD) comparison groups. Methods: Nine children with an ASD were compared to two age matched TD groups – a verbal (N=9) and a non-verbal (N=9) comparison group. A real-life scenario was created involving an experimenter posing as a magician, and consisted of 3 segments: a conversation segment; a magic trick segment; and a puppet segment. The first segment explored children’s attentional preferences during a real-life conversation; the magic trick segment explored children’s use of the eyes as a communicative cue, and the puppet segment explored attention capture. Finally, part of the puppet section explored children’s use of facial information in response to an unexpected event. Results: The most striking difference between the groups was the diminished viewing of the eyes by the ASD group in comparison to both control groups. This was found particularly during the conversation segment, but also during the magic trick segment, and during the puppet segment. When in conversation, participants with ASD were found to spend a greater proportion time looking off-screen, in comparison to TD participants. There was also a tendency for the ASD group to spend a greater proportion of time looking to the mouth of the experimenter. During the magic trick segment, despite the fact that the eyes were not predictive of a correct location, both TD comparison groups continued to use the eyes as a communicative cue, whereas the ASD group did not. In the puppet segment, all three groups spent a similar amount of time looking between the puppet and regions of the experimenter’s face. However, in response to an unexpected event, the ASD group were significantly slower to fixate back on the experimenter’s face. Conclusions: The results demonstrate the reduced salience of socially pertinent information for children with ASD in real life, and they provide support for the findings from previous eye tracking studies involving scene viewing. However, the results also highlight a pattern looking off-screen for both the TD and ASD groups. This eye movement behaviour is likely to be associated specifically with real-life interaction, as it has functional relevance (Doherty-Sneddon et al., 2002). However, the fact that it is significantly increased in the ASD group has implications for their understanding of real life social interactions.

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The study of parallel evolution facilitates the discovery of common rules of diversification. Here, we examine the repeated evolution of thick lips in Midas cichlid fishes (the Amphilophus citrinellus species complex) - from two Great Lakes and two crater lakes in Nicaragua - to assess whether similar changes in ecology, phenotypic trophic traits and gene expression accompany parallel trait evolution. Using next-generation sequencing technology, we characterize transcriptome-wide differential gene expression in the lips of wild-caught sympatric thick- and thin-lipped cichlids from all four instances of repeated thick-lip evolution. Six genes (apolipoprotein D, myelin-associated glycoprotein precursor, four-and-a-half LIM domain protein 2, calpain-9, GTPase IMAP family member 8-like and one hypothetical protein) are significantly underexpressed in the thick-lipped morph across all four lakes. However, other aspects of lips' gene expression in sympatric morphs differ in a lake-specific pattern, including the magnitude of differentially expressed genes (97-510). Generally, fewer genes are differentially expressed among morphs in the younger crater lakes than in those from the older Great Lakes. Body shape, lower pharyngeal jaw size and shape, and stable isotopes (dC and dN) differ between all sympatric morphs, with the greatest differentiation in the Great Lake Nicaragua. Some ecological traits evolve in parallel (those related to foraging ecology; e.g. lip size, body and head shape) but others, somewhat surprisingly, do not (those related to diet and food processing; e.g. jaw size and shape, stable isotopes). Taken together, this case of parallelism among thick- and thin-lipped cichlids shows a mosaic pattern of parallel and nonparallel evolution. © 2012 Blackwell Publishing Ltd.

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Objectives: Family caregivers play a vital role in maintaining the lives of individuals with advanced illness living in the community. However, the responsibility of caregiving for an end-of-life family member can have profound consequences on the psychological, physical and financial well-being of the caregiver. While the literature has identified caregiver stress or strain as a complex process with multiple contributing factors, few comprehensive studies exist. This study examined a wide range of theory-driven variables contributing to family caregiver stress. Method: Data variables from interviews with primary family caregivers were mapped onto the factors within the Stress Process Model theoretical framework. A hierarchical multiple linear regression analysis was used to determine the strongest predictors of caregiver strain as measured by a validated composite index, the Caregiver Strain Index. Results: The study included 132 family caregivers across south-central/western Ontario, Canada. About half of these caregivers experienced high strain, the extent of which was predicted by lower perceived program accessibility, lower functional social support, greater weekly amount of time caregivers committed to the care recipient, younger caregiver age and poorer caregiver self-perceived health. Conclusion: This study examined the influence of a multitude of factors in the Stress Process Model on family caregiver strain, finding stress to be a multidimensional construct. Perceived program accessibility was the strongest predictor of caregiver strain, more so than intensity of care, highlighting the importance of the availability of community resources to support the family caregiving role.

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Approximately 90% of the UK population spend some time in hospital in their final year of life, and more than half of the population die in hospital. This review aims to explore the experiences of general nurses when providing end-of-life care to patients in the acute hospital setting. Nine studies were identified through a literature search, and each was then analysed and evaluated until themes emerged. Six themes were drawn from the literature: lack of education and knowledge, lack of time with patients, barriers arising in the culture of the health-care setting, communication barriers, symptom management, and nurses' personal issues. The themes cause concern about the quality of end-of-life care being provided in the acute care setting. The literature appears to be consistent in the view that terminally ill patients are best cared for in specialised care settings, such as palliative care units and hospices. However, increasing demands on health services will result in greater numbers of dying patients being admitted to the acute hospital setting. It is therefore paramount that general nurses' educational needs are met to ensure they develop clinical competence to provide high-quality holistic end-of-life care.

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Fundamental ecological research is both intrinsically interesting and provides the basic knowledge required to answer applied questions of importance to the management of the natural world. The 100th anniversary of the British Ecological Society in 2013 is an opportune moment to reflect on the current status of ecology as a science and look forward to high-light priorities for future work. To do this, we identified 100 important questions of fundamental importance in pure ecology. We elicited questions from ecologists working across a wide range of systems and disciplines. The 754 questions submitted (listed in the online appendix) from 388 participants were narrowed down to the final 100 through a process of discussion, rewording and repeated rounds of voting. This was done during a two-day workshop and thereafter. The questions reflect many of the important current conceptual and technical pre-occupations of ecology. For example, many questions concerned the dynamics of environmental change and complex ecosystem interactions, as well as the interaction between ecology and evolution. The questions reveal a dynamic science with novel subfields emerging. For example, a group of questions was dedicated to disease and micro-organisms and another on human impacts and global change reflecting the emergence of new subdisciplines that would not have been foreseen a few decades ago. The list also contained a number of questions that have perplexed ecologists for decades and are still seen as crucial to answer, such as the link between population dynamics and life-history evolution. Synthesis. These 100 questions identified reflect the state of ecology today. Using them as an agenda for further research would lead to a substantial enhancement in understanding of the discipline, with practical relevance for the conservation of biodiversity and ecosystem function. © 2013 The Authors. Journal of Ecology © 2013 British Ecological Society.

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Fibre-Reinforced Plastics (FRPs) have been used in civil aerospace vehicles for decades. The current state-of-the-art in airframe design and manufacture results in approximately half the airframe mass attributable to FRP materials. The continual increase in the use of FRP materials over metallic alloys is attributable to the material's superior specific strength and stiffness, fatigue performance and corrosion resistance. However, the full potential of these materials has yet to be exploited as analysis methods to predict physical failure with equal accuracy and robustness are not yet available. The result is a conservative approach to design, but one that can bring benefit via increased inspection intervals and reduced cost over the vehicle life. The challenge is that the methods used in practice are based on empirical tests and real relationships and drivers are difficult to see in this complex process and so the trade-off decision is challenging and uncertain. The aim of this feasibility study was to scope a viable process which could help develop some rules and relationships based on the fundamental mechanics of composite material and the economics of production and operation, which would enhance understanding of the role and impact of design allowables across the life of a composite structure.

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The use of cathodic protection in reinforced concrete is becoming increasingly common with such systems being installed on a number of structures throughout the United Kingdom and Ireland. However the prescribed design lives (or service life) of each cathodic protection system vary widely. The aim of this project was to assess the effectiveness of a sacrificial anode cathodic protection system and to predict its design life through a series of laboratory based experiments. The experimental plan involved casting a number of slabs which represented a common road bridge structure. The corrosion of the steel within the experimental slabs was then accelerated prior to installation of a cathodic protection system. During the experiment corrosion potential of the steel reinforcement was monitored using half-cell measurement. Additionally the current flow between the cathodic protection system and the steel reinforcement was recorded to assess the degree of protection. A combination of theoretical calculations and experimental results were then collated to determine the design life of this cathodic protection system. It can be concluded that this sacrificial anode based cathodic protection system was effective in halting the corrosion of steel reinforcement in the concrete slabs studied. Both the corrosion current and half-cell potentials indicated a change in passivity for the steel reinforcement once sacrificial anodes were introduced. The corrosion current was observed to be sensitive to the changes to the exposure environment. Based on the experimental variables studied the design life of this sacrificial anode can be taken as 26 to 30 years.