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Background Competency-based medical education has renewed focus on the attainment and evaluation of resident skill. Proper evaluation is crucial to inform educational interventions and identify residents in need of increased training and supervision. Currently, there is a paucity of studies rigorously evaluating resident chest tube insertion skill. Materials and methods Residents of all training levels before their intensive care unit rotation or currently rotating through the intensive care unit were invited to participate. Trainees inserted a thoracostomy tube on a high-fidelity simulator. Their performances were recorded and scored by blinded raters using the validated TUBE-iCOMPT rubric. Surgical and nonsurgical residents were compared. Results Forty-nine residents participated; 30 from nonsurgical and 19 from surgical training programs. Overall, trainees were most deficient in the “preprocedural checks” and “patient positioning and local anesthetic” domains. Surgical trainees demonstrated higher chest tube insertion skill than their nonsurgical peers (median total score 88 [interquartile range, 74-90] versus 75 [interquartile range, 66-85], respectively, P = 0.01), particularly in the “patient positioning” and “blunt dissection” domains (P = 0.01 and P = 0.03, respectively). These differences were no longer significant when controlled for experience and Advanced Trauma Life Support certification. Conclusions Overall, surgical residents were more skilled than nonsurgical residents in tube thoracostomy placement. Relative skill deficits within the domains of chest tube insertion have also been identified among residents of different specialties. These areas can be targeted with educational interventions to improve resident performance, and ultimately, patient safety.

We investigated the yield of ultrasound surveillance for small abdominal aortic aneurysms (AAAs) in patients older than 80 years compared with a younger population for detecting AAA growth reaching the threshold size for repair. Secondary objectives included analysis of the incidence of AAA repair and the cost-benefit of surveillance.A retrospective cohort study was performed of all patients undergoing AAA surveillance in Ottawa between 2007 and 2015. Patients were dichotomized by enrollment age (80 years vs ≥80 years) and stratified by enrollment AAA size. Cohorts were cross-referenced with the Ottawa surgical database, leveraging the common health region to ensure complete data capture. The threshold size for repair was sex specific (female, 5.0 cm; male, 5.5 cm). Factors influencing AAA growth rate were assessed with a general linear multiple mixed model. Analyses with Cox proportional hazards models with competing risk for mortality assessed aorta-related events, and cost-benefit was analyzed by referencing Ontario billing codes.A total of 1231 patients underwent serial ultrasound surveillance, of whom 500 were older than 80 years at some point during the study period. The mean AAA growth rate was 1.63 mm/y (95% confidence interval [CI], 1.54-1.71). Old age and small enrollment aneurysm size were significantly protective against AAA growth. Overall, 357 (29%) patients reached the AAA size threshold for repair, and 272 (22%) underwent AAA repair. Patients older than 80 years were less likely to reach the AAA threshold size for repair compared with their younger counterparts (adjusted hazard ratio, 0.77; 95% CI, 0.61-0.97). Of the 357 patients whose AAA reached the threshold size for repair, octogenarians were substantially less likely to undergo elective AAA repair (adjusted hazard ratio, 0.34; 95% CI, 0.24-0.47). Repair of ruptured AAA was rare (0.8%), and age differences were insignificant. For every octogenarian with an enrollment AAA size between 3.0 and 3.9 cm who ultimately received elective AAA repair, 51 patients were enrolled in surveillance without elective repair. This corresponded to an estimated $33,139 in ultrasound fees.Surveillance of most patients with small AAA is appropriate. However, patients older than 80 years were significantly less likely than their younger counterparts to experience aortic growth reaching the threshold size for repair. Furthermore, in the unlikely event of AAA growth, patients older than 80 years were substantially less likely to undergo repair. These results suggest that in the context of patient-specific health and wishes, surveillance of AAAs 4 cm in octogenarians is costly and unlikely to be beneficial.

Objectives Patients with infrainguinal peripheral arterial disease often undergo multiple revascularisation procedures. Although many centres have adopted an endovascular first approach, some are reluctant to do so for fear of compromising the outcomes of any subsequent bypasses. All studies that compared the outcomes of primary infrainguinal bypass with bypass after failed endovascular intervention were analysed. Methods A systematic review was conducted of MEDLINE, EMBASE, and CENTRAL databases for studies comparing outcomes of primary infrainguinal bypass with bypass after failed endovascular intervention for peripheral arterial disease. Abstracts and full text studies were screened independently by two reviewers with data abstraction done in duplicate. Dichotomous outcome measures were reported using the OR and 95% CI, and pooled using random effects models. Results Abstracts were screened (2,528), with 50 selected for full text review. Of these, 15 studies involving 11,886 patients met the inclusion criteria. Pooling the results of studies comparing primary bypass with bypass after failed endovascular intervention showed no significant difference in 30 day mortality (OR 1.00; 95% CI 0.65–1.54), or 30 day amputation rates (OR 1.26; 95% CI 0.95–1.65). Interestingly, one year amputation free survival was higher in the patients who had primary bypass (OR 1.30; 95% CI 1.10–1.52) compared with patients who had bypass after failed endovascular therapy. There was also worse one year primary patency (OR 1.65; 95% CI 1.04–2.62) for patients with prior failed endovascular intervention. The review demonstrated a trend towards higher rates of early graft occlusion (OR 4.54; 95% CI 0.97–21.28). Conclusions Meta-analysis of the existing literature comparing primary bypass with bypass following failed endovascular intervention shows worse one year amputation free survival and worse primary patency in those patients who undergo bypass after failed endovascular intervention. There is also a trend towards higher rates of early graft occlusion, although these results were not statistically significant. These conclusions are limited by observational study design, inconsistent patient selection, and significant heterogeneity between studies.

In this work, we demonstrate that a new mechanical attrition process can be used to prepare nanosilicon powder from metallurgical grade silicon lumps. Composite Li-ion anode made from this nanometer-size powder was found to have a high reversible capacity of 2400 mAh g −1 and an improved cycling stability compared to micrometer-sized powder. It is proposed that improved battery cycling performance is ascribed to the nanoscale silicon particles which supresses the volume expansion owing to its superplasticity.

Composite Li-ion anode can be fabricated using silicon nanopowders synthesized by induced plasma atomization. Properties of such nanopowder were characterized by physical and electrochemical methods. Primary particles were crystalline with spherical shape and the typical diameter ranging from 50 to 200 nm. The Si nanopowder showed a high gravimetric capacity (4900 mAh/g) at first discharge and around 12% irreversible loss of lithium. In addition, observations of a single silicon particle made by in situ TEM permitted to compare the volume change during lithiation with other silicon anode nanomaterials.

Compression molding of randomly oriented strands (ROS) composites offers the possibility to manufacture complex parts with a fast processing cycle. In this paper, effects of pressure, strand size, temperature, and material placement in the mold cavity on the quality of a T-shape part were studied experimentally with carbon/polyether ether ketone ROS composites. Minimum filling pressure was obtained for the consolidation of a 25-mm deep cavity. Parts processed at filling pressure showed a void content no greater than 1.2%. Increasing pressure to 70 bar resulted in decreased void content as low as 0.03%. Mechanical testing of the T-shape showed similar strengths for parts processed at filling pressure and higher (70 bar). At the component level, initial strand placement greatly affected mechanical performance as the presence of a knit line was responsible for a reduction of 60% in tensile strength. The main findings show that processing a complex feature at filling pressure Pfill was sufficient to reach nominal mechanical properties. This suggested that moderate porosity was not detrimental to the mechanical performance for the given tests where fatigue performance was not evaluated.

Models establishing relationships between electrical resistivity and dopant densities of silicon wafers/bricks are not applicable for compensated-Si, such as upgraded metallurgical grade silicon UMG-Si. To date, no satisfactory theoretical model has been able to explain precisely the variety of new experimental results and observations related to compensated-Si. In this study, a new approach considering equilibrium ionisation constants according to electrolyte theory was proposed, which reproduce, for single-doped Si, Thurber's curves of charge carrier's mobilities. When more than one doping species are involved, as in compensated-Si, a numerical algorithm has to be used for solving multiple equilibrium systems. The study of such systems demonstrates a particular behaviour known from buffered solutions. Equilibrium constants were calculated from thermodynamic properties of chemical compounds, and a new general theory was proposed using available knowledge of electrochemistry (Nernst equation, Butler-Volmer equation). Considering that the silicon/dopant systems constitute a weak electrolyte solid solution, it is concluded that the electrolyte solution theory provides a good physical model and mathematical framework to get a better understanding of solar cell's behaviour.

Objective Patient-based decision aids and other multimedia tools have been developed to help enrich the preoperative discussion between surgeon and patient. Use of these tools, however, can be time-consuming and logistically challenging. We investigated whether simply showing patients their images from preoperative computed tomography (CT) or angiography would improve patients' satisfaction with the preoperative discussion. We also examined whether this improved the patient's understanding and trust and whether it contributed to increased preoperative anxiety. Methods Patients undergoing either elective abdominal aortic aneurysm repair or lower limb revascularization were randomly assigned to either standard perioperative discussion or perioperative discussion and review of images (CT image or angiogram). Randomization was concealed and stratified by surgeon. Primary outcome was patient satisfaction with the preoperative discussion as measured by a validated 7-item scale (score, 0-28), with higher scores indicating improved satisfaction. Secondary outcomes included patient understanding, patient anxiety, patient trust, and length of preoperative discussion. Scores were compared using t-test. Results Overall, 51 patients were randomized, 25 to the intervention arm (discussion and imaging) and 26 to the control arm. Most patients were male (69%), and the average age was 70 years. Forty percent of patients underwent abdominal aortic aneurysm repair, whereas 60% underwent lower limb revascularization. Patient satisfaction with the discussion was generally high, with no added improvement when preoperative images were reviewed (mean score, 24.9 ± 3.02 vs 24.8 ± 2.93; P = .88). Similarly, there was no difference in the patient's anxiety, level of trust, or understanding when the imaging review was compared with standard discussion. There was a trend toward longer preoperative discussions in the group that underwent imaging review (8.18 vs 6.35 minutes; P = .07). Conclusions Showing patients their CT or angiography images during the preoperative discussion does not improve the patient's satisfaction with the consent discussion. Similarly, there was no effect on the patient's trust, understanding, or anxiety level. Our conclusions are limited by the lack of a standardized measure of patient understanding and not measuring outcomes postoperatively, both of which should be considered in future studies.