97 research outputs found

    Effects of Trophic Skewing of Species Richness on Ecosystem Functioning in a Diverse Marine Community

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    Widespread overharvesting of top consumers of the world’s ecosystems has “skewed” food webs, in terms of biomass and species richness, towards a generally greater domination at lower trophic levels. This skewing is exacerbated in locations where exotic species are predominantly low-trophic level consumers such as benthic macrophytes, detritivores, and filter feeders. However, in some systems where numerous exotic predators have been added, sometimes purposefully as in many freshwater systems, food webs are skewed in the opposite direction toward consumer dominance. Little is known about how such modifications to food web topology, e.g., changes in the ratio of predator to prey species richness, affect ecosystem functioning. We experimentally measured the effects of trophic skew on production in an estuarine food web by manipulating ratios of species richness across three trophic levels in experimental mesocosms. After 24 days, increasing macroalgal richness promoted both plant biomass and grazer abundance, although the positive effect on plant biomass disappeared in the presence of grazers. The strongest trophic cascade on the experimentally stocked macroalgae emerged in communities with a greater ratio of prey to predator richness (bottom-rich food webs), while stronger cascades on the accumulation of naturally colonizing algae (primarily microalgae with some early successional macroalgae that recruited and grew in the mesocosms) generally emerged in communities with greater predator to prey richness (the more top-rich food webs). These results suggest that trophic skewing of species richness and overall changes in food web topology can influence marine community structure and food web dynamics in complex ways, emphasizing the need for multitrophic approaches to understand the consequences of marine extinctions and invasions

    Are identities oral? Understanding ethnobotanical knowledge after Irish independence (1937-1939)

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    BACKGROUND: The Schools' Folklore Scheme (1937-1939) was implemented at a pivotal time in Irelands' political history. It resulted in a body of ethnological information that is unique in terms of when, why and how it was collected. This material consists of over 700,000 pages of information, including ethnomedicinal and ethnobotanical traditions, reflecting an oral identity that spans generations and that in many cases was not documented in writing until the 1930s. The intention of this study is to highlight the importance of the Schools' Folklore Scheme and to demonstrate an ethnographic approach based on recollections of original participants of the scheme, to further understand the material in the collection and the impact it had on the participants. METHODS: This study involves an analysis of both oral and archival data. Eleven semi-structured interviews with original participants of the scheme were carried out between April and September 2016. Their corresponding schools' archival contributions to the scheme were located, and ethnomedicinal information was analysed and compared with the participants' recollections. RESULTS: The majority of participants' stated the scheme had a positive impact on them. Five participants' recalled collecting ethnomedicinal information, and there was a direct correlation between three of the participants' ethnomedicinal recollections and their entries in the archives. One third of all the ethnomedicinal entries analysed included the use of a plant. There were 191 plant mentions and 64 plant species named. CONCLUSIONS: Contacting the original participants offers a novel approach of analysing this archival material. It provides a unique first-hand account of this historical initiative, an insight into how the scheme was implemented and how it impacted upon the children. The ethnomedicinal and ethnobotanical information provides an understanding of the medicinal practices in Ireland during the 1930s. The plant species that were both orally recalled by participants and documented in the archives are in keeping with key ethnomedicinal systems throughout the world

    Analytical Solution for Extensible Tethers

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    Wobble Correction for a Dual-Spin Vehicle

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    The acceptability to patients of computerized cognitive behaviour therapy for depression : a systematic review

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    Background Cognitive behaviour therapy (CBT) is widely used to treat depression. However, CBT is not always available to patients because of a shortage of therapists and long waiting times. Computerized CBT (CCBT) is one of several alternatives currently available to treat patients with depression. Evidence of its clinical effectiveness has led to programs being used increasingly within the UK and elsewhere. However, little information is available regarding the acceptability of CCBT to patients. Method A systematic review of sources of information on acceptability to patients of CCBT for depression. Results Sources of information on acceptability included: recruitment rates, patient drop-outs and patient-completed questionnaires. We identified 16 studies of CCBT for the treatment of depression that provided at least some information on these sources. Limited information was provided on patient take-up rates and recruitment methods. Drop-out rates were comparable to other forms of treatment. Take-up rates, when reported, were much lower. Six of the 16 studies included specific questions on patient acceptability or satisfaction although information was only provided for those who had completed treatment. Several studies have reported positive expectancies and high satisfaction in routine care CCBT services for those completing treatment. Conclusions Trials of CCBT should include more detailed information on patient recruitment methods, drop-out rates and reasons for dropping out. It is important that well-designed surveys and qualitative studies are included alongside trials to determine levels and determinants of patient acceptability

    Computerised cognitive behaviour therapy for depression and anxiety update: a systematic review and economic evaluation

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    Objectives: To evaluate computerised cognitive behaviour therapy (CCBT) for the treatment of anxiety, depression, phobias, panic and obsessive–compulsive behaviour (OCD). The software packages to be considered include Beating the Blues (BtB), Overcoming Depression: a five areas approach, FearFighter (FF), Cope and BT Steps. Other packages or programmes incorporating CCBT were also considered. Data sources: Electronic databases from 1966 to March 2004. Evidence submitted by sponsors for CCBT products. Review methods: A systematic review was performed to identify all studies describing trials of CCBT. The costeffectiveness assessment included a review of the literature and the evidence submitted by sponsors for each of the products. A series of cost-effectiveness models was developed and run by the project team for the five CCBT products across the three mental health conditions. Results: Twenty studies were identified in the clinical effectiveness review. The analysis of these results showed some evidence that CCBT is as effective as therapist-led cognitive behaviour therapy (TCBT) for the treatment of depression/anxiety and phobia/panic and is more effective than treatment as usual (TAU) in the treatment of depression/anxiety. CCBT also appears to reduce therapist time compared with TCBT. When reviewing cost-effectiveness studies, only one published economic evaluation of CCBT was found. This was an economic evaluation of the depression software BtB alongside a randomised controlled trial (RCT), which found that BtB was cost-effective against TAU in terms of cost per quality-adjusted life-year (QALY) (less than £2000), however it contained weaknesses that were then addressed in the costeffectiveness model developed for the study. The results of the model for the depression software packages in terms of incremental cost per QALY compared with TAU and the chance of being costeffective at £30,000 per QALY were for BtB £1801 and 86.8%, for Cope £7139 and 62.6% and for Overcoming Depression £5391 and 54.4%. The strength of the BtB software being that it has been evaluated in the context of an RCT with a control group. The subgroup analysis found no differences across the severity groupings. For phobia/panic software, the model showed an incremental cost per QALY of FF over relaxation was £2380. Its position compared with TCBT is less clear. When modelling OCD packages, using the practice-level licence cost meant that BT Steps was dominated by TCBT, which had significantly better outcomes and was cheaper. However, the cheaper PCT licence resulted in the incremental cost-effectiveness of BT Steps over relaxation being £15,581 and TCBT over BT Steps being £22,484. Conclusions: The study findings are subject to substantial uncertainties around the organisational level for purchasing these products and the likely throughput. This is in addition to concerns with the quality of evidence on response to therapy, longer term outcomes and quality of life. The position of CCBT within a stepped care programme needs to be identified, as well as its relationship to other efforts to increase access to CBT and psychological therapies. Research is needed to compare CCBT with other therapies that reduce therapist time, in particular bibliotherapy and to explore the use of CCBT via the Internet. Independent research is needed, particularly RCTs, that examine areas such as patient preference and therapist involvement within primary care
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