9095 research outputs found
Sort by
Synthesis of (+)-(R)-Tiruchanduramine
Get PDFThe absolute stereochemistry of the marine alkaloid (+)-(R)-tiruchanduramine was established via a convergent total synthesis in six steps and 15.5% overall yield from Fmoc-D-Dab(Boc)-OH
Multi-Constraint Gerchberg-Saxton Iteration Algorithms for Linearizing IM/DD Transmission Systems
Get PDFChromatic dispersion-enhanced signal-signal beating interference (SSBI) considerably affects the performance of intensity-modulation and direct-detection (IM/DD) fiber transmission systems. For recovering optical fields from received double sideband signals after propagating through IM/DD transmission systems, Gerchberg-Saxton (G-S) iterative algorithms are promising, which, however, suffers slow convergence speeds and local optimization problems. In this paper, we propose a multi-constraint iterative algorithm (MCIA) to extend the Gerchberg-Saxton-based linearized detection. The proposed technique can accelerate the convergence speed and realize nonlinear-equalization-free detection. Based on the data-aided iterative algorithm (DIA) and the decision-directed data-aided iterative algorithm (DD-DIA), the proposed technique reuses redundant bits from channel coding to not only correct decision errors but also enforce the constraints on the task function to further accelerate the whole optical field retrieval processing. Simulation results show that, compared with the DD-DIA, the MCIA reduces the received optical power (ROP) by about 1.5-dB for a 100-Gb/s over 50-km SSMF PAM-4 signal transmission at the SER of 2×10-2. For a 100-Gb/s over 400-km SSMF transmission system, just 30 MCIA iterations is needed, which is 30% reduction in iteration count compared with the DD-DIA. For further increased transmission capacities, the MCIA can improve the symbol error rate (SER) by two orders of magnitude compared with the conventional IA. To validate the effectiveness of the MCIA, we also conduct experiments to transmit 92-Gb/s PAM-4 signals over 50-km IM/DD fibre systems. We find that the MCIA has an 1-dB ROP improvement compared with the DD-DIA. Compared with Volterra nonlinear equalization, the BERs of the MCIA with a simple linear equalizer are reduced by more than one order of magnitude with only 52 MCIA iteration
The long life-time shadow of bullying: cost-effectiveness of KiVa to reduce bullying in primary schools
Get PDFBackgroundThe ‘long shadow’ of childhood bullying can extend beyond immediate adverse mental health and educational outcomes well into adulthood, with associated long-term health and social care costs. Reducing bullying is therefore a public health priority.KiVa, a school-based anti-bullying programme, is effective in reducing bullying in schools in Finland and is currently being tested in the UK through the large-scale Stand Together trial.MethodsThe Stand Together trial is a two-arm, pragmatic multicentre cluster randomised controlled trial (RCT) to test the effectiveness and cost-effectiveness of KiVa in reducing bullying in UK primary schools compared to usual practice over one academic year. The trial is targeting approximately 13,000 7- to 11-year-olds in 116 primary schools across England and Wales, including North Wales, the West Midlands, South East- and South West England. Usual practice is defined as the delivery of the Personal and Social Education (PSE) curriculum in Wales and the Personal, Social, Health and Economic (PSHE) Education in England.To assess cost-effectiveness, we are conducting a cost-utility analysis and wider cost-consequence analysis from a school and societal perspective. Pupil self-reported health-related quality of life (CHU9D) is the primary outcome to enable the calculation of quality-adjusted life years (QALYs) in an Incremental Cost Effectiveness Ratio (ICER). The cost-consequence analysis will consider other outcomes such as pupil self-reported bullying-victimisation, pupil absence and bullying-related service use, teacher wellbeing and the frequency of parent-school meetings regarding bullying
Winter inverse lake stratification under historic and future climate change
Get PDFMillions of lakes inversely stratify during winter. Seemingly subtle variations in the duration of winter stratification can have major ecological effects by, for example, altering the vertical distribution of oxygen and nutrients in lakes. Yet, the influence of climate change on winter stratification has been largely unexplored. To fill this knowledge gap, here we used a lake-climate model ensemble to investigate changes in winter stratification from 1901 to 2099 across 12,242 representative lakes situated throughout the Northern Hemisphere. By the end of the 21st century, winter stratification duration is projected to shorten by an average of 18.5–53.9 d under Representative Concentration Pathways (RCPs) 2.6–8.5. Projected changes are faster in warmer geographical regions, in which 35–69% of lakes will no longer inversely stratify by 2070–2099 under RCPs 2.6–8.5. This shortening and loss of winter stratification will likely have numerous implications for lakes, including the misalignment of lifecycle events causing shifts in biodiversity
One view is not enough: review of and encouragement for multiple and alternative representations in 3D and immersive visualisation
Get PDFThe opportunities for 3D visualisations are huge. People can be immersed inside their data, interface with it in natural ways, and see it in ways that are not possible on a traditional desktop screen. Indeed, 3D visualisations, especially those that are immersed inside head-mounted displays are becoming popular. Much of this growth is driven by the availability, popularity and falling cost of head-mounted displays and other immersive technologies. However, there are also challenges. For example, data visualisation objects can be obscured, important facets missed (perhaps behind the viewer), and the interfaces may be unfamiliar. Some of these challenges are not unique to 3D immersive technologies. Indeed, developers of traditional 2D exploratory visualisation tools would use alternative views, across a multiple coordinated view (MCV) system. Coordinated view interfaces help users explore the richness of the data. For instance, an alphabetical list of people in one view shows everyone in the database, while a map view depicts where they live. Each view provides a different task or purpose. While it is possible to translate some desktop interface techniques into the 3D immersive world, it is not always clear what equivalences would be. In this paper, using several case studies, we discuss the challenges and opportunities for using multiple views in immersive visualisation. Our aim is to provide a set of concepts that will enable developers to perform critical thinking, creative thinking and push the boundaries of what is possible with 3D and immersive visualisation. In summary developers should consider how to integrate many views, techniques and presentation styles, and one view is not enough when using 3D and immersive visualisations
Strategies for sample labelling and library preparation in DNA metabarcoding studies
Get PDFMetabarcoding of DNA extracted from environmental or bulk specimen samples is increasingly used to profile biota in basic and applied biodiversity research because of its targeted nature that allows sequencing of genetic markers from many samples in parallel. To achieve this, PCR amplification is carried out with primers designed to target a taxonomically informative marker within a taxonomic group, and sample-specific nucleotide identifiers are added to the amplicons prior to sequencing. The latter enables assignment of the sequences back to the samples they originated from. Nucleotide identifiers can be added during the metabarcoding PCR and during “library preparation”, that is, when amplicons are prepared for sequencing. Different strategies to achieve this labelling exist. All have advantages, challenges and limitations, some of which can lead to misleading results, and in the worst case compromise the fidelity of the metabarcoding data. Given the range of questions addressed using metabarcoding, ensuring that data generation is robust and fit for the chosen purpose is critically important for practitioners seeking to employ metabarcoding for biodiversity assessments. Here, we present an overview of the three main workflows for sample-specific labelling and library preparation in metabarcoding studies on Illumina sequencing platforms; one-step PCR, two-step PCR, and tagged PCR. Further, we distill the key considerations for researchers seeking to select an appropriate metabarcoding strategy for their specific study. Ultimately, by gaining insights into the consequences of different metabarcoding workflows, we hope to further consolidate the power of metabarcoding as a tool to assess biodiversity across a range of applications
Towards an Ecographics:Ecological Storylines in Bande dessinée
Get PDFWhat role do comics have to play in cultural conversations about and in the face of environmental collapse and mass extinction? This article takes bande dessinée as a case study to propose the concept of ecological storylines as part of an ecographics that recognises the specificities of comics as a drawn and narrative medium as well as its shifting place in culture. This is developed with reference to a range of graphic texts and along three axes. The article first explores drawing as material practice in ecographic engagements with radioactivity, gender and landscape. It then turns to redrawing as a mode of contestation as well as repair on a postcolonial planet, before closing with a discussion of flowlines across panels, pages, human and nonhuman bodies and across cityscapes, seascapes and petroscapes
Do banks fuel climate change?
Get PDFDo climate-oriented regulatory policies affect the flow of credit towards polluting firms? We match loan-level data to firm-level greenhouse gas emissions to assess the impact of the Paris Agreement. We find that, following this agreement, European banks reallocated credit away from polluting firms in relative terms. Specifically, euro area banks’ loan share to more polluting firms decreased by about 3 percentage points compared to less polluting (or “green”) firms after the 2015 Paris Agreement (COP21). This result is stronger for banks that are well capitalized, have lower credit quality, and are less profitable
Functionality screening to help design effective materials for radioiodine abatement
Get PDFThis paper is part of a growing body of research work looking at the synthesis of an optimal adsorbent for the capture and containment of aqueous radioiodine from nuclear fuel reprocessing waste. 32 metalated commercial ion exchange resins were subjected to a two-tier screening assessment for their capabilities in the uptake of iodide from aqueous solutions. The first stage determined that there was appreciable iodide capacity across the adsorbent range (12–220 mg·g−1). Candidates with loading capacities above 40 mg·g−1 were progressed to the second stage of testing, which was a fractional factorial experimental approach. The different adsorbents were treated as discrete variables and concentrations of iodide, co-contaminants and protons (pH) as continuous variables. This gave rise to a range of extreme conditions, which were representative of the industrial challenges of radioiodine abatement. Results were fitted to linear regression models, both for the whole dataset (R2 = 59%) and for individual materials (R2 = 18–82%). The overall model determined that iodide concentration, nitrate concentration, pH and interactions between these factors had significant influences on the uptake. From these results, the top six materials were selected for project progression, with others discounted due to either poor uptake or noticeable iodide salt precipitation behaviour. These candidates exhibited reasonable iodide uptake in most experimental conditions (average of >20 mg·g−1 hydrated mass), comparing favourably with literature values for metallated adsorbents. Ag-loaded Purolite S914 (thiourea functionality) was the overall best-performing material, although some salt precipitation was observed in basic conditions. Matrix effects not withstanding it is recommended that metalated thiourea, bispicolylamine, and aminomethylphosphonic acid functionalized silicas warrant further exploration
Exploring the impact of Covid-19 on the care and quality of life of people with dementia and their carers: A scoping review
Get PDFThis article reports on findings of a scoping review aimed to map the published literature concerning the impact of Covid-19 on the care and quality of life of people living with dementia and their carers. Twenty-nine articles were included in the review. Three overarching themes were identified: (1) Impact on people with dementia – unmet and increased care needs; (2) Impact on carers – increased stress and burden and (3) Impact according to demographics. Overall, findings show that Covid-19 has led to a reduction in support from health and social services and to a move towards technology-based support. Furthermore, Covid-19 has had a negative impact on the care and quality of life of people living with dementia and their carers, and that this impact was influenced by the severity of dementia