SWARM PARAMETERS IN ELECTRONEGATIVE GASES.

Uniform field steady state ionization growth currents are measured in SF(,6), N(,2) and SF(,6) + N(,2) mixtures over the E/p range 60-450 V cm(\u27-1) Torr(\u27-1). Analysis of ionization growth currents provided quantitative data on effective ionization, ionization and attachment coefficients. The variation of effective ionization coefficient in SF(,6) + N(,2) mixtures is found to be nonlinear with the percentage mixture ratio. It is observed that at a given electric field to gas pressure ratio, the effective ionization coefficient decreases with increasing SF(,6) component in the mixture. This reduction in the effective ionization coefficient becomes relatively higher as E/p decreases. However, once a certain concentration of SF(,6) in the mixture is reached, further addition of SF(,6) responds with relatively little effect on the reduction. The same behaviour is observed for spark over voltage measurements. Variation of spark over voltage with SF(,6) concentration shows saturation tendency particularly at high pd (cm-torr) levels. The data for effective ionization, ionization and attachment coefficients is also obtained in CCl(,2)F(,2) + CO(,2) electronegative gas mixtures where it is again observed that the variation of the effective ionization coefficient with respect to mixture percentage ratio is nonlinear at a given E/p in the interval 100 (LESSTHEQ) E/p (LESSTHEQ) 180 V cm(\u27-1) torr(\u27-1). A Monte-Carlo simulation technique is used to provide swarm data in SF(,6). The swarm parameters evaluated are compared with the experimental values of drift velocity, ratio of radial diffusion coefficient to mobility, ionization and attachment coefficients available in the literature. The electron-molecule collision cross sections adopted in the simulation resulted in good agreement with the experimental values over the E/p range of interest 100 (LESSTHEQ) E/p (LESSTHEQ) 180 V cm(\u27-1) Torr(\u27-1). The simulation is also extended to EXB uniform fields to observe the effect of perpendicularly applied magnetic fields on the swarm parameters of SF(,6).Dept. of Electrical and Computer Engineering. Paper copy at Leddy Library: Theses & Major Papers - Basement, West Bldg. / Call Number: Thesis1985 .D553. Source: Dissertation Abstracts International, Volume: 46-08, Section: B, page: 2753. Thesis (Ph.D.)--University of Windsor (Canada), 1985

Reducing the environmental impact of surgery on a global scale: systematic review and co-prioritization with healthcare workers in 132 countries

Abstract Background Healthcare cannot achieve net-zero carbon without addressing operating theatres. The aim of this study was to prioritize feasible interventions to reduce the environmental impact of operating theatres. Methods This study adopted a four-phase Delphi consensus co-prioritization methodology. In phase 1, a systematic review of published interventions and global consultation of perioperative healthcare professionals were used to longlist interventions. In phase 2, iterative thematic analysis consolidated comparable interventions into a shortlist. In phase 3, the shortlist was co-prioritized based on patient and clinician views on acceptability, feasibility, and safety. In phase 4, ranked lists of interventions were presented by their relevance to high-income countries and low–middle-income countries. Results In phase 1, 43 interventions were identified, which had low uptake in practice according to 3042 professionals globally. In phase 2, a shortlist of 15 intervention domains was generated. In phase 3, interventions were deemed acceptable for more than 90 per cent of patients except for reducing general anaesthesia (84 per cent) and re-sterilization of ‘single-use’ consumables (86 per cent). In phase 4, the top three shortlisted interventions for high-income countries were: introducing recycling; reducing use of anaesthetic gases; and appropriate clinical waste processing. In phase 4, the top three shortlisted interventions for low–middle-income countries were: introducing reusable surgical devices; reducing use of consumables; and reducing the use of general anaesthesia. Conclusion This is a step toward environmentally sustainable operating environments with actionable interventions applicable to both high– and low–middle–income countries

Delaying surgery for patients with a previous SARS-CoV-2 infection

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The impact of surgical delay on resectability of colorectal cancer: An international prospective cohort study

AimThe SARS-CoV-2 pandemic has provided a unique opportunity to explore the impact of surgical delays on cancer resectability. This study aimed to compare resectability for colorectal cancer patients undergoing delayed versus non-delayed surgery.MethodsThis was an international prospective cohort study of consecutive colorectal cancer patients with a decision for curative surgery (January-April 2020). Surgical delay was defined as an operation taking place more than 4 weeks after treatment decision, in a patient who did not receive neoadjuvant therapy. A subgroup analysis explored the effects of delay in elective patients only. The impact of longer delays was explored in a sensitivity analysis. The primary outcome was complete resection, defined as curative resection with an R0 margin.ResultsOverall, 5453 patients from 304 hospitals in 47 countries were included, of whom 6.6% (358/5453) did not receive their planned operation. Of the 4304 operated patients without neoadjuvant therapy, 40.5% (1744/4304) were delayed beyond 4 weeks. Delayed patients were more likely to be older, men, more comorbid, have higher body mass index and have rectal cancer and early stage disease. Delayed patients had higher unadjusted rates of complete resection (93.7% vs. 91.9%, P = 0.032) and lower rates of emergency surgery (4.5% vs. 22.5%, P ConclusionOne in 15 colorectal cancer patients did not receive their planned operation during the first wave of COVID-19. Surgical delay did not appear to compromise resectability, raising the hypothesis that any reduction in long-term survival attributable to delays is likely to be due to micro-metastatic disease

Outcomes from elective colorectal cancer surgery during the SARS‐CoV‐2 pandemic

Aim This study aimed to describe the change in surgical practice and the impact of SARS-CoV-2 on mortality after surgical resection of colorectal cancer during the initial phases of the SARS-CoV-2 pandemic. Method This was an international cohort study of patients undergoing elective resection of colon or rectal cancer without preoperative suspicion of SARS-CoV-2. Centres entered data from their first recorded case of COVID-19 until 19 April 2020. The primary outcome was 30-day mortality. Secondary outcomes included anastomotic leak, postoperative SARS-CoV-2 and a comparison with prepandemic European Society of Coloproctology cohort data. Results From 2073 patients in 40 countries, 1.3% (27/2073) had a defunctioning stoma and 3.0% (63/2073) had an end stoma instead of an anastomosis only. Thirty-day mortality was 1.8% (38/2073), the incidence of postoperative SARS-CoV-2 was 3.8% (78/2073) and the anastomotic leak rate was 4.9% (86/1738). Mortality was lowest in patients without a leak or SARS-CoV-2 (14/1601, 0.9%) and highest in patients with both a leak and SARS-CoV-2 (5/13, 38.5%). Mortality was independently associated with anastomotic leak (adjusted odds ratio 6.01, 95% confidence interval 2.58–14.06), postoperative SARS-CoV-2 (16.90, 7.86–36.38), male sex (2.46, 1.01–5.93), age >70 years (2.87, 1.32–6.20) and advanced cancer stage (3.43, 1.16–10.21). Compared with prepandemic data, there were fewer anastomotic leaks (4.9% versus 7.7%) and an overall shorter length of stay (6 versus 7 days) but higher mortality (1.7% versus 1.1%). Conclusion Surgeons need to further mitigate against both SARS-CoV-2 and anastomotic leak when offering surgery during current and future COVID-19 waves based on patient, operative and organizational risks