A new mixing technique for randomly distributed fibre-reinforced expansive soil

In the state of Gujarat, India, a significant part of the area is covered by expansive soil deposits. The swelling and shrinkage characteristics of expansive soil as a result of wetting and drying cause problems for safety and/or performance of structures. The concept of reinforcing soil with fibres, resulting in a randomly distributed fibre-reinforced soil (RDFS), has been studied in significant details, especially for reinforcing granular soils. Studies on fibre-reinforced expansive soils as reported in the literature are very limited. One of the major problems in the study of fibre-reinforced expansive soils is how to mix fibres uniformly. Therefore, the main objective of this paper is to study the available mixing methods, assess their suitability and develop a new mixing technique, which will be cost-effective for mixing fibres with expansive soil, especially in developing countries. In the present study, a surface modification method with cement has been proposed, where the waste tyre fibres (WTFs) were coated with cement to improve the bonding between fibres and clay minerals. The effect of this modification on the strength property of reinforced soil has been examined with unconfined compressive strength analysis. The results show that the shear strength between cement coated fibres and soil is significantly higher than the shear strength between fibres and natural soil

Effect of general anaesthesia on functional outcome in patients with anterior circulation ischaemic stroke having endovascular thrombectomy versus standard care: a meta-analysis of individual patient data

Background: General anaesthesia (GA) during endovascular thrombectomy has been associated with worse patient outcomes in observational studies compared with patients treated without GA. We assessed functional outcome in ischaemic stroke patients with large vessel anterior circulation occlusion undergoing endovascular thrombectomy under GA, versus thrombectomy not under GA (with or without sedation) versus standard care (ie, no thrombectomy), stratified by the use of GA versus standard care. Methods: For this meta-analysis, patient-level data were pooled from all patients included in randomised trials in PuMed published between Jan 1, 2010, and May 31, 2017, that compared endovascular thrombectomy predominantly done with stent retrievers with standard care in anterior circulation ischaemic stroke patients (HERMES Collaboration). The primary outcome was functional outcome assessed by ordinal analysis of the modified Rankin scale (mRS) at 90 days in the GA and non-GA subgroups of patients treated with endovascular therapy versus those patients treated with standard care, adjusted for baseline prognostic variables. To account for between-trial variance we used mixed-effects modelling with a random effect for trials incorporated in all models. Bias was assessed using the Cochrane method. The meta-analysis was prospectively designed, but not registered. Findings: Seven trials were identified by our search; of 1764 patients included in these trials, 871 were allocated to endovascular thrombectomy and 893 were assigned standard care. After exclusion of 74 patients (72 did not undergo the procedure and two had missing data on anaesthetic strategy), 236 (30%) of 797 patients who had endovascular procedures were treated under GA. At baseline, patients receiving GA were younger and had a shorter delay between stroke onset and randomisation but they had similar pre-treatment clinical severity compared with patients who did not have GA. Endovascular thrombectomy improved functional outcome at 3 months both in patients who had GA (adjusted common odds ratio (cOR) 1·52, 95% CI 1·09–2·11, p=0·014) and in those who did not have GA (adjusted cOR 2·33, 95% CI 1·75–3·10, p<0·0001) versus standard care. However, outcomes were significantly better for patients who did not receive GA versus those who received GA (covariate-adjusted cOR 1·53, 95% CI 1·14–2·04, p=0·0044). The risk of bias and variability between studies was assessed to be low. Interpretation: Worse outcomes after endovascular thrombectomy were associated with GA, after adjustment for baseline prognostic variables. These data support avoidance of GA whenever possible. The procedure did, however, remain effective versus standard care in patients treated under GA, indicating that treatment should not be withheld in those who require anaesthesia for medical reasons