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66 result(s) for "Stevens, Emma R."
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Active eDNA Is More Cost‐Effective Than Fyke Nets or Passive eDNA Collection When Monitoring the Invasion of an Alien Freshwater Fish
Monitoring alien species is critical to their management. However, early detection of invading alien freshwater fish can be challenging due to the difficulty of observing fish in low abundance. Environmental DNA (eDNA) has emerged as a new and potentially more sensitive method for sampling invasive species as compared to conventional methods, but the comparative financial cost is not often assessed. Adoption of eDNA by managers requires studies that showcase its cost‐effectiveness relative to conventional approaches. Here we use eDNA to assist in the management of an aggressive alien fish, the pearl cichlid (Geophagus brasiliensis), that is invading an urban river in south‐western Australia. We applied an occupancy model to survey data collected 6 years apart (2015, 2021) to assess how the species' distribution had changed and to evaluate whether an instream barrier had the potential to limit upstream invasion. To understand the effectiveness of eDNA, we used our model to quantify the relative efficiency (capture probability) of two eDNA sampling methods (active eDNA and passive eDNA) and fyke netting, as well as the number of replicate samples required per site to deliver >95% detection. We coupled the number of replicates needed with the cost per replicate to determine the cost‐efficiency of each method. We found that G. brasiliensis abundance was higher in downstream reaches in both survey years, and there was no evidence that its distribution had changed through time. However, G. brasiliensis was present above the instream barrier. Active eDNA sampling was considerably better at detecting G. brasiliensis than the other methods, making it the most cost‐effective method. Fyke nets came in a close second, and passive eDNA was a very distant third. Our results directly inform management in the study river and broadly highlight the cost‐effectiveness of active eDNA as a freshwater biosecurity tool. Early detection of invading alien freshwater fish can be challenging due to the difficulty observing fish in low abundance. To understand the effectiveness of eDNA sampling, we used our model to quantify the relative efficiency of two eDNA sampling methods (active eDNA, passive eDNA) and fyke netting as well as the number of replicate samples required per site to deliver >95% detection. Active eDNA sampling was considerably better at detecting an invading fish than the other methods making it the most cost‐effective method.
Fishy Business—Assessing the Efficacy of Active and Passive eDNA to Describe the Fish Assemblage of a River in Southwestern Western Australia to Support Effective Monitoring
Worldwide, freshwater vertebrate populations are declining with increasing pressure on rivers due to numerous environmental and climatic threats. Environmental DNA (eDNA) could potentially provide a more efficient and non‐invasive mechanism to monitor freshwater systems, either as a complement or in replacement to traditional methods to accurately assess species' distributions. Here, we utilize a hierarchical multispecies N‐mixture model to compare three fish sampling methods: traditional fyke netting and active and passive environmental DNA sampling along a 30 km stretch of the Canning River in Western Australia. We used the fitted model to compare capture probabilities among sampling methods and reveal the sampling effort required to describe the species assemblage. Results indicated that while all methods could detect fish, combined eDNA methodologies detected one more fish species than those caught by fyke netting. In addition, active eDNA sampling produced the highest capture probabilities and more consistently described the entire fish assemblage at any given site. Fyke netting and passive eDNA did not show significant differences in their average capture probabilities, and both methods had lower abilities to capture individual species than active eDNA. Active eDNA also required fewer replicate samples to detect the expected observed richness, and fyke netting required the most replicates. Additionally, a hierarchical multispecies abundance model showed that active environmental DNA (eDNA) sampling is the most effective method for monitoring freshwater fish populations. This study contributes to our understanding of eDNA in aquatic systems and demonstrates that, at least under current conditions, active sampling is still the preferred method in freshwater systems with low flow compared to both passive sampling and fyke netting. This study compared three fish sampling methods: traditional fyke netting, and active and passive environmental DNA sampling along a 30 km stretch of the Canning River in Western Australia. The effectiveness of the three different methods of detecting fish was tested with a hierarchical multispecies abundance model fit, with the model used to estimate both detection probability and replication effort required. This study contributes to our understanding of eDNA in aquatic systems and demonstrates that, at least under current conditions, active sampling is still the preferred method in freshwater systems with low flow compared to both passive sampling and fyke netting.
Integrated reanalysis of global riverine fish eDNA datasets shows robustness and congruence of biodiversity conclusions
The analysis of environmental DNA (eDNA) has revolutionized biodiversity assessments in aquatic ecosystems, enabling non-invasive monitoring of fish communities across diverse regions. However, the global comparability of these eDNA datasets remains ambiguous due heterogeneous sampling protocols and bioinformatic workflows across studies, particularly regarding the robustness of their conclusions on biodiversity assessments. Here, we conducted a meta-analysis of 58 riverine fish eDNA metabarcoding datasets, covering 1,818 sampling sites worldwide, to evaluate the robustness of eDNA-derived biodiversity patterns. We found that species richness estimates and metrics of community structure derived under a common bioinformatic workflow were overall consistent with those of original analyses, despite the relatively high variability in bioinformatic analyses in the respective original studies. Contrastingly, congruence of species identity varied more extensively across datasets, mostly reflecting different completeness and regional relevance of reference databases. Restricting taxonomic assignment to basin-specific species pools improved species identification accuracy, while datasets lacking publicly accessible or well-curated reference data were more prone to mismatches. Year of sampling had a positive effect on taxonomic congruence, such that more recent studies showed increased robustness, also reflecting improved reference database coverage and enhanced species-level identification over time and overall method congruence in more recent years. Overall, the suitability and potential of eDNA for global biodiversity monitoring is corroborating overall robust biodiversity estimates, irrespective of the bioinformatic approaches. Our study underlines the effectiveness and need of further harmonization of bioinformatic workflows and strengthened region-specific reference databases for improved taxonomic resolution and comparability across studies.
Globally unified analysis of riverine eDNA reveals common associations of fish biodiversity with drainage characteristics
Freshwater biodiversity is declining at a pace that outstrips the capacity of existing monitoring approaches both in temporal and spatial dimensions, highlighting the urgent need for rapid and scalable assessment and attribution of biodiversity states and changes. Here, we present one of the first global assessments and unified analyses of riverine fish biodiversity using environmental DNA (eDNA) collected from 1818 sites across 113 river systems. We quantified species richness, functional redundancy, phylogenetic diversity, and genetic sequence diversity, and related them to drainage characteristics. Our results showed that eDNA effectively captured global patterns of multi-faceted riverine fish biodiversity and disentangled the roles of climate and human activities in shaping biodiversity–area relationships. Catchments in warmer climates consistently enhanced biodiversity accumulation with area, while higher human activity intensity weakened this scaling. Species richness, functional, and genetic sequence diversity exhibited stronger negative responses to human activities in larger catchments. In contrast, phylogenetic diversity showed the strongest negative effects in smaller catchments with these impacts diminishing as catchment area increased, highlighting the facet-dependent nature of biodiversity responses to environmental gradients. Our findings demonstrate the power of eDNA-based datasets for harmonized, multi-faceted biodiversity assessments, offering a scalable approach for detecting and attributing biodiversity change and informing conservation strategies under accelerating global change.
In Vivo Assessment of Bone Regeneration in Alginate/Bone ECM Hydrogels with Incorporated Skeletal Stem Cells and Single Growth Factors
The current study has investigated the use of decellularised, demineralised bone extracellular matrix (ECM) hydrogel constructs for in vivo tissue mineralisation and bone formation. Stro-1-enriched human bone marrow stromal cells were incorporated together with select growth factors including VEGF, TGF-β3, BMP-2, PTHrP and VitD3, to augment bone formation, and mixed with alginate for structural support. Growth factors were delivered through fast (non-osteogenic factors) and slow (osteogenic factors) release PLGA microparticles. Constructs of 5 mm length were implanted in vivo for 28 days within mice. Dense tissue assessed by micro-CT correlated with histologically assessed mineralised bone formation in all constructs. Exogenous growth factor addition did not enhance bone formation further compared to alginate/bone ECM (ALG/ECM) hydrogels alone. UV irradiation reduced bone formation through degradation of intrinsic growth factors within the bone ECM component and possibly also ECM cross-linking. BMP-2 and VitD3 rescued osteogenic induction. ALG/ECM hydrogels appeared highly osteoinductive and delivery of angiogenic or chondrogenic growth factors led to altered bone formation. All constructs demonstrated extensive host tissue invasion and vascularisation aiding integration and implant longevity. The proposed hydrogel system functioned without the need for growth factor incorporation or an exogenous inducible cell source. Optimal growth factor concentrations and spatiotemporal release profiles require further assessment, as the bone ECM component may suffer batch variability between donor materials. In summary, ALG/ECM hydrogels provide a versatile biomaterial scaffold for utilisation within regenerative medicine which may be tailored, ultimately, to form the tissue of choice through incorporation of select growth factors.
Percutaneous tibial nerve stimulation versus sham electrical stimulation for the treatment of faecal incontinence in adults (CONFIDeNT): a double-blind, multicentre, pragmatic, parallel-group, randomised controlled trial
Percutaneous tibial nerve stimulation (PTNS) is a new ambulatory therapy for faecal incontinence. Data from case series suggest it has beneficial outcomes in 50–80% patients; however its effectiveness against sham electrical stimulation has not been investigated. We therefore aimed to assess the short-term efficacy of PTNS against sham electrical stimulation in adults with faecal incontinence. We did a double-blind, multicentre, pragmatic, parallel-group, randomised controlled trial (CONtrol of Faecal Incontinence using Distal NeuromodulaTion [CONFIDeNT]) in 17 specialist hospital units in the UK that had the skills to manage patients with faecal incontinence. Eligible participants aged 18 years or older with substantial faecal incontinence for whom conservative treatments (such as dietary changes and pelvic floor exercises) had not worked, were randomly assigned (1:1) to receive either PTNS (via the Urgent PC neuromodulation system) or sham stimulation (via a transcutaneous electrical nerve stimulation machine to the lateral forefoot) once per week for 12 weeks. Randomisation was done with permuted block sizes of two, four, and six, and was stratified by sex and then by centre for women. Patients and outcome assessors were both masked to treatment allocation for the 14-week duration of the trial (but investigators giving the treatment were not masked). The primary outcome was a clinical response to treatment, which we defined as a 50% or greater reduction in episodes of faecal incontinence per week. We assessed this outcome after 12 treatment sessions, using data from patients' bowel diaries. Analysis was by intention to treat, and missing data were multiply imputed. This trial is registered with the ISRCTN registry, number 88559475, and is closed to new participants. Between Jan 23, 2012, and Oct 31, 2013, we randomly assigned 227 eligible patients (of 373 screened) to receive either PTNS (n=115) or sham stimulation (n=112). 12 patients withdrew from the trial: seven from the PTNS group and five from the sham group (mainly because they could not commit to receiving treatment every week). Two patients (one in each group) withdrew because of an adverse event that was unrelated to treatment (exacerbation of fibromyalgia and rectal bleeding). 39 (38%) of 103 patients with full data from bowel diaries in the PTNS group had a 50% or greater reduction in the number of episodes of faecal incontinence per week compared with 32 (31%) of 102 patients in the sham group (adjusted odds ratio 1·28, 95% CI 0·72–2·28; p=0·396). No serious adverse events related to treatment were reported in the trial. Seven mild, related adverse events were reported in each treatment group, mainly pain at the needle site (four in PTNS, three in sham). PTNS given for 12 weeks did not confer significant clinical benefit over sham electrical stimulation in the treatment of adults with faecal incontinence. Further studies are warranted to determine its efficacy in the long term, and in patient subgroups (ie, those with urgency). National Institute for Health Research.
Effects of Aspirin for Primary Prevention in Persons with Diabetes Mellitus
A multicenter, randomized trial involving participants with diabetes and no evident cardiovascular disease at trial entry showed that aspirin led to a lower risk of serious vascular events than placebo but also caused a higher risk of major bleeding.
Effects of n−3 Fatty Acid Supplements in Diabetes Mellitus
In this trial involving patients with diabetes without evidence of cardiovascular disease, the risk of serious vascular events was similar in those who received n−3 fatty acid supplements and those who received placebo.
Cost-effectiveness of laparoscopic ileocaecal resection versus infliximab treatment of terminal ileitis in Crohn’s disease: the LIR!C Trial
ObjectiveEvaluate the cost-effectiveness of laparoscopic ileocaecal resection compared with infliximab in patients with ileocaecal Crohn’s disease failing conventional therapy.DesignA multicentre randomised controlled trial was performed in 29 centres in The Netherlands and the UK. Adult patients with Crohn’s disease of the terminal ileum who failed >3 months of conventional immunomodulators or steroids without signs of critical strictures were randomised to laparoscopic ileocaecal resection or infliximab. Outcome measures included quality-adjusted life-years (QALYs) based on the EuroQol (EQ) 5D-3L Questionnaire and the Inflammatory Bowel Disease Questionnaire (IBDQ). Costs were measured from a societal perspective. Analyses were performed according to the intention-to-treat principle. Missing cost and effect data were imputed using multiple imputation. Cost-effectiveness planes and cost-effectiveness acceptability curves were estimated to show uncertainty.ResultsIn total, 143 patients were randomised. Mean Crohn’s disease total direct healthcare costs per patient at 1 year were lower in the resection group compared with the infliximab group (mean difference €−8931; 95% CI €−12 087 to €−5097). Total societal costs in the resection group were lower than in the infliximab group, however not statistically significant (mean difference €−5729, 95% CI €−10 606 to €172). The probability of resection being cost-effective compared with infliximab was 0.96 at a willingness to pay (WTP) of €0 per QALY gained and per point improvement in IBDQ Score. This probability increased to 0.98 at a WTP of €20 000/QALY gained and 0.99 at a WTP of €500/point of improvement in IBDQ Score.ConclusionLaparoscopic ileocaecal resection is a cost-effective treatment option compared with infliximab.Clinical trial registration numberDutch Trial Registry NTR1150; EudraCT number 2007-005042-20 (closed on 14 October 2015).
Carbon-rich Dust Injected into the Interstellar Medium by Galactic WC Binaries Survives for Hundreds of Years
Some carbon-rich Wolf–Rayet (WC) stars show an infrared excess from dust emission (WCd stars). Dust forms in the collision of the WC wind with a companion star’s wind. As this dust is carried toward the interstellar medium (ISM) at close to the WCd wind speed and the binary continues through its orbit, a spiral structure forms around the system. The shape depends on the orbital eccentricity and period, as well as stellar parameters like mass-loss rates and terminal wind speeds. Imaging of the WCd binary WR 140 with JWST/MIRI revealed 17 concentric dust shells surrounding the binary. We present new JWST imaging of four additional WCd systems (WR 48a, WR 112, WR 125, and WR 137) that were imaged in 2024. In this analysis, we show that the dust is long-lived, detected with an age of at least 130 yr, but more than 300 yr in some systems. Longer-duration measurements are limited by sensitivity. Regular spacing of dust features confirms the periodic nature of dust formation, consistent with a connection to binary motion. We use these images to estimate the proper motion of the dust, finding the dust to propagate out to the ISM with motion comparable to the wind speed of the WC stars. In addition to these results, we observe unusual structures around WR 48a, which could represent dusty clumps shaped by photoevaporation and wind ablation like young proplyd objects. These results demonstrate that WC dust is indeed long-lived and should be accounted for in galactic dust budgets.