4,387 research outputs found

    The role of biological interactions in modifying the effects of climate change on intertidal assemblages

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    The geographic distribution of most species is expected to alter as a consequence of global climate change. Predictions for the extent of these range shifts are frequently based on anticipated changes in temperature using a 'climate envelope' approach, which oversimplifies predictions because it does not consider interactions with other physical and biological factors. The aim of this thesis was to investigate how biological interactions modulate species responses to climate change. On many rocky shores in the NE Atlantic the interaction between limpets, barnacles and canopy forming macroalgae have an important role in structuring rocky shore communities. In particular, limpets control the abundance of macroalgae on the shore through their grazing activities. Through descriptive studies and manipulative experiments the behaviour of a northern/boreal species of limpet, Patella vulgata and a southern/lusitanian species of limpet, P. depressa were compared in relation to canopy forming algae (Fucus patches). As a result of differences in the spatial distribution, behaviour and grazing activity of these two species, if as predicted, there are changes in their relative abundance it is likely there will be implications for rocky shore community dynamics. The second part of my thesis investigated intra- and interspecific competition between two coexisting barnacle taxa with northern and southern centres of distribution. It is predicted that Increased warming will result in a reduction in the abundance of Semibalanus balanoides either as a direct result of increased temperatures or due to an increase in the number of poor spawning years. My results suggest that as a consequence of the gregarious nature of settling S. balanoides cyprids, recruitment success may be reduced irrespective of the numbers of cyprids in the plankton. This will result in more space becoming available for the competing and later settling Chthamalus spp, resulting in a change in barnacle population structure. The likely impacts of population changes and species range shifts in response to increased warming are discussed, with particular emphasis on how the interaction between limpets, barnacles and Fucus may alter. The implications of altered species interactions are then discussed in terms of the effects on community dynamics and ecosystem functioning. Finally the role of biotic interactions in modulating species responses to climate change are discussed with reference to the use of the 'climate envelope' approach in making predictions of species range shifts

    Do topical repellents divert mosquitoes within a community? Health equity implications of topical repellents as a mosquito bite prevention tool.

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    OBJECTIVES: Repellents do not kill mosquitoes--they simply reduce human-vector contact. Thus it is possible that individuals who do not use repellents but dwell close to repellent users experience more bites than otherwise. The objective of this study was to measure if diversion occurs from households that use repellents to those that do not use repellents. METHODS: The study was performed in three Tanzanian villages using 15%-DEET and placebo lotions. All households were given LLINs. Three coverage scenarios were investigated: complete coverage (all households were given 15%-DEET), incomplete coverage (80% of households were given 15%-DEET and 20% placebo) and no coverage (all households were given placebo). A crossover study design was used and coverage scenarios were rotated weekly over a period of ten weeks. The placebo lotion was randomly allocated to households in the incomplete coverage scenario. The level of compliance was reported to be close to 100%. Mosquito densities were measured through aspiration of resting mosquitoes. Data were analysed using negative binomial regression models. FINDINGS: Repellent-users had consistently fewer mosquitoes in their dwellings. In villages where everybody had been given 15%-DEET, resting mosquito densities were fewer than half that of households in the no coverage scenario (Incidence Rate Ratio [IRR]=0.39 (95% confidence interval [CI]: 0.25-0.60); p<0.001). Placebo-users living in a village where 80% of the households used 15%-DEET were likely to have over four-times more mosquitoes (IRR=4.17; 95% CI: 3.08-5.65; p<0.001) resting in their dwellings in comparison to households in a village where nobody uses repellent. CONCLUSIONS: There is evidence that high coverage of repellent use could significantly reduce man-vector contact but with incomplete coverage evidence suggests that mosquitoes are diverted from households that use repellent to those that do not. Therefore, if repellents are to be considered for vector control, strategies to maximise coverage are required

    A crossover study to evaluate the diversion of malaria vectors in a community with incomplete coverage of spatial repellents in the Kilombero Valley, Tanzania

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    Malaria elimination is unlikely to occur if vector control efforts focus entirely on transmission occurring indoors without addressing vectors that bite outdoors and outside sleeping hours. Additional control tools such as spatial repellents may provide the personal protection required to fill this gap. However, since repellents do not kill mosquitoes it is unclear if vectors will be diverted from households that use spatial repellents to those that do not.; A crossover study was performed over 24 weeks in Kilombero, Tanzania. The density of resting and blood-engorged mosquitoes and human blood index (HBI) of malaria vector species per household was measured among 90 households using or not using 0.03 % transfluthrin coils burned outdoors under three coverage scenarios: (i) no coverage (blank coils); (ii) complete coverage of repellent coils; and (iii) incomplete coverage of repellent and blank coils. Mosquitoes were collected three days a week for 24 weeks from the inside and outside of all participating households using mosquito aspirators. Paired indoor and outdoor human landing collections were performed in three random households for six consecutive nights to confirm repellent efficacy of the coils and local vector biting times.; The main vectors were Anopheles arabiensis and Anopheles funestus (sensu stricto), which fed outdoors, outside sleeping hours, on humans as well as animals. Anopheles arabiensis landings were reduced by 80 % by the spatial repellent although household densities were not reduced. The HBI for An. arabiensis was significantly higher among households without repellents in the incomplete coverage scenario compared to houses in the no coverage scenario (Odds ratio 1.71; 95 % CI: 1.04-2.83; P = 0.03). This indicated that An. arabiensis mosquitoes seeking a human blood meal were diverted from repellent users to non-users. The repellent coils did not affect An. funestus densities or HBI.; Substantial malaria vector activity is occurring outside sleeping hours in the Kilombero valley. Repellent coils provided some protection against local An. arabiensis but did not protect against local (and potentially pyrethroid-resistant) An. funestus. Pyrethroid-based spatial repellents may offer a degree of personal protection, however the overall public health benefit is doubtful and potentially iniquitous as their use may divert malaria vectors to those who do not use them

    Male-biased predation and its effect on paternity skew and life history in a population of common brushtail possums (Trichosurus vulpecula)

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    Differences in predation risk may exert strong selective pressures on life history strategies of populations. We investigated the potential for predation to shape male mating strategies in an arboreal folivore, the common brushtail possum (Trichosurus vulpecula Kerr). We predicted that possums in a tropical population exposed to high natural levels of predation would grow faster and reproduce earlier compared to those in temperate populations with lower predation. We trapped a population of possums in eucalypt woodland in northern Australia each month to measure life history traits and used microsatellites to genotype all individuals and assign paternity to all offspring. We observed very high levels of male-biased predation, with almost 60% of marked male possums being eaten by pythons, presumably as a result of their greater mobility due to mate-searching. Male reproductive success was also highly skewed, with younger, larger males fathering significantly more offspring. This result contrasts with previous studies of temperate populations experiencing low levels of predation, where older males were larger and the most reproductively successful. Our results suggest that in populations exposed to high levels of predation, male possums invest in increased growth earlier in life, in order to maximise their mating potential. This strategy is feasible because predation limits competition from older males and means that delaying reproduction carries a risk of failing to reproduce at all. Our results show that life histories are variable traits that can match regional predation environments in mammal species with widespread distributions.This work was supported by the Australian Research Council http://www.arc.gov.au/ Grant number DP0449621 to CNJ, DP0449544 to WJF. JLD was supported by an Australian National University Graduate School Scholarship

    Troubling stoicism:Sociocultural influences and applications to health and illness behaviour

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    In light of the ambiguity of meanings attributed to the concept of stoicism we critically explore its use as a label to explain and describe health and illness behaviour, juxtaposing the often negative portrayals of contemporary stoicism against its classical and philosophical origins. By reflecting critically on the term ‘stoicism’, its application and dimensionality, we show how the term has evolved from classical to contemporary times in relation to changing context, and explore different understandings of the term across medical and health literature. We attend to sociocultural factors that are seen to influence the conceptualization of stoicism such as generational influences, gender and geographies. We make the assertion that by applying the label of ‘stoicism’ as it is known today, there is a danger of too readily accepting a term that masks particular health behaviours while missing an array of sociological factors that are important to how people deal with adversity arising from chronic health problems. We therefore encourage further questioning of this term. </jats:p

    Outcomes and patients’ perspectives of transition from paediatric to adult care in inflammatory bowel disease

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    This article is an open-access article which was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: http://creativecommons.org/ licenses/by-nc/4.0/AIM: To describe the disease and psychosocial outcomes of an inflammatory bowel disease (IBD) transition cohort and their perspectives. METHODS: Patients with IBD, aged > 18 years, who had moved from paediatric to adult care within 10 years were identified through IBD databases at three tertiary hospitals. Participants were surveyed regarding demographic and disease specific data and their perspectives on the transition process. Survey response data were compared to contemporaneously recorded information in paediatric service case notes. Data were compared to a similar age cohort who had never received paediatric IBD care and therefore who had not undergone a transition process. RESULTS: There were 81 returned surveys from 46 transition and 35 non-transition patients. No statistically significant differences were found in disease burden, disease outcomes or adult roles and responsibilities between cohorts. Despite a high prevalence of mood disturbance (35%), there was a very low usage (5%) of psychological services in both cohorts. In the transition cohort, knowledge of their transition plan was reported by only 25/46 patients and the majority (54%) felt they were not strongly prepared. A high rate (78%) of discussion about work/study plans was recorded prior to transition, but a near complete absence of discussion regarding sex (8%), and other adult issues was recorded. Both cohorts agreed that their preferred method of future transition practices (of the options offered) was a shared clinic appointment with all key stakeholders. CONCLUSION: Transition did not appear to adversely affect disease or psychosocial outcomes. Current transition care processes could be optimised, with better psychosocial preparation and agreed transition plans

    Prognostic variables and scores identifying the end of life in COPD: a systematic review.

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    INTRODUCTION: COPD is a major cause of mortality, and the unpredictable trajectory of the disease can bring challenges to end-of-life care. We aimed to investigate known prognostic variables and scores that predict prognosis in COPD in a systematic literature review, specifically including variables that contribute to risk assessment of patients for death within 12 months. METHODS: We conducted a systematic review on prognostic variables, multivariate score or models for COPD. Ovid MEDLINE, EMBASE, the Cochrane database, Cochrane CENTRAL, DARE and CINAHL were searched up to May 1, 2016. RESULTS: A total of 5,276 abstracts were screened, leading to 516 full-text reviews, and 10 met the inclusion criteria. No multivariable indices were developed with the specific aim of predicting all-cause mortality in stable COPD within 12 months. Only nine indices were identified from four studies, which had been validated for this time period. Tools developed using expert knowledge were also identified, including the Gold Standards Framework Prognostic Indicator Guidance, the RADboud Indicators of Palliative Care Needs, the Supportive and Palliative Care Indicators Tool and the Necesidades Paliativas program tool. CONCLUSION: A number of variables contributing to the prediction of all-cause mortality in COPD were identified. However, there are very few studies that are designed to assess, or report, the prediction of mortality at or less than 12 months. The quality of evidence remains low, such that no single variable or multivariable score can currently be recommended

    DIALOGIC: A Core Natural-Language Processing System

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    The DIALOGIC system translates English sentences into representations of their literal meaning in the context of an utterance. These representations, or "logical forms," are intended to be a purely formal language that is as close as possible to the structure of natural language, while providing the semantic compositionality necessary for meaning-dependent computational processing. The design of DIALOGIC (and of its constituent modules) was influenced by the goal of using it as the core language-processing component in a variety of systems, some of which are transportable to new domains of application.Engineering and Applied Science
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