Damage tolerance and arrest characteristics of pressurized graphite/epoxy tape cylinders

An investigation of the damage tolerance and damage arrest characteristics of internally-pressurized graphite/epoxy tape cylinders with axial notches was conducted. An existing failure prediction methodology, developed and verified for quasi-isotropic graphite/epoxy fabric cylinders, was investigated for applicability to general tape layups. In addition, the effect of external circumferential stiffening bands on the direction of fracture path propagation and possible damage arrest was examined. Quasi-isotropic (90/0/plus or minus 45)s and structurally anisotropic (plus or minus 45/0)s and (plus or minus 45/90)s coupons and cylinders were constructed from AS4/3501-6 graphite/epoxy tape. Notched and unnotched coupons were tested in tension and the data correlated using the equation of Mar and Lin. Cylinders with through-thickness axial slits were pressurized to failure achieving a far-field two-to-one biaxial stress state. Experimental failure pressures of the (90/0/plus or minus 45)s cylinders agreed with predicted values for all cases but the specimen with the smallest slit. However, the failure pressures of the structurally anisotropic cylinders, (plus or minus 45/0)s and (plus or minus 45/90)s, were above the values predicted utilizing the predictive methodology in all cases. Possible factors neglected by the predictive methodology include structural coupling in the laminates and axial loading of the cylindrical specimens. Furthermore, applicability of the predictive methodology depends on the similarity of initial fracture modes in the coupon specimens and the cylinder specimens of the same laminate type. The existence of splitting which may be exacerbated by the axial loading in the cylinders, shows that this condition is not always met. The circumferential stiffeners were generally able to redirect fracture propagation from longitudinal to circumferential. A quantitative assessment for stiffener effectiveness in containing the fracture, based on cylinder radius, slit size, and bending stiffnesses of the laminates, is proposed

Damage tolerance and arrest characteristics of pressurized graphite/epoxy tape cylinders

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 1991.Includes bibliographical references (leaves 184-187).by Claudia Ute Ranniger.M.S

Collaborative System Design of Mixed Reality Communication for Medical Training

We present the design of a mixed reality (MR) telehealth training system that aims to close the gap between in-person and distance training and re-training for medical procedures. Our system uses real-time volumetric capture as a means for communicating and relating spatial information between the non-colocated trainee and instructor. The system's design is based on a requirements elicitation study performed in situ, at a medical school simulation training center. The focus is on the lightweight real-time transmission of volumetric data - meaning the use of consumer hardware, easy and quick deployment, and low-demand computations. We evaluate the MR system design by analyzing the workload for the users during medical training. We compare in-person, video, and MR training workloads. The results indicate that the overall workload for central line placement training with MR does not increase significantly compared to video communication. Our work shows that, when designed strategically together with domain experts, an MR communication system can be used effectively for complex medical procedural training without increasing the overall workload for users significantly. Moreover, MR systems offer new opportunities for teaching due to spatial information, hand tracking, and augmented communication

Measurement of CSF opening pressure during lumbar puncture in the sitting position in the Emergency Department

Background: Traditionally lumbar puncture (LP) is performed in the lateral decubitus position. For mechanical reasons, practicingphysicians may elect to perform the procedure with the patient in a sitting position. There are no data describing the normal range of cerebrospinal fluid (CSF) opening pressures (OP) inpatients in the sitting position. Objectives: We sought to identify a range of normal CSF OP in the sitting-up, feet supported position (SUFS), and to determine whether head height above the needle affects the variance of the obtained pressures. Methods: IRB-approved, prospective study of patients undergoing LP in two urban emergency departments (EDs). Exclusion criteria were \u3c 18 years old, positive CSF findings, contraindication to LP, known hydrocephalus, structural intracranial abnormality, or ventricular shunt. Physicians performed LP in either the lateral decubitus (LD) or SUFS position, as per clinical judgment. CSF OP was measured in all patients. In SUFS patient, head height above needle hub (measured vertically to the level of the external auditory meatus) was obtained. Results: Forty-two patients were included in the study (20 SUFS and 22 LD). There was no difference in age, height, or discharge rate in either group. There were more women in the LD groups (63% vs. 50%). The average OP was 14.8 cm higher in the SUFS position (19.8 cm LD vs 34.6 cm SUFS; p (SD) of OP pressures were similar (5.7 LD vs 5.9 SUFS) in the two groups. Average head height (HH) above the needle hub (SUFS only) was 28.5 cm (SD 7.9), and no correlation between HH and OP was found (R^2 = 0.06) Conclusion: In the general ED population, opening pressure on patients in the SUFS position is significantly higher than opening pressure in the LD position, with a similar distribution. Variations in opening pressure cannot be explained by variations in HH above the needle hub. An alternative measure to determine the effects of the CSF column height on SUFS pressures should be sought

A-PEX: A Case-Based Integrated Physical Diagnosis/Anatomy Program for First Year Medical Students

© 2011, Springer International Publishing. To better prepare first year students to apply physical examination in clinical clerkships we created A-PEX, a case-based program integrated into both their physical diagnosis and anatomy courses. In these two different but mutually reinforcing contexts students applied physical examination to differential diagnosis and simulated procedures to solve clinical problems

Conscious Sedation Simulation Course for Medical Providers and Its Effect on Decreasing Procedural Sedation-Related Complications in the ED

This study aims to improve training and decrease complications related to conscious sedation (light anesthesia to decrease pain during painful procedures). Conscious sedation is an integral part of an Emergency Medicine physician’s scope of practice, and residents are required to have performed a minimum of 15 conscious sedation procedures prior to graduation. At GW, resident training has typically included lectures/didactics, an occasional simulated case during the routine simulation training days, and hands on training/supervision in the ED. However, no dedicated conscious sedation curriculum exists, and the experience of residents in the program is variable. The investigators plan to develop a 4 hour integrated didactic and simulation curriculum for conscious sedation, and evaluate the effectiveness of the curriculum on resident knowledge, self-efficacy, and assess for impact on clinical outcomes (if any). The educational component will be conducted during a regularly scheduled grand rounds as a part of the residency curriculum. Residents will be provided with session pre-reading, complete a demographic survey and knowledge pretest, participate in the simulation training session, and then take a written post-test. A conscious sedation skills station will be included in the annual resident mock oral boards session to assess post course skill retention. Participants will be asked to provide anonymous feedback regarding the efficacy of the training. In addition, the investigators seek to extract clinical (Emergency Dept) conscious sedation data by reviewing charts from six month timeframes before and after the course is taught, to determine if there is an impact on clinical performance. Although a measurable change in complication rates is unlikely, smaller variations (such as duration of monitoring, degree of oxygen desaturation) may provide insight into whether the course has changed clinical practice. This course will ideally become a fixed part of the residency education curriculum, and later could be applied to any medical provider from any specialty (CME course) with tailored cases related to their practice

Exposure to a Virtual Reality Mass-Casualty Simulation Elicits a Differential Sympathetic Response in Medical Trainees and Attending Physicians

BACKGROUND: Previous studies have demonstrated the use of virtual reality (VR) in mass-casualty incident (MCI) simulation; however, it is uncertain if VR simulations can be a substitute for in-person disaster training. Demonstrating that VR MCI scenarios can elicit the same desired stress response achieved in live-action exercises is a first step in showing non-inferiority. The primary objective of this study was to measure changes in sympathetic nervous system (SNS) response via a decrease in heart rate variability (HRV) in subjects participating in a VR MCI scenario. METHODS: An MCI simulation was filmed with a 360º camera and shown to participants on a VR headset while simultaneously recording electrocardiography (EKG) and HRV activity. Baseline HRV was measured during a calm VR scenario immediately prior to exposure to the MCI scenarios, and SNS activation was captured as a decrease in HRV compared to baseline. Cognitive stress was measured using a validated questionnaire. Wilcoxon matched pairs signed rank analysis, Welch\u27s t-test, and multivariate logistic regression were performed with statistical significance established at P \u3c.05. RESULTS: Thirty-five subjects were enrolled: eight attending physicians (two surgeons, six Emergency Medicine [EM] specialists); 13 residents (five Surgery, eight EM); and 14 medical students (six pre-clinical, eight clinical-year students). Sympathetic nervous system activation was observed in all groups during the MCI compared to baseline (P \u3c.0001) and occurred independent of age, sex, years of experience, or prior MCI response experience. Overall, 23/35 subjects (65.7%) reported increased cognitive stress in the MCI (11/14 medical students, 9/13 residents, and 3/8 attendings). Resident and attending physicians had higher odds of discordance between SNS activation and cognitive stress compared to medical students (OR = 8.297; 95% CI, 1.408-64.60; P = .030). CONCLUSIONS: Live-actor VR MCI simulation elicited a strong sympathetic response across all groups. Thus, VR MCI training has the potential to guide acquisition of confidence in disaster response

Effects of designated leadership and team-size on cardiopulmonary resuscitation: The Basel-Washington SIMulation (BaWaSim) trial.

© 2018 Elsevier Inc. Objective: During cardiopulmonary resuscitation (CPR), it remains unclear whether designating an individual person as team leader compared with emergent leadership results in better team performance. Also, the effect of CPR team size on team performance remains understudied. Methods: This randomized-controlled trial compared designated versus emergent leadership and size of rescue team (3 vs 6 rescuers) on resuscitation performance. Results: We included 90 teams with a total of 408 students. No difference in mean (±SD) hands-on time (seconds) were observed between emergent leadership (106 ± 30) compared to designated leadership (103 ± 27) groups (adjusted difference − 2.97 (95%CI -15.75 to 9.80, p = 0.645), or between smaller (103 ± 30) and larger teams (106 ± 26, adjusted difference 3.53, 95%CI -8.47 to 15.53, p = 0.56). Emergent leadership groups had a shorter time to circulation check and first defibrillation, but the quality of CPR based on arm and shoulder position was lower. No differences in CPR quality measures were observed between smaller and larger teams. Conclusions: Within this international US/Swiss trial, leadership designation and larger team size did not improve hands-on time, but emergent leadership teams initiated defibrillation earlier. Improvements in performance may be more likely to be achieved by optimization of emergent leadership than increasing the size of cardiac arrest teams

Effects of designated leadership and team-size on cardiopulmonary resuscitation: The Basel-Washington SIMulation (BaWaSim) trial

© 2018 Elsevier Inc. Objective: During cardiopulmonary resuscitation (CPR), it remains unclear whether designating an individual person as team leader compared with emergent leadership results in better team performance. Also, the effect of CPR team size on team performance remains understudied. Methods: This randomized-controlled trial compared designated versus emergent leadership and size of rescue team (3 vs 6 rescuers) on resuscitation performance. Results: We included 90 teams with a total of 408 students. No difference in mean (±SD) hands-on time (seconds) were observed between emergent leadership (106 ± 30) compared to designated leadership (103 ± 27) groups (adjusted difference − 2.97 (95%CI -15.75 to 9.80, p = 0.645), or between smaller (103 ± 30) and larger teams (106 ± 26, adjusted difference 3.53, 95%CI -8.47 to 15.53, p = 0.56). Emergent leadership groups had a shorter time to circulation check and first defibrillation, but the quality of CPR based on arm and shoulder position was lower. No differences in CPR quality measures were observed between smaller and larger teams. Conclusions: Within this international US/Swiss trial, leadership designation and larger team size did not improve hands-on time, but emergent leadership teams initiated defibrillation earlier. Improvements in performance may be more likely to be achieved by optimization of emergent leadership than increasing the size of cardiac arrest teams