55 resultados para Antarctic Thresholds - Ecosystem Resilience and Adaptation


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AIM: The aim of this study was to explore the concepts of 'resilience' and 'hardiness' in nursing and midwifery students in educational settings and to identify educational interventions to promote resilience.

BACKGROUND: Resilience in healthcare professionals has gained increasing attention globally, yet to date resilience and resilience education in nursing and midwifery students remain largely under-researched.

DESIGN: An integrative literature review was planned, however, only quantitative evidence was identified therefore, a review of quantitative studies was undertaken using a systematic approach.

DATA SOURCES: A comprehensive search was undertaken using Medline, CINAHL, Embase, PsycINFO and Maternity and Infant Care databases January 1980-February 2015.

REVIEW METHODS: Data were extracted using a specifically designed form and quality assessed using an appropriate checklist. A narrative summary of findings and statistical outcomes was undertaken.

RESULTS: Eight quantitative studies were included. Research relating to resilience and resilience education in nursing and midwifery students is sparse. There is a weak evidence that resilience and hardiness is associated with slightly improved academic performance and decreased burnout. However, studies were heterogeneous in design and limited by poor methodological quality. No study specifically considered student midwives.

CONCLUSION: A greater understanding of the theoretical underpinnings of resilience in nursing and midwifery students is essential for the development of educational resources. It is imperative that future research considers both nursing and midwifery training cohorts and should be of strong methodological quality.

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The colonial census was a bureaucratic device which provided an essential abstraction from social reality, a ‘statistical fix’ designed to map individual social groups in space. This paper considers the contradictions associated with colonial knowledge systems as reflected in the census grafted onto Burmese society in the nineteenth and early twentieth centuries. It attempts to chart the general adoption and adaptation, in the Burmese context, of a classificatory scheme which categorised labour as either productive or unproductive. Colonialism introduced new attitudes towards work and labour which reinforced patriarchal values which contrasted with more egalitarian Burmese socio-economic systems. The paper suggests that a simple classification of women workers as either productive or unproductive in the Burmese census between 1872 and 1931 resulted in the devaluation of their status as workers. This devaluation was a function of both real economic transformation taking place in the empire and changes in census classification, reflecting a gendering of occupations that undermined the cultural norms of Burmese society. The material result was that women became statistically less visible as economically productive workers. Such ascriptions of value to women workers were largely informed by moral considerations originating in England.

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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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A question central to modelling and, ultimately, managing food webs concerns the dimensionality of trophic niche space, that is, the number of independent traits relevant for determining consumer-resource links. Food-web topologies can often be interpreted by assuming resource traits to be specified by points along a line and each consumer's diet to be given by resources contained in an interval on this line. This phenomenon, called intervality, has been known for 30 years and is widely acknowledged to indicate that trophic niche space is close to one-dimensional. We show that the degrees of intervality observed in nature can be reproduced in arbitrary-dimensional trophic niche spaces, provided that the processes of evolutionary diversification and adaptation are taken into account. Contrary to expectations, intervality is least pronounced at intermediate dimensions and steadily improves towards lower- and higher-dimensional trophic niche spaces.

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Objectives: Laryngo-hypopharyngeal sensitivity (LPS) as measured by thresholds to mechanostimulation and chemostimulation is important in the prevention of pulmonary aspiration. The presence of gastroesophageal reflux disease (GERD) increases thresholds to mechanostimulation. However, the effect of GERD on thresholds to chemostimulation remains unknown. The aim of this study was to compare laryngo-hypopharyngeal thresholds to chemostimulation in subjects with GERD with those of healthy subjects and to determine the relationship between thresholds to mechanostimulation and chemostimulation.

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The pattern of predator-prey interactions is thought to be a key determinant of ecosystem processes and stability. Complex ecological networks are characterized by distributions of interaction strengths that are highly skewed, with many weak and few strong interactors present. Theory suggests that this pattern promotes stability as weak interactors dampen the destabilizing potential of strong interactors. Here, we present an experimental test of this hypothesis and provide empirical evidence that the loss of weak interactors can destabilize communities in nature. We ranked 10 marine consumer species by the strength of their trophic interactions. We removed the strongest and weakest of these interactors from experimental food webs containing >100 species. Extinction of strong interactors produced a dramatic trophic cascade and reduced the temporal stability of key ecosystem process rates, community diversity and resistance to changes in community composition. Loss of weak interactors also proved damaging for our experimental ecosystems, leading to reductions in the temporal and spatial stability of ecosystem process rates, community diversity, and resistance. These results highlight the importance of conserving species to maintain the stabilizing pattern of trophic interactions in nature, even if they are perceived to have weak effects in the system.

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NPM has been generally regarded as an administrative reform for which resilience and consequences have been mainly investigated at a country level. Although accounting played a central role in NPM reforms over the last decades, how accounting change actually took place, and through what organizational dynamics, has been under-investigated. This paper adopts a new perspective, archetype theory, and looks into how intra-organizational dynamics (values, interests, power, capabilities) combine with reform processes to influence the outcome of accounting change. Evidence from Italian (disruptive process) and Canadian (sedimented process) municipalities shows that radical change is associated with specific configurations of intra-organizational dynamics.

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1. Global declines in biodiversity have stimulated much research into the consequences of species loss for ecosystems and the goods and services they provide. Species at higher trophic levels are at greater risk of human-induced extinction yet remarkably little is known about the effects of consumer species loss across multiple trophic levels in natural complex ecosystems. Previous studies have been criticized for lacking experimental realism and appropriate temporal scale, running for short periods that are not sufficient to detect many of the mechanisms operating in the field.
2. We manipulated the presence of two predator species and two groups of their prey (primary consumers) and measured their independent and interactive effects on primary producers in a natural marine benthic system. The presence of predators and their prey was manipulated in the field for 14 months to distinguish clearly the direct and indirect effects of predators on primary producers and to identify mechanisms driving responses.
3. We found that the loss of either predator species had indirect negative effects on species diversity and total cover of primary producers. These cascading effects of predator species loss were mediated by the presence of intermediate consumers. Moreover, the presence of different intermediate consumers, irrespective of the presence or absence of their predators, determined primary producer assemblage structure. We identified direct negative effects of predators on their prey and several indirect effects of predators on primary producers but not all interactions could have been predicted based on trophic level.
4. Our findings demonstrate the importance of trophic cascade effects coupled with non-trophic interactions when predicting the effects of loss of predator species on primary producers and consequently for ecosystem functioning. There is a pressing need for improved understanding of the effects of loss of consumers, based on realistic scenarios of diversity loss, to test conceptual frameworks linking predator diversity to variation in ecosystem functioning and for the protection of biodiversity, ecosystem functioning and related services.

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Understanding how communities assemble is a key challenge in ecology. Conflicting hypotheses suggest that plant traits within communities should show divergence to reflect strategies to reduce competition or convergence to reflect strong selection for the environmental conditions operating. Further hypotheses suggest that plant traits related to productivity show convergence within communities, but those related to disturbance show divergence. Data on functional diversity (FD ) of 12 traits from 30 communities ranging from arable fields, mown and grazed grasslands to moorland and woodland were employed to test this using randomisations tests and correlation and regression analysis. No traits showed consistent significant convergence or divergence in functional diversity. When correlated to measures of the environment, the most common pattern was for functional diversity to decline (7 out of 12 traits) and the degree of convergence (7 out of 12 traits) to increase as the levels of productivity (measured as primary productivity, soil nitrogen release and vegetation C:N) and disturbance increased. Convergence or a relationship between functional diversity and the environment was not seen for a number of important traits, such as LDMC and SLA, which are considered as key predictors of ecosystem function. The analysis indicates that taking into account functional diversity within a system may be a necessary part of predicting the relationship between plant traits and ecosystem function, and that this may be of particular importance within less productive and less disturbed systems. © 2011 Springer-Verlag.

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Cathepsin L proteases secreted by the helminth pathogen Fasciola hepatica have functions in parasite virulence including tissue invasion and suppression of host immune responses. Using proteomics methods alongside phylogenetic studies we characterized the profile of cathepsin L proteases secreted by adult F. hepatica and hence identified those involved in host-pathogen interaction. Phylogenetic analyses showed that the Fasciola cathepsin L gene family expanded by a series of gene duplications followed by divergence that gave rise to three clades associated with mature adult worms (Clades 1, 2, and 5) and two clades specific to infective juvenile stages (Clades 3 and 4). Consistent with these observations our proteomics studies identified representatives from Clades 1, 2, and 5 but not from Clades 3 and 4 in adult F. hepatica secretory products. Clades 1 and 2 account for 67.39 and 27.63% of total secreted cathepsin Ls, respectively, suggesting that their expansion was positively driven and that these proteases are most critical for parasite survival and adaptation. Sequence comparison studies revealed that the expansion of cathepsin Ls by gene duplication was followed by residue changes in the S2 pocket of the active site. Our biochemical studies showed that these changes result in alterations in substrate binding and suggested that the divergence of the cathepsin L family produced a repertoire of enzymes with overlapping and complementary substrate specificities that could cleave host macromolecules more efficiently. Although the cathepsin Ls are produced as zymogens containing a prosegment and mature domain, all secreted enzymes identified by MS were processed to mature active enzymes. The prosegment region was highly conserved between the clades except at the boundary of prosegment and mature enzyme. Despite the lack of conservation at this section, sites for exogenous cleavage by asparaginyl endopeptidases and a Leu-Ser[downward arrow]His motif for autocatalytic cleavage by cathepsin Ls were preserved.

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Context: The development of a consolidated knowledge base for social work requires rigorous approaches to identifying relevant research. Method: The quality of 10 databases and a web search engine were appraised by systematically searching for research articles on resilience and burnout in child protection social workers. Results: Applied Social Sciences Index and Abstracts, Social Services Abstracts and Social Sciences Citation Index (SSCI) had greatest sensitivity, each retrieving more than double than any other database. PsycINFO and Cumulative Index to Nursing and Allied Health (CINAHL) had highest precision. Google Scholar had modest sensitivity and good precision in relation to the first 100 items. SSCI, Google Scholar, Medline, and CINAHL retrieved the highest number of hits not retrieved by any other database. Conclusion: A range of databases is required for even modestly comprehensive searching. Advanced database searching methods are being developed but the profession requires greater standardization of terminology to assist in information retrieval.