Vascular self-healing within carbon fibre reinforced polymer stringer run-out configurations

Stringer debonding within stiffened, assembled aerospace structures is one of the most critical damage scenarios that can occur in such structures. As a result, a degree of redundancy is inherently built-in to the design process of skin-stringer configurations to mitigate against premature and in-service failure. Introducing a “self-healing” solution for stringer run-out configurations has the benefit of mitigating and controlling damage initiation, and by introducing this concept there is great potential to reduce excessive conservative safety margins that could ultimately lead to more lightweight designs. Vascular self-healing technology has been successfully implemented into a simplified strap lap specimen, showing that the introduction of a vascular microchannel reduces the strength by 15% but has little effect on the stiffness. Upon delivery and cure of epoxy-based self-healing agents full recovery of the mechanical properties was observed. This self-healing approach has been further implemented into industrially relevant, larger stringer run-out panels as a feasibility study, in which no knockdown to mechanical properties caused by the embedded vascular microchannels has been observed, this study has also shown similar promising results in terms of performance recovery.</p

Optimisation of epoxy blends for use in extrinsic self-healing fibre-reinforced composites

AbstractA range of epoxy blends were investigated to determine their mechanical properties and suitability for use as healing agents for the repair of fibre-reinforced polymer (FRP) composites. Key requirements for an effective healing agent are low viscosity, and good mechanical performance. A base epoxy resin was selected and blended with a variety of diluents and a toughening agent, and the physical and mechanical properties of the resulting polymers were investigated. Single lap shear strengths of up to 139% of the base epoxy values were demonstrated, while double cantilever beam testing showed specimens healed with optimised epoxy blends can provide recoveries in fracture toughness of up to 269%, compared to 56% in specimens healed with the base epoxy resin. Cross-ply FRP laminate tensile specimens were used to highlight the potential to recover stiffness decay caused by intraply cracking. Following infusion of the damage via embedded vascules, the toughened epoxies were capable of providing complete recovery of stiffness

Identifying key influences on antibiotic use in China: a systematic scoping review and narrative synthesis

INTRODUCTION: The inappropriate use of antibiotics is a key driver of antimicrobial resistance. In China, antibiotic prescribing and consumption exceed recommended levels and are relatively high internationally. Understanding the influences on antibiotic use is essential to informing effective evidence-based interventions. We conducted a scoping review to obtain an overview of empirical research about key behavioural, cultural, economic and social influences on antibiotic use in China. METHODS: Searches were conducted in Econlit, Medline, PsycINFO, Social Science citation index and the Cochrane Database of Systematic Reviews for the period 2003 to early 2018. All study types were eligible including observational and intervention, qualitative and quantitative designs based in community and clinical settings. Two authors independently screened studies for inclusion. A data extraction form was developed incorporating details on study design, behaviour related to antibiotic use, influences on behaviour and information on effect (intervention studies only). RESULTS: Intervention studies increased markedly from 2014, and largely focused on the impact of national policy and practice directives on antibiotic use in secondary and tertiary healthcare contexts in China. Most studies used pragmatic designs, such as before and after comparisons. Influences on antibiotic use clustered under four themes: antibiotic prescribing; adherence to antibiotics; self-medicating behaviour and over-the-counter sale of antibiotics. Many studies highlighted the use of antibiotics without a prescription for common infections, which was facilitated by availability of left-over medicines and procurement from local pharmacies. CONCLUSIONS: Interventions aimed at modifying antibiotic prescribing behaviour show evidence of positive impact, but further research using more robust research designs, such as randomised trials, and incorporating process evaluations is required to better assess outcomes. The effect of national policy at the primary healthcare level needs to be evaluated and further exploration of the influences on antibiotic self-medicating is required to develop interventions that tackle this behaviour

Astrometric and Timing Effects of Gravitational Waves from Localized Sources

A consistent approach for an exhaustive solution of the problem of propagation of light rays in the field of gravitational waves emitted by a localized source of gravitational radiation is developed in the first post-Minkowskian and quadrupole approximation of General Relativity. We demonstrate that the equations of light propagation in the retarded gravitational field of an arbitrary localized source emitting quadrupolar gravitational waves can be integrated exactly. The influence of the gravitational field on the light propagation is examined not only in the wave zone but also in cases when light passes through the intermediate and near zones of the source. Explicit analytic expressions for light deflection and integrated time delay (Shapiro effect) are obtained accounting for all possible retardation effects and arbitrary relative locations of the source of gravitational waves, that of light rays, and the observer. It is shown that the ADM and harmonic gauge conditions can both be satisfied simultaneously outside the source of gravitational waves. Their use drastically simplifies the integration of light propagation equations and those for the motion of light source and observer in the field of the source of gravitational waves, leading to the unique interpretation of observable effects. The two limiting cases of small and large values of impact parameter are elaborated in more detail. Explicit expressions for Shapiro effect and deflection angle are obtained in terms of the transverse-traceless part of the space-space components of the metric tensor. We also discuss the relevance of the developed formalism for interpretation of radio interferometric and timing observations, as well as for data processing algorithms for future gravitational wave detectors.Comment: 43 pages, 4 Postscript figures, uses revtex.sty, accepted to Phys. Rev. D, minor corrections in formulae regarding algebraic sign

The impacts of environmental warming on Odonata: a review

Climate change brings with it unprecedented rates of increase in environmental temperature, which will have major consequences for the earth's flora and fauna. The Odonata represent a taxon that has many strong links to this abiotic factor due to its tropical evolutionary history and adaptations to temperate climates. Temperature is known to affect odonate physiology including life-history traits such as developmental rate, phenology and seasonal regulation as well as immune function and the production of pigment for thermoregulation. A range of behaviours are likely to be affected which will, in turn, influence other parts of the aquatic ecosystem, primarily through trophic interactions. Temperature may influence changes in geographical distributions, through a shifting of species' fundamental niches, changes in the distribution of suitable habitat and variation in the dispersal ability of species. Finally, such a rapid change in the environment results in a strong selective pressure towards adaptation to cope and the inevitable loss of some populations and, potentially, species. Where data are lacking for odonates, studies on other invertebrate groups will be considered. Finally, directions for research are suggested, particularly laboratory studies that investigate underlying causes of climate-driven macroecological patterns

Anti-cancer effects and mechanism of actions of aspirin analogues in the treatment of glioma cancer

INTRODUCTION: In the past 25 years only modest advancements in glioma treatment have been made, with patient prognosis and median survival time following diagnosis only increasing from 3 to 7 months. A substantial body of clinical and preclinical evidence has suggested a role for aspirin in the treatment of cancer with multiple mechanisms of action proposed including COX 2 inhibition, down regulation of EGFR expression, and NF-κB signaling affecting Bcl-2 expression. However, with serious side effects such as stroke and gastrointestinal bleeding, aspirin analogues with improved potency and side effect profiles are being developed. METHOD: Effects on cell viability following 24 hr incubation of four aspirin derivatives (PN508, 517, 526 and 529) were compared to cisplatin, aspirin and di-aspirin in four glioma cell lines (U87 MG, SVG P12, GOS – 3, and 1321N1), using the PrestoBlue assay, establishing IC50 and examining the time course of drug effects. RESULTS: All compounds were found to decrease cell viability in a concentration and time dependant manner. Significantly, the analogue PN517 (IC50 2mM) showed approximately a twofold increase in potency when compared to aspirin (3.7mM) and cisplatin (4.3mM) in U87 cells, with similar increased potency in SVG P12 cells. Other analogues demonstrated similar potency to aspirin and cisplatin. CONCLUSION: These results support the further development and characterization of novel NSAID derivatives for the treatment of glioma

Preliminary archaeoentomological analyses of permafrost-preserved cultural layers from the pre-contact Yup’ik Eskimo site of Nunalleq, Alaska : implications, potential and methodological considerations

Acknowledgements Site excavation and samples collection were conducted by archaeologists from the University of Aberdeen, with the help of archaeologists and student excavators from the University of Aberdeen University of Alaska Fairbanks and Bryn Mawr College, Kuskokwim Campus, College of Rural Alaska and residents of Quinhagak and Mekoryuk. This study is funded through AHRC grant to the project ‘Understanding Cultural Resilience and Climate Change on the Bering Sea through Yup’ik Ecological Knowledge, Lifeways, Learning and Archaeology’ to Rick Knecht, Kate Britton and Charlotta Hillderal (University of Aberdeen; AH/K006029/1). Thanks are due to Qanirtuuq Inc. and Quinhagak, Alaska for sampling permissions and to entomologists working at the CNC in Ottawa for allowing access to reference collections of beetles, lice and fleas. Yves Bousquet, Ales Smetana and Anthony E. Davies are specially acknowledged for their help with the identification of coleopteran specimens. Finally, we would also like to thank Scott Elias for useful comments on the original manuscript.Peer reviewedPublisher PD

Long-term effectiveness of tumour necrosis factor-α inhibitor treatment for psoriatic arthritis in the UK: A multicentre retrospective study

Objective. Real-world evidence of the long-term effectiveness of TNF-α inhibitor (TNFi) therapy in patients with PsA is limited. This study was conducted to describe patterns of TNFi therapy and treatment responses in patients with PsA treated in UK clinical practice. Methods. A multicentre, retrospective, observational cohort study of consenting patients treated with TNFi for PsA with ≥ 3 years follow-up from first TNFi initiation (observation period) was carried out in 11 UK National Health Service hospitals. Data were collected concerning baseline patient characteristics, PsA-related treatment pathways and TNFi treatment responses (PsA response criteria components: swollen/tender joint counts, physician and patient global assessments). Results. The mean age of patients (n=141) was 50.3 (S.D.: 12.1) years (50% male). During a median observation period of 4.5 (range: 3.4-5.5) years, patients received a median of one (range: one to five) TNFi. Twelve-week response rates for first TNFi (where available) were as follows: 80% (n=64/80) for swollen joint counts, 79% (n=63/79) for tender joint counts, 79% (n=37/47) for physician global assessments, 69% (n=41/59) for patient global assessments and 79% (n=37/47) for PsA response criteria. At the end of the observation period, the proportions of patients remaining on first, second, third and fourth/fifth TNFi were 56, 15, 5 and 3%, respectively; 21% of patients permanently discontinued TNFi therapy. Conclusion. Long-term TNFi therapy is generally well tolerated and may be effective; however, after initial TNFi failure, there appears to be progressively less benefit and more adverse effects with successive TNFi switches. Strategies are needed for effective therapy for PsA beyond the first TNFi failure

Consistent phenological shifts in the making of a biodiversity hotspot: the Cape flora

Background The best documented survival responses of organisms to past climate change on short (glacial-interglacial) timescales are distributional shifts. Despite ample evidence on such timescales for local adaptations of populations at specific sites, the long-term impacts of such changes on evolutionary significant units in response to past climatic change have been little documented. Here we use phylogenies to reconstruct changes in distribution and flowering ecology of the Cape flora - South Africa's biodiversity hotspot - through a period of past (Neogene and Quaternary) changes in the seasonality of rainfall over a timescale of several million years. Results Forty-three distributional and phenological shifts consistent with past climatic change occur across the flora, and a comparable number of clades underwent adaptive changes in their flowering phenology (9 clades; half of the clades investigated) as underwent distributional shifts (12 clades; two thirds of the clades investigated). Of extant Cape angiosperm species, 14-41% have been contributed by lineages that show distributional shifts consistent with past climate change, yet a similar proportion (14-55%) arose from lineages that shifted flowering phenology. Conclusions Adaptive changes in ecology at the scale we uncover in the Cape and consistent with past climatic change have not been documented for other floras. Shifts in climate tolerance appear to have been more important in this flora than is currently appreciated, and lineages that underwent such shifts went on to contribute a high proportion of the flora's extant species diversity. That shifts in phenology, on an evolutionary timescale and on such a scale, have not yet been detected for other floras is likely a result of the method used; shifts in flowering phenology cannot be detected in the fossil record

Comparative effectiveness of antihypertensive medication for primary prevention of cardiovascular disease: systematic review and multiple treatments meta-analysis

Background: We conducted a systematic review of evidence from randomized controlled trials to answer the following research question: What are the relative effects of different classes of antihypertensive drugs in reducing the incidence of cardiovascular disease outcomes for healthy people at risk of cardiovascular disease? Methods: We searched MEDLINE, EMBASE, AMED (up to February 2011) and CENTRAL (up to May 2009), and reference lists in recent systematic reviews. Titles and abstracts were assessed for relevance and those potentially fulfilling our inclusion criteria were then assessed in full text. Two reviewers made independent assessments at each step. We selected the following main outcomes: total mortality, myocardial infarction and stroke. We also report on angina, heart failure and incidence of diabetes. We conducted a multiple treatments meta-analysis using random-effects models. We assessed the quality of the evidence using the GRADE-instrument. Results: We included 25 trials. Overall, the results were mixed, with few significant dif-ferences, and with no drugclass standing out as superior across multiple outcomes. The only significant finding for total mortality based on moderate to high quality evidence was that beta-blockers (atenolol) were inferior to angiotensin receptor blockers (ARB) (relative risk (RR) 1.14; 95% credibility interval (CrI) 1.02 to 1.28). Angiotensin converting enzyme (ACE)- inhibitors came out inferior to calcium-channel blockers (CCB) regarding stroke-risk (RR 1.19; 1.03 to 1.38), but superior regarding risk of heart failure (RR 0.82; 0.69 to 0.94), both based on moderate quality evidence. Diuretics reduced the risk of myocardial infarction compared to beta-blockers (RR 0.82; 0.68 to 0.98), and lowered the risk of heart failure compared to CCB (RR 0.73; 0.62 to 0.84), beta-blockers (RR 0.73; 0.54 to 0.96), and alpha-blockers (RR 0.51; 0.40 to 0.64). The risk of diabetes increased with diuretics compared to ACE-inhibitors (RR 1.43; 1.12 to 1.83) and CCB (RR 1.27; 1.05 to 1.57). Conclusion: Based on the available evidence, there seems to be little or no difference between commonly used blood pressure lowering medications for primary prevention of cardiovascular disease. Beta-blockers (atenolol) and alpha-blockers may not be first-choice drugs as they were the only drug-classes that were not significantly superior to any other, for any outcomes