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Sample records for surgical learning curve

  1. Measuring the surgical 'learning curve': methods, variables and competency.

    Science.gov (United States)

    Khan, Nuzhath; Abboudi, Hamid; Khan, Mohammed Shamim; Dasgupta, Prokar; Ahmed, Kamran

    2014-03-01

    To describe how learning curves are measured and what procedural variables are used to establish a 'learning curve' (LC). To assess whether LCs are a valuable measure of competency. A review of the surgical literature pertaining to LCs was conducted using the Medline and OVID databases. Variables should be fully defined and when possible, patient-specific variables should be used. Trainee's prior experience and level of supervision should be quantified; the case mix and complexity should ideally be constant. Logistic regression may be used to control for confounding variables. Ideally, a learning plateau should reach a predefined/expert-derived competency level, which should be fully defined. When the group splitting method is used, smaller cohorts should be used in order to narrow the range of the LC. Simulation technology and competence-based objective assessments may be used in training and assessment in LC studies. Measuring the surgical LC has potential benefits for patient safety and surgical education. However, standardisation in the methods and variables used to measure LCs is required. Confounding variables, such as participant's prior experience, case mix, difficulty of procedures and level of supervision, should be controlled. Competency and expert performance should be fully defined. © 2013 The Authors. BJU International © 2013 BJU International.

  2. Learning Curve Analysis and Surgical Outcomes of Single-port Laparoscopic Myomectomy.

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    Lee, Hee Jun; Kim, Ju Yeong; Kim, Seul Ki; Lee, Jung Ryeol; Suh, Chang Suk; Kim, Seok Hyun

    2015-01-01

    To identify learning curves for single-port laparoscopic myomectomy (SPLM) and evaluate surgical outcomes according to the sequence of operation. A retrospective study. A university-based hospital (Canadian Task Force classification II-2). The medical records from 205 patients who had undergone SPLM from October 2009 to May 2013 were reviewed. Because the myomectomy time was significantly affected by the size and number of myomas removed by SPLM, cases in which 2 or more of the myomas removed were >7 cm in diameter were excluded. Furthermore, cases involving additional operations performed simultaneously (e.g., ovarian or hysteroscopic surgery) were also excluded. A total of 161 cases of SPLM were included. None. We assessed the SPLM learning curve via a graph based on operation time versus sequence of cases. Patients were chronologically arranged according to their surgery dates and were then placed into 1 of 4 groups according to their operation sequence. SPLM was completed successfully in 160 of 161 cases (99.4%). One case was converted to multiport surgery. Basal characteristics of the patients between the 4 groups did not differ. The median operation times for the 4 groups were 112.0, 92.8, 83.7, and 90.0 minutes, respectively. Operation time decreased significantly in the second, third, and fourth groups compared with that in the first group (p learning curve became less steep, was evident after about 45 operations. Results from the current study suggested that proficiency for SPLM was achieved after about 45 operations. Additionally, operation time decreased with experience without an increase in complication rate. Copyright © 2015 AAGL. Published by Elsevier Inc. All rights reserved.

  3. [Surgical learning curve for creation of vascular accesses for haemodialysis: value of medico-radio-surgical collaboration].

    Science.gov (United States)

    Van Glabeke, Emmanuel; Belenfant, Xavier; Barrou, Benoît; Adhemar, Jean-Pierre; Laedrich, Joëlle; Mavel, Marie-Christine; Challier, Emmanuel

    2005-04-01

    Creation of a vascular access (VA) for haemodialysis is a surgical procedure which comprises a failure rate related to the quality of the vessels and the operator's experience. The authors report the first 2 years of a young urologist's experience with this procedure in a local hospital in collaboration with the nephrology team. Patients undergoing creation of VA were divided into 2 chronological groups. The patient's age and gender, the cause of renal failure, the presence of diabetes, clinical examination of the upper limb, preoperative assessment of upper limb vessels, the type of anaesthesia, the operating time and the start of dialysis after the operation, as well as the functional results of the VA at 6 months were studied. Results concerning the patients of the first period were discussed by the operator and the nephrology team. During the first 9 months, 28 patients were operated, corresponding to 36 operations including 32 direct fistulas. Over the following 15 months, 61 patients were operated, with the creation of 63 VAs, including 55 direct fistulas. The failure rate (thrombosis or non-functioning VA) decreased from 32.1% to 11.1% (p=0.07), while the 2 groups were globally comparable. Evaluation of a new surgical procedure shows a number of failures, as for all learning curves. However, it helps to improve the results. Collaboration with nephrologists must comprise a discussion allowing the acceptance of certain failures, as they reflect compliance with a strategy of preservation of the vascular capital and a rational attempt to avoid a non-essential proximal access or bypass graft. The support of a motivated radiology team (preoperative assessment and management of complications) and the assistance of a more experienced operator are essential.

  4. Can a teaching assistant experience in a surgical anatomy course influence the learning curve for nontechnical skill development for surgical residents?

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    Heidenreich, Mark J; Musonza, Tashinga; Pawlina, Wojciech; Lachman, Nirusha

    2016-01-01

    The foundation upon which surgical residents are trained to work comprises more than just critical cognitive, clinical, and technical skill. In an environment where the synchronous application of expertise is vital to patient outcomes, the expectation for optimal functioning within a multidisciplinary team is extremely high. Studies have shown that for most residents, one of the most difficult milestones in the path to achieving professional expertise in a surgical career is overcoming the learning curve. This view point commentary provides a reflection from the two senior medical students who have participated in the Student-as-Teacher program developed by the Department of Anatomy at Mayo Clinic, designed to prepare students for their teaching assistant (TA) role in anatomy courses. Both students participated as TAs in a six week surgical anatomy course for surgical first assistant students offered by the School of Health Sciences at Mayo Clinic. Development of teaching skills, nontechnical leadership, communication, and assessment skills, are discussed in relation to their benefits in preparing senior medical students for surgical residency. © 2015 American Association of Anatomists.

  5. Learning Curve? Which One?

    Directory of Open Access Journals (Sweden)

    Paulo Prochno

    2004-07-01

    Full Text Available Learning curves have been studied for a long time. These studies provided strong support to the hypothesis that, as organizations produce more of a product, unit costs of production decrease at a decreasing rate (see Argote, 1999 for a comprehensive review of learning curve studies. But the organizational mechanisms that lead to these results are still underexplored. We know some drivers of learning curves (ADLER; CLARK, 1991; LAPRE et al., 2000, but we still lack a more detailed view of the organizational processes behind those curves. Through an ethnographic study, I bring a comprehensive account of the first year of operations of a new automotive plant, describing what was taking place on in the assembly area during the most relevant shifts of the learning curve. The emphasis is then on how learning occurs in that setting. My analysis suggests that the overall learning curve is in fact the result of an integration process that puts together several individual ongoing learning curves in different areas throughout the organization. In the end, I propose a model to understand the evolution of these learning processes and their supporting organizational mechanisms.

  6. Mentorship, learning curves, and balance.

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    Cohen, Meryl S; Jacobs, Jeffrey P; Quintessenza, James A; Chai, Paul J; Lindberg, Harald L; Dickey, Jamie; Ungerleider, Ross M

    2007-09-01

    meet this challenge without a painful learning curve belongs to both the younger professionals, who must progress through the learning curve, and the more mature professionals who must create an appropriate environment for learning. In addition to mentorship, the detailed tracking of outcomes is an essential tool for mastering any learning curve. It is crucial to utilize a detailed database to track outcomes, to learn, and to protect both yourself and your patients. It is our professional responsibility to engage in self-evaluation, in part employing voluntary sharing of data. For cardiac surgical subspecialties, the databases now existing for The European Association for CardioThoracic Surgery and The Society of Thoracic Surgeons represent the ideal tool for monitoring outcomes. Evolving initiatives in the fields of paediatric cardiology, paediatric critical care, and paediatric cardiac anaesthesia will play similar roles.A variety of professional and personal challenges must be met by all those working in health care. The acquisition of learned skills, and the use of special tools, will facilitate the process of conquering these challenges. Choosing appropriate role models and mentors can help progression through any learning curve in a controlled and protected fashion. Professional and personal satisfaction are both necessities. Finding the satisfactory balance between work and home life is difficult, but possible with the right tools, organization skills, and support system at work and at home. The concepts of mentorship, learning curves and balance cannot be underappreciated.

  7. Effects of Pathologic Stage on the Learning Curve for Radical Prostatectomy: Evidence That Recurrence in Organ-Confined Cancer Is Largely Related to Inadequate Surgical Technique

    Science.gov (United States)

    Vickers, Andrew J.; Bianco, Fernando J.; Gonen, Mithat; Cronin, Angel M.; Eastham, James A.; Schrag, Deborah; Klein, Eric A.; Reuther, Alwyn M.; Kattan, Michael W.; Pontes, J. Edson; Scardino, Peter T.

    2008-01-01

    Objectives We previously demonstrated that there is a learning curve for open radical prostatectomy. We sought to determine whether the effects of the learning curve are modified by pathologic stage. Methods The study included 7765 eligible prostate cancer patients treated with open radical prostatectomy by one of 72 surgeons. Surgeon experience was coded as the total number of radical prostatectomies conducted by the surgeon prior to a patient’s surgery. Multivariable regression models of survival time were used to evaluate the association between surgeon experience and biochemical recurrence, with adjustment for PSA, stage, and grade. Analyses were conducted separately for patients with organ-confined and locally advanced disease. Results Five-year recurrence-free probability for patients with organ-confined disease approached 100% for the most experienced surgeons. Conversely, the learning curve for patients with locally advanced disease reached a plateau at approximately 70%, suggesting that about a third of these patients cannot be cured by surgery alone. Conclusions Excellent rates of cancer control for patients with organ-confined disease treated by the most experienced surgeons suggest that the primary reason such patients recur is inadequate surgical technique. PMID:18207316

  8. Endoscopic endonasal pituitary adenomas surgery: the surgical experience of 178 consecutive patients and learning curve of two neurosurgeons.

    Science.gov (United States)

    Shou, Xuefei; Shen, Ming; Zhang, Qilin; Zhang, Yichao; He, Wenqiang; Ma, Zengyi; Zhao, Yao; Li, Shiqi; Wang, Yongfei

    2016-11-30

    We aim to study surgical technique and analyze the related factors affecting tumor total removal and postoperative endocrinological remission for endoscopic endonasal pituitary adenomas surgery. We retrospectively analyzed 178 endoscopic endonasal pituitary adenomas surgery from March 2011 to May 2014. Endonasal approach included the routine transnasal-sphenoidal approach, transnasal- maxillary sinus approach in four cases and transnasal-clivus approach in one case. According to postoperative imaging data and endocrine examination results, total removal was achieved in 129 patients (72.5%), and endocrinological remission was achieved in 38 patients with functional adenomas (44.1%). Statistical analysis of the clinical data showed that total removal rate was much closely related to tumor volume (P = 0.006), and tumor invasiveness (P < 0.001). In this study, we found tumor sizes and invasion of cavernous sinus were related to total removal rate and endocrinological remission rate; the direction and degree of tumor invasion, and the surgeon's experience were the key influence factors of the endocrinological remission rate for invasive functional pituitary adenomas.

  9. Management of the learning curve

    DEFF Research Database (Denmark)

    Pedersen, Peter-Christian; Slepniov, Dmitrij

    2016-01-01

    Purpose – This paper focuses on the management of the learning curve in overseas capacity expansions. The purpose of this paper is to unravel the direct as well as indirect influences on the learning curve and to advance the understanding of how these affect its management. Design...... the dimensions of the learning process involved in a capacity expansion project and identified the direct and indirect labour influences on the production learning curve. On this basis, the study proposes solutions to managing learning curves in overseas capacity expansions. Furthermore, the paper concludes...... with measures that have the potential to significantly reduce the non-value-added time when establishing new capacities overseas. Originality/value – The paper uses a longitudinal in-depth case study of a Danish wind turbine manufacturer and goes beyond a simplistic treatment of the lead time and learning...

  10. Perioperative surgical complications and learning curve associated with minimally invasive transforaminal lumbar interbody fusion: a single-institute experience.

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    Park, Yung; Lee, Soo Bin; Seok, Sang Ok; Jo, Byung Woo; Ha, Joong Won

    2015-03-01

    As surgical complications tend to occur more frequently in the beginning stages of a surgeon's career, knowledge of perioperative complications is important to perform a safe procedure, especially if the surgeon is a novice. We sought to identify and describe perioperative complications and their management in connection with minimally invasive transforaminal lumbar interbody fusion (TLIF). We performed a retrospective chart review of our first 124 patients who underwent minimally invasive TLIF. The primary outcome measure was adverse events during the perioperative period, including neurovascular injury, implant-related complications, and wound infection. Pseudarthroses and adjacent segment pathologies were not included in this review. Adverse events that were not specifically related to spinal surgery and did not affect recovery were also excluded. Perioperative complications occurred in 9% of patients (11/124); including three cases of temporary postoperative neuralgia, two deep wound infections, two pedicle screw misplacements, two cage migrations, one dural tear, and one grafted bone extrusion. No neurologic deficits were reported. Eight complications occurred in the first one-third of the series and only 3 complications occurred in the last two-thirds of the series. Additional surgeries were performed in 6% of patients (7/124); including four reoperations (two for cage migrations, one for a misplaced screw, and one for an extruded graft bone fragment) and three hardware removals (one for a misplaced screw and two for infected cages). We found perioperative complications occurred more often in the early period of a surgeon's experience with minimally invasive TLIF. Implant-related complications were common and successfully managed by additional surgeries in this series. We suggest greater caution should be exercised to avoid the potential complications, especially when surgeon is a novice to this procedure.

  11. Learning from uncertain curves

    DEFF Research Database (Denmark)

    Mallasto, Anton; Feragen, Aasa

    2017-01-01

    We introduce a novel framework for statistical analysis of populations of nondegenerate Gaussian processes (GPs), which are natural representations of uncertain curves. This allows inherent variation or uncertainty in function-valued data to be properly incorporated in the population analysis. Us...

  12. Learning curve for radical retropubic prostatectomy

    Directory of Open Access Journals (Sweden)

    Fernando J. A. Saito

    2011-02-01

    Full Text Available PURPOSE: The learning curve is a period in which the surgical procedure is performed with difficulty and slowness, leading to a higher risk of complications and reduced effectiveness due the surgeon's inexperience. We sought to analyze the residents' learning curve for open radical prostatectomy (RP in a training program. MATERIALS AND METHODS: We conducted a prospective study from June 2006 to January 2008 in the academic environment of the University of São Paulo. Five residents operated on 184 patients during a four-month rotation in the urologic oncology division, mentored by the same physician assistants. We performed sequential analyses according to the number of surgeries, as follows: = 10, 11 to 19, 20 to 28, and = 29. RESULTS: The residents performed an average of 37 RP each. The average psa was 9.3 ng/mL and clinical stage T1c in 71% of the patients. The pathological stage was pT2 (73%, pT3 (23%, pT4 (4%, and 46% of the patients had a Gleason score 7 or higher. In all surgeries, the average operative time and estimated blood loss was 140 minutes and 488 mL. Overall, 7.2% of patients required blood transfusion, and 23% had positive surgical margins. CONCLUSION: During the initial RP learning curve, we found a significant reduction in the operative time; blood transfusion during the procedures and positive surgical margin rate were stable in our series.

  13. Analysis of the learning curve for transurethral resection of the prostate. Is there any influence of musical instrument and video game skills on surgical performance?

    Science.gov (United States)

    Yamaçake, Kleiton Gabriel Ribeiro; Nakano, Elcio Tadashi; Soares, Iva Barbosa; Cordeiro, Paulo; Srougi, Miguel; Antunes, Alberto Azoubel

    2015-09-01

    To evaluate the learning curve for transurethral resection of the prostate (TURP) among urology residents and study the impact of video game and musical instrument playing abilities on its performance. A prospective study was performed from July 2009 to January 2013 with patients submitted to TURP for benign prostatic hyperplasia. Fourteen residents operated on 324 patients. The following parameters were analyzed: age, prostate-specific antigen levels, prostate weight on ultrasound, pre- and postoperative serum sodium and hemoglobin levels, weight of resected tissue, operation time, speed of resection, and incidence of capsular lesions. Gender, handedness, and prior musical instrument and video game playing experience were recorded using survey responses. The mean resection speed in the first 10 procedures was 0.36 g/min and reached a mean of 0.51 g/min after the 20(th) procedure. The incidence of capsular lesions decreased progressively. The operation time decreased progressively for each subgroup regardless of the difference in the weight of tissue resected. Those experienced in playing video games presented superior resection speed (0.45 g/min) when compared with the novice (0.35 g/min) and intermediate (0.38 g/min) groups (p=0.112). Musical instrument playing abilities did not affect the surgical performance. Speed of resection, weight of resected tissue, and percentage of resected tissue improve significantly and the incidence of capsular lesions reduces after the performance of 10 TURP procedures. Experience in playing video games or musical instruments does not have a significant effect on outcomes.

  14. Microvascular Anastomosis: Proposition of a Learning Curve.

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    Mokhtari, Pooneh; Tayebi Meybodi, Ali; Benet, Arnau; Lawton, Michael T

    2018-04-14

    Learning to perform a microvascular anastomosis is one of the most difficult tasks in cerebrovascular surgery. Previous studies offer little regarding the optimal protocols to maximize learning efficiency. This failure stems mainly from lack of knowledge about the learning curve of this task. To delineate this learning curve and provide information about its various features including acquisition, improvement, consistency, stability, and recall. Five neurosurgeons with an average surgical experience history of 5 yr and without any experience in bypass surgery performed microscopic anastomosis on progressively smaller-caliber silastic tubes (Biomet, Palm Beach Gardens, Florida) during 24 consecutive sessions. After a 1-, 2-, and 8-wk retention interval, they performed recall test on 0.7-mm silastic tubes. The anastomoses were rated based on anastomosis patency and presence of any leaks. Improvement rate was faster during initial sessions compared to the final practice sessions. Performance decline was observed in the first session of working on a smaller-caliber tube. However, this rapidly improved during the following sessions of practice. Temporary plateaus were seen in certain segments of the curve. The retention interval between the acquisition and recall phase did not cause a regression to the prepractice performance level. Learning the fine motor task of microvascular anastomosis adapts to the basic rules of learning such as the "power law of practice." Our results also support the improvement of performance during consecutive sessions of practice. The objective evidence provided may help in developing optimized learning protocols for microvascular anastomosis.

  15. Learning Curves of Virtual Mastoidectomy in Distributed and Massed Practice

    DEFF Research Database (Denmark)

    Andersen, Steven Arild Wuyts; Konge, Lars; Cayé-Thomasen, Per

    2015-01-01

    IMPORTANCE: Repeated and deliberate practice is crucial in surgical skills training, and virtual reality (VR) simulation can provide self-directed training of basic surgical skills to meet the individual needs of the trainee. Assessment of the learning curves of surgical procedures is pivotal...... in understanding skills acquisition and best-practice implementation and organization of training. OBJECTIVE: To explore the learning curves of VR simulation training of mastoidectomy and the effects of different practice sequences with the aim of proposing the optimal organization of training. DESIGN, SETTING...... plateaued on a score of 16.0 (15.3-16.7) at approximately the ninth repetition, but the individual learning curves were highly variable. CONCLUSIONS AND RELEVANCE: Novices can acquire basic mastoidectomy competencies with self-directed VR simulation training. Training should be organized with distributed...

  16. Robotic Mitral Valve Repair: The Learning Curve.

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    Goodman, Avi; Koprivanac, Marijan; Kelava, Marta; Mick, Stephanie L; Gillinov, A Marc; Rajeswaran, Jeevanantham; Brzezinski, Anna; Blackstone, Eugene H; Mihaljevic, Tomislav

    Adoption of robotic mitral valve surgery has been slow, likely in part because of its perceived technical complexity and a poorly understood learning curve. We sought to correlate changes in technical performance and outcome with surgeon experience in the "learning curve" part of our series. From 2006 to 2011, two surgeons undertook robotically assisted mitral valve repair in 458 patients (intent-to-treat); 404 procedures were completed entirely robotically (as-treated). Learning curves were constructed by modeling surgical sequence number semiparametrically with flexible penalized spline smoothing best-fit curves. Operative efficiency, reflecting technical performance, improved for (1) operating room time for case 1 to cases 200 (early experience) and 400 (later experience), from 414 to 364 to 321 minutes (12% and 22% decrease, respectively), (2) cardiopulmonary bypass time, from 148 to 102 to 91 minutes (31% and 39% decrease), and (3) myocardial ischemic time, from 119 to 75 to 68 minutes (37% and 43% decrease). Composite postoperative complications, reflecting safety, decreased from 17% to 6% to 2% (63% and 85% decrease). Intensive care unit stay decreased from 32 to 28 to 24 hours (13% and 25% decrease). Postoperative stay fell from 5.2 to 4.5 to 3.8 days (13% and 27% decrease). There were no in-hospital deaths. Predischarge mitral regurgitation of less than 2+, reflecting effectiveness, was achieved in 395 (97.8%), without correlation to experience; return-to-work times did not change substantially with experience. Technical efficiency of robotic mitral valve repair improves with experience and permits its safe and effective conduct.

  17. Distribution of isodose curves in urological surgical procedures

    International Nuclear Information System (INIS)

    Lanfredi, M.P.; Dias, J.H.; Ravazio, R.C.; Anés, M.; Bacelar, A.; Lykawka, R.

    2017-01-01

    During urological surgical procedures with fluoroscopy, the doses of the care team may be significant. However, the knowledge of the occupational exposure of these professionals is still very incipient in the national surgical centers. The objective of the study is to determine the isodose curves of the urological surgical procedures, in order to estimate the exposure of the personnel involved. The equipment used was a Arco-C BV Philips Bracelet. Patients with thicknesses of 20 and 28 cm were simulated using acrylic plates. The dose rates were measured with RaySafe i2 Unfors dosimeters positioned in a 50 x 50 cm mesh at three different heights of the floor: 95, 125 and 165 centimeters respectively corresponding to the gonadal, thoracic and crystalline regions of a typical adult . The isodose curves applied to the distribution of the surgical team suggest that the exposures are in the following descending order of intensity: primary physician, auxiliary physician, scrub nurse, anesthetist and nurse

  18. Learning curves in energy planning models

    Energy Technology Data Exchange (ETDEWEB)

    Barreto, L; Kypreos, S [Paul Scherrer Inst. (PSI), Villigen (Switzerland)

    1999-08-01

    This study describes the endogenous representation of investment cost learning curves into the MARKAL energy planning model. A piece-wise representation of the learning curves is implemented using Mixed Integer Programming. The approach is briefly described and some results are presented. (author) 3 figs., 5 refs.

  19. Learning curves in health professions education.

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    Pusic, Martin V; Boutis, Kathy; Hatala, Rose; Cook, David A

    2015-08-01

    Learning curves, which graphically show the relationship between learning effort and achievement, are common in published education research but are not often used in day-to-day educational activities. The purpose of this article is to describe the generation and analysis of learning curves and their applicability to health professions education. The authors argue that the time is right for a closer look at using learning curves-given their desirable properties-to inform both self-directed instruction by individuals and education management by instructors.A typical learning curve is made up of a measure of learning (y-axis), a measure of effort (x-axis), and a mathematical linking function. At the individual level, learning curves make manifest a single person's progress towards competence including his/her rate of learning, the inflection point where learning becomes more effortful, and the remaining distance to mastery attainment. At the group level, overlaid learning curves show the full variation of a group of learners' paths through a given learning domain. Specifically, they make overt the difference between time-based and competency-based approaches to instruction. Additionally, instructors can use learning curve information to more accurately target educational resources to those who most require them.The learning curve approach requires a fine-grained collection of data that will not be possible in all educational settings; however, the increased use of an assessment paradigm that explicitly includes effort and its link to individual achievement could result in increased learner engagement and more effective instructional design.

  20. Investigation of learning and experience curves

    Energy Technology Data Exchange (ETDEWEB)

    Krawiec, F.; Thornton, J.; Edesess, M.

    1980-04-01

    The applicability of learning and experience curves for predicting future costs of solar technologies is assessed, and the major test case is the production economics of heliostats. Alternative methods for estimating cost reductions in systems manufacture are discussed, and procedures for using learning and experience curves to predict costs are outlined. Because adequate production data often do not exist, production histories of analogous products/processes are analyzed and learning and aggregated cost curves for these surrogates estimated. If the surrogate learning curves apply, they can be used to estimate solar technology costs. The steps involved in generating these cost estimates are given. Second-generation glass-steel and inflated-bubble heliostat design concepts, developed by MDAC and GE, respectively, are described; a costing scenario for 25,000 units/yr is detailed; surrogates for cost analysis are chosen; learning and aggregate cost curves are estimated; and aggregate cost curves for the GE and MDAC designs are estimated. However, an approach that combines a neoclassical production function with a learning-by-doing hypothesis is needed to yield a cost relation compatible with the historical learning curve and the traditional cost function of economic theory.

  1. Learning Curves of Virtual Mastoidectomy in Distributed and Massed Practice.

    Science.gov (United States)

    Andersen, Steven Arild Wuyts; Konge, Lars; Cayé-Thomasen, Per; Sørensen, Mads Sølvsten

    2015-10-01

    Repeated and deliberate practice is crucial in surgical skills training, and virtual reality (VR) simulation can provide self-directed training of basic surgical skills to meet the individual needs of the trainee. Assessment of the learning curves of surgical procedures is pivotal in understanding skills acquisition and best-practice implementation and organization of training. To explore the learning curves of VR simulation training of mastoidectomy and the effects of different practice sequences with the aim of proposing the optimal organization of training. A prospective trial with a 2 × 2 design was conducted at an academic teaching hospital. Participants included 43 novice medical students. Of these, 21 students completed time-distributed practice from October 14 to November 29, 2013, and a separate group of 19 students completed massed practice on May 16, 17, or 18, 2014. Data analysis was performed from June 6, 2014, to March 3, 2015. Participants performed 12 repeated virtual mastoidectomies using a temporal bone surgical simulator in either a distributed (practice blocks spaced in time) or massed (all practice in 1 day) training program with randomization for simulator-integrated tutoring during the first 5 sessions. Performance was assessed using a modified Welling Scale for final product analysis by 2 blinded senior otologists. Compared with the 19 students in the massed practice group, the 21 students in the distributed practice group were older (mean age, 25.1 years), more often male (15 [62%]), and had slightly higher mean gaming frequency (2.3 on a 1-5 Likert scale). Learning curves were established and distributed practice was found to be superior to massed practice, reported as mean end score (95% CI) of 15.7 (14.4-17.0) in distributed practice vs. 13.0 (11.9-14.1) with massed practice (P = .002). Simulator-integrated tutoring accelerated the initial performance, with mean score for tutored sessions of 14.6 (13.9-15.2) vs. 13.4 (12.8-14.0) for

  2. The learning curve for hip arthroscopy: a systematic review.

    Science.gov (United States)

    Hoppe, Daniel J; de Sa, Darren; Simunovic, Nicole; Bhandari, Mohit; Safran, Marc R; Larson, Christopher M; Ayeni, Olufemi R

    2014-03-01

    The learning curve for hip arthroscopy is consistently characterized as "steep." The purpose of this systematic review was to (1) identify the various learning curves reported in the literature, (2) examine the evidence supporting these curves, and (3) determine whether this evidence supports an accepted number of cases needed to achieve proficiency. The electronic databases Embase and Medline were screened for any clinical studies reporting learning curves in hip arthroscopy. Two reviewers conducted a full-text review of eligible studies and a hand search of conference proceedings and reference sections of the included articles. Inclusion/exclusion criteria were applied, and a quality assessment was completed for each included article. Descriptive statistics were compiled. We identified 6 studies with a total of 1,063 patients. Studies grouped surgical cases into "early" versus "late" in a surgeon's experience, with 30 cases being the most common cutoff used. Most of these studies used descriptive statistics and operative time and complication rates as measures of competence. Five of 6 studies showed improvement in these measures between early and late experience, but only one study proposed a bona fide curve. This review shows that when 30 cases was used as the cutoff point to differentiate between early and late cases in a surgeon's experience, there were significant reductions in operative time and complication rates. However, there was insufficient evidence to quantify the learning curve and validate 30, or any number of cases, as the point at which the learning curve plateaus. As a result, this number should be interpreted with caution. Level IV, systematic review of Level IV studies. Copyright © 2014 Arthroscopy Association of North America. Published by Elsevier Inc. All rights reserved.

  3. Learning curve for laparoscopic Heller myotomy and Dor fundoplication for achalasia.

    Science.gov (United States)

    Yano, Fumiaki; Omura, Nobuo; Tsuboi, Kazuto; Hoshino, Masato; Yamamoto, Seryung; Akimoto, Shunsuke; Masuda, Takahiro; Kashiwagi, Hideyuki; Yanaga, Katsuhiko

    2017-01-01

    Although laparoscopic Heller myotomy and Dor fundoplication (LHD) is widely performed to address achalasia, little is known about the learning curve for this technique. We assessed the learning curve for performing LHD. Of the 514 cases with LHD performed between August 1994 and March 2016, the surgical outcomes of 463 cases were evaluated after excluding 50 cases with reduced port surgery and one case with the simultaneous performance of laparoscopic distal partial gastrectomy. A receiver operating characteristic (ROC) curve analysis was used to identify the cut-off value for the number of surgical experiences necessary to become proficient with LHD, which was defined as the completion of the learning curve. We defined the completion of the learning curve when the following 3 conditions were satisfied. 1) The operation time was less than 165 minutes. 2) There was no blood loss. 3) There was no intraoperative complication. In order to establish the appropriate number of surgical experiences required to complete the learning curve, the cut-off value was evaluated by using a ROC curve (AUC 0.717, p < 0.001). Finally, we identified the cut-off value as 16 surgical cases (sensitivity 0.706, specificity 0.646). Learning curve seems to complete after performing 16 cases.

  4. Learning curve for laparoscopic Heller myotomy and Dor fundoplication for achalasia.

    Directory of Open Access Journals (Sweden)

    Fumiaki Yano

    Full Text Available Although laparoscopic Heller myotomy and Dor fundoplication (LHD is widely performed to address achalasia, little is known about the learning curve for this technique. We assessed the learning curve for performing LHD.Of the 514 cases with LHD performed between August 1994 and March 2016, the surgical outcomes of 463 cases were evaluated after excluding 50 cases with reduced port surgery and one case with the simultaneous performance of laparoscopic distal partial gastrectomy. A receiver operating characteristic (ROC curve analysis was used to identify the cut-off value for the number of surgical experiences necessary to become proficient with LHD, which was defined as the completion of the learning curve.We defined the completion of the learning curve when the following 3 conditions were satisfied. 1 The operation time was less than 165 minutes. 2 There was no blood loss. 3 There was no intraoperative complication. In order to establish the appropriate number of surgical experiences required to complete the learning curve, the cut-off value was evaluated by using a ROC curve (AUC 0.717, p < 0.001. Finally, we identified the cut-off value as 16 surgical cases (sensitivity 0.706, specificity 0.646.Learning curve seems to complete after performing 16 cases.

  5. Learning curves for mutual information maximization

    International Nuclear Information System (INIS)

    Urbanczik, R.

    2003-01-01

    An unsupervised learning procedure based on maximizing the mutual information between the outputs of two networks receiving different but statistically dependent inputs is analyzed [S. Becker and G. Hinton, Nature (London) 355, 161 (1992)]. For a generic data model, I show that in the large sample limit the structure in the data is recognized by mutual information maximization. For a more restricted model, where the networks are similar to perceptrons, I calculate the learning curves for zero-temperature Gibbs learning. These show that convergence can be rather slow, and a way of regularizing the procedure is considered

  6. From Curve Fitting to Machine Learning

    CERN Document Server

    Zielesny, Achim

    2011-01-01

    The analysis of experimental data is at heart of science from its beginnings. But it was the advent of digital computers that allowed the execution of highly non-linear and increasingly complex data analysis procedures - methods that were completely unfeasible before. Non-linear curve fitting, clustering and machine learning belong to these modern techniques which are a further step towards computational intelligence. The goal of this book is to provide an interactive and illustrative guide to these topics. It concentrates on the road from two dimensional curve fitting to multidimensional clus

  7. A learning curve for solar thermal power

    Science.gov (United States)

    Platzer, Werner J.; Dinter, Frank

    2016-05-01

    Photovoltaics started its success story by predicting the cost degression depending on cumulated installed capacity. This so-called learning curve was published and used for predictions for PV modules first, then predictions of system cost decrease also were developed. This approach is less sensitive to political decisions and changing market situations than predictions on the time axis. Cost degression due to innovation, use of scaling effects, improved project management, standardised procedures including the search for better sites and optimization of project size are learning effects which can only be utilised when projects are developed. Therefore a presentation of CAPEX versus cumulated installed capacity is proposed in order to show the possible future advancement of the technology to politics and market. However from a wide range of publications on cost for CSP it is difficult to derive a learning curve. A logical cost structure for direct and indirect capital expenditure is needed as the basis for further analysis. Using derived reference cost for typical power plant configurations predictions of future cost have been derived. Only on the basis of that cost structure and the learning curve levelised cost of electricity for solar thermal power plants should be calculated for individual projects with different capacity factors in various locations.

  8. Hydrogen technologies and the technology learning curve

    International Nuclear Information System (INIS)

    Rogner, H.-H.

    1998-01-01

    On their bumpy road to commercialization, hydrogen production, delivery and conversion technologies not only require dedicated research, development and demonstration efforts, but also protected niche markets and early adopters. While niche markets utilize the unique technological properties of hydrogen, adopters exhibit a willingness to pay a premium for hydrogen fueled energy services. The concept of the technology learning curve is applied to estimate the capital requirements associated with the commercialization process of several hydrogen technologies. (author)

  9. Learning curves for solid oxide fuel cells

    International Nuclear Information System (INIS)

    Rivera-Tinoco, Rodrigo; Schoots, Koen; Zwaan, Bob van der

    2012-01-01

    Highlights: ► We present learning curves for fuel cells based on empirical data. ► We disentangle different cost reduction mechanisms for SOFCs. ► We distinguish between learning-by-doing, R and D, economies-of-scale and automation. - Abstract: In this article we present learning curves for solid oxide fuel cells (SOFCs). With data from fuel cell manufacturers we derive a detailed breakdown of their production costs. We develop a bottom-up model that allows for determining overall SOFC manufacturing costs with their respective cost components, among which material, energy, labor and capital charges. The results obtained from our model prove to deviate by at most 13% from total cost figures quoted in the literature. For the R and D stage of development and diffusion, we find local learning rates between 13% and 17% and we demonstrate that the corresponding cost reductions result essentially from learning-by-searching effects. When considering periods in time that focus on the pilot and early commercial production stages, we find regional learning rates of 27% and 1%, respectively, which we assume derive mainly from genuine learning phenomena. These figures turnout significantly higher, approximately 44% and 12% respectively, if also effects of economies-of-scale and automation are included. When combining all production stages we obtain lr = 35%, which represents a mix of cost reduction phenomena. This high learning rate value and the potential to scale up production suggest that continued efforts in the development of SOFC manufacturing processes, as well as deployment and use of SOFCs, may lead to substantial further cost reductions.

  10. Prospects for PV: a learning curve analysis

    International Nuclear Information System (INIS)

    Zwaan, Bob van der; Rabi, A.

    2003-01-01

    This article gives an overview of the current state-of-the-art of photovoltaic electricity technology, and addresses its potential for cost reductions over the first few decades of the 21st century. Current PV production cost ranges are presented, both in terms of capacity installation and electricity generation, of single crystalline silicon, multi-crystalline silicon, amorphous silicon and other thin film technologies. Possible decreases of these costs are assessed, as expected according to the learning-curve methodology. We also estimate how much PV could gain if external costs (due to environmental and health damage) of energy were internalised, for example by an energy tax. Our conclusions are that, (1) mainly due its high costs, PV electricity is unlikely to play a major role in global energy supply and carbon emissions abatement before 2020, (2) extrapolating learning curves observed in the past, one can expect its costs to decrease significantly over the coming years, so that a considerable PV electricity share world-wide could materialise after 2020, (3) niche-market applications, e.g. using stand-alone systems in remote areas, are crucial for continuing 'the ride along the learning curve', (4) damage costs of conventional (fossil) power sources are considerable, and their internalisation would improve the competitiveness of PV, although probably not enough to close the current cost gap. (author)

  11. Endoscopic sleeve gastroplasty: the learning curve.

    Science.gov (United States)

    Hill, Christine; El Zein, Mohamad; Agnihotri, Abhishek; Dunlap, Margo; Chang, Angela; Agrawal, Alison; Barola, Sindhu; Ngamruengphong, Saowanee; Chen, Yen-I; Kalloo, Anthony N; Khashab, Mouen A; Kumbhari, Vivek

    2017-09-01

     Endoscopic sleeve gastroplasty (ESG) is gaining traction as a minimally invasive bariatric treatment. Concern that the learning curve may be slow, even among those proficient in endoscopic suturing, is a barrier to widespread implementation of the procedure. Therefore, we aimed to define the learning curve for ESG in a single endoscopist experienced in endoscopic suturing who participated in a 1-day ESG training program.  Consecutive patients who underwent ESG between February 2016 and November 2016 were included. The performing endoscopist, who is proficient in endoscopic suturing for non-ESG procedures, participated in a 1-day ESG training session before offering ESG to patients. The outcome measurements were length of procedure (LOP) and number of plications per procedure. Nonlinear regression was used to determine the learning plateau and calculate the learning rate.  Twenty-one consecutive patients (8 males), with mean age 47.7 ± 11.2 years and mean body mass index 41.8 ± 8.5 kg/m 2 underwent ESG. LOP decreased significantly across consecutive procedures, with a learning plateau at 101.5 minutes and a learning rate of 7 cases ( P  = 0.04). The number of plications per procedure also decreased significantly across consecutive procedures, with a plateau at 8 sutures and a learning rate of 9 cases ( P  < 0.001). Further, the average time per plication decreased significantly with consecutive procedures, reaching a plateau at 9 procedures ( P  < 0.001).  Endoscopists experienced in endoscopic suturing are expected to achieve a reduction in LOP and number of plications per procedure in successive cases, with progress plateauing at 7 and 9 cases, respectively.

  12. Learning curves for solid oxide fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Rivera-Tinoco, R.; Schoots, K. [Energy research Centre of the Netherlands (Netherlands). Policy Studies; Zwaan, B.C.C. van der [Energy research Centre of the Netherlands (Netherlands). Policy Studies; Columbia Univ., New York City, NY (United States). Lenfest Center for Sustainable Energy

    2010-07-01

    We present learning curves for solid oxide fuel cells (SOFCs) and combined heat and power (CHP) SOFC systems with an electric capacity between 1 and 250 kW. On the basis of the cost breakdown of production cost data from fuel cell manufacturers, we developed a bottom-up model that allows for determining overall manufacturing costs from their respective cost components, among which material, energy, labor, and capital charges. The results obtained from our model prove to deviate by at most 13% from total cost figures quoted in the literature. For the early pilot stage of development, we find for SOFC manufacturing a learning rate between 14% and 17%, and for total SOFC system fabrication between 16% and 19%. We argue that the corresponding cost reductions result largely from learning-by-searching effects (R and D) rather than learning-by-doing. When considering a longer time frame that includes the early commercial production stage, we find learning rates between 14% and 39%, which represent a mix of phenomena such as learning-by-doing, learning-by-searching, economies-of-scale and automation. (orig.)

  13. LEARNING CURVE IN ENDOSCOPIC TRANSNASAL SELLAR REGION SURGERY

    Directory of Open Access Journals (Sweden)

    Ananth G

    2016-07-01

    Full Text Available BACKGROUND The endoscopic endonasal approach for the sellar region lesions is a novel technique and an effective surgical option. The evidence thus far has been conflicting with reports in favour and against a learning curve. We attempt to determine the learning curve associated with this approach. METHODS Retrospective and prospective data of the patients who were surgically treated for sellar region lesions between the year 2013 and 2016 was collected, 32 patients were operated by the endoscopic endonasal approach at Vydehi Institute of Medical Sciences and Research Centre, Bangalore. Age, sex, presenting symptoms, length of hospital stay, surgical approach, type of dissection, duration of surgery, sellar floor repair, intraoperative and postoperative complications were noted. All the procedures were performed by a single neurosurgeon. RESULTS A total of 32 patients were operated amongst which 21 patients were non-functioning pituitary adenomas, 2 were growth hormone secreting functional adenomas, 1 was an invasive pituitary adenoma, 4 were craniopharyngiomas, 2 were meningiomas, 1 was Rathke’s cleft cyst and 1 was a clival chordoma. Headache was the mode of presentation in 12 patients, 12 patients had visual deficits, 6 patients presented with hormonal disturbances amongst which 4 patients presented with features of panhypopituitarism and 2 with acromegaly. Amongst the 4 patients with panhypopituitarism, 2 also had DI, two patients presented with CSF rhinorrhoea. There was a 100% improvement in the patients who presented with visual symptoms. Gross total resection was achieved in all 4 cases of craniopharyngiomas and 13 cases of pituitary adenomas. Postoperative CSF leak was seen in 4 patients who underwent re-exploration and sellar floor repair, 9 patients had postoperative Diabetes Insipidus (DI which was transient, the incidence of DI reduced towards the end of the study. There was a 25% decrease in the operating time towards the end of

  14. Learning curve tool applications in DOE materials management activities

    International Nuclear Information System (INIS)

    Lipinski, A.

    1994-01-01

    This paper will examine the application of learning curve theory, an economic theory that quantifies cost savings over time in a labor intensive process. Learning curve theory has been traditionally applied to a production process. This paper examines the application of learning curve theory in cost estimating of waste characterization in storage at a DOE facility

  15. Learning curve for laparoendoscopic single-site surgery for an experienced laparoscopic surgeon

    OpenAIRE

    Pao-Ling Torng; Kuan-Hung Lin; Jing-Shiang Hwang; Hui-Shan Liu; I-Hui Chen; Chi-Ling Chen; Su-Cheng Huang

    2013-01-01

    Objectives: To assess the learning curve and safety of laparoendoscopic single-site (LESS) surgery of gynecological surgeries. Materials and methods: Sixty-three women who underwent LESS surgery by a single experienced laparoscopic surgeon from February 2011 to August 2011 were included. Commercialized single-incision laparoscopic surgery homemade ports were used, along with conventional straight instruments. The learning curve has been defined as the additional surgical time with respect ...

  16. Medical learning curves and the Kantian ideal.

    Science.gov (United States)

    Le Morvan, P; Stock, B

    2005-09-01

    A hitherto unexamined problem for the "Kantian ideal" that one should always treat patients as ends in themselves, and never only as a means to other ends, is explored in this paper. The problem consists of a prima facie conflict between this Kantian ideal and the reality of medical practice. This conflict arises because, at least presently, medical practitioners can only acquire certain skills and abilities by practising on live, human patients, and given the inevitability and ubiquity of learning curves, this learning requires some patients to be treated only as a means to this end. A number of ways of attempting to establish the compatibility of the Kantian Ideal with the reality of medical practice are considered. Each attempt is found to be unsuccessful. Accordingly, until a way is found to reconcile them, we conclude that the Kantian ideal is inconsistent with the reality of medical practice.

  17. Technological change in energy systems. Learning curves, logistic curves and input-output coefficients

    International Nuclear Information System (INIS)

    Pan, Haoran; Koehler, Jonathan

    2007-01-01

    Learning curves have recently been widely adopted in climate-economy models to incorporate endogenous change of energy technologies, replacing the conventional assumption of an autonomous energy efficiency improvement. However, there has been little consideration of the credibility of the learning curve. The current trend that many important energy and climate change policy analyses rely on the learning curve means that it is of great importance to critically examine the basis for learning curves. Here, we analyse the use of learning curves in energy technology, usually implemented as a simple power function. We find that the learning curve cannot separate the effects of price and technological change, cannot reflect continuous and qualitative change of both conventional and emerging energy technologies, cannot help to determine the time paths of technological investment, and misses the central role of R and D activity in driving technological change. We argue that a logistic curve of improving performance modified to include R and D activity as a driving variable can better describe the cost reductions in energy technologies. Furthermore, we demonstrate that the top-down Leontief technology can incorporate the bottom-up technologies that improve along either the learning curve or the logistic curve, through changing input-output coefficients. An application to UK wind power illustrates that the logistic curve fits the observed data better and implies greater potential for cost reduction than the learning curve does. (author)

  18. Learning curve estimation techniques for nuclear industry

    International Nuclear Information System (INIS)

    Vaurio, Jussi K.

    1983-01-01

    Statistical techniques are developed to estimate the progress made by the nuclear industry in learning to prevent accidents. Learning curves are derived for accident occurrence rates based on actuarial data, predictions are made for the future, and compact analytical equations are obtained for the statistical accuracies of the estimates. Both maximum likelihood estimation and the method of moments are applied to obtain parameters for the learning models, and results are compared to each other and to earlier graphical and analytical results. An effective statistical test is also derived to assess the significance of trends. The models used associate learning directly to accidents, to the number of plants and to the cumulative number of operating years. Using as a data base nine core damage accidents in electricity-producing plants, it is estimated that the probability of a plant to have a serious flaw has decreased from 0.1 to 0.01 during the developmental phase of the nuclear industry. At the same time the frequency of accidents has decreased from 0.04 per reactor year to 0.0004 per reactor year

  19. LEARNING CURVE IN SINGLE-LEVEL MINIMALLY INVASIVE TLIF: EXPERIENCE OF A NEUROSURGEON

    Directory of Open Access Journals (Sweden)

    Samuel Romano-Feinholz

    Full Text Available ABSTRACT Objective: To describe the learning curve that shows the progress of a single neurosurgeon when performing single-level MI-TLIF. Methods: We included 99 consecutive patients who underwent single-level MI-TLIF by the same neurosurgeon (JASS. Patient’s demographic characteristics were analyzed. In addition, surgical time, intraoperative blood loss and hospital stay were evaluated. The learning curves were calculated with a piecewise regression model. Results: The mean age was 54.6 years. The learning curves showed an inverse relationship between the surgical experience and the variable analyzed, reaching an inflection point for surgical time in case 43 and for blood loss in case 48. The mean surgical time was 203.3 minutes (interquartile range [IQR] 150-240 minutes, intraoperative bleeding was 97.4ml (IQR 40-100ml and hospital stay of four days (IQR 3-5 days. Conclusions: MI-TLIF is a very frequent surgical procedure due to its effectiveness and safety, which has shown similar results to open procedure. According to this study, the required learning curve is slightly higher than for open procedures, and is reached after about 45 cases.

  20. Environmental management by the learning curve

    International Nuclear Information System (INIS)

    Fehr, M.

    2003-01-01

    This is a futuristic appreciation of waste management challenges and their solution by means of good management models. A literature review, administrative initiatives, research results, and experiences from practice are combined in this study to render an evolutionary picture of the change in paradigm relative to municipal solid waste possible to occur between 2000 and 2025. The principal stages of progress in the 25 years studied were: the correct characterization of municipal solid waste as a function of geographical location and recycling potential, the divided collection model and its corresponding learning curve, correct opportunity cost accounting tools, and the generally admitted and accepted changeover of municipal solid waste treatment from a technical to a management problem. It is reported that as a result of this progress, the municipal landfill is a species in extinction. Regional landfills with long life spans are the rule in 2025

  1. Learning Curve Characteristics for Caesarean Section Among Associate Clinicians : A Prospective Study from Sierra Leone

    NARCIS (Netherlands)

    Waalewijn, B.P.; van Duinen, A.; Koroma, A. P.; Rijken, M. J.; Elhassein, M.; Bolkan, H. A.

    2017-01-01

    Background: In response to the high maternal mortality ratio, Sierra Leone has adopted an associate clinician postgraduate surgical task-sharing training programme. Little is known about learning curve characteristics for caesarean sections among associate clinicians. The aim of this study is to

  2. Statistical assessment of the learning curves of health technologies.

    Science.gov (United States)

    Ramsay, C R; Grant, A M; Wallace, S A; Garthwaite, P H; Monk, A F; Russell, I T

    2001-01-01

    was a case series of consecutive laparoscopic cholecystectomy procedures performed by ten surgeons; the third was randomised trial data derived from the laparoscopic procedure arm of a multicentre trial of groin hernia repair, supplemented by data from non-randomised operations performed during the trial. RESULTS - HEALTH TECHNOLOGY ASSESSMENT LITERATURE REVIEW: Of 4571 abstracts identified, 272 (6%) were later included in the study after review of the full paper. Some 51% of studies assessed a surgical minimal access technique and 95% were case series. The statistical method used most often (60%) was splitting the data into consecutive parts (such as halves or thirds), with only 14% attempting a more formal statistical analysis. The reporting of the studies was poor, with 31% giving no details of data collection methods. RESULTS - NON-HEALTH TECHNOLOGY ASSESSMENT LITERATURE SEARCH: Of 9431 abstracts assessed, 115 (1%) were deemed appropriate for further investigation and, of these, 18 were included in the study. All of the methods for complex data sets were identified in the non-clinical literature. These were discriminant analysis, two-stage estimation of learning rates, generalised estimating equations, multilevel models, latent curve models, time series models and stochastic parameter models. In addition, eight new shapes of learning curves were identified. RESULTS - TESTING OF STATISTICAL METHODS: No one particular shape of learning curve performed significantly better than another. The performance of 'operation time' as a proxy for learning differed between the three procedures. Multilevel modelling using the laparoscopic cholecystectomy data demonstrated and measured surgeon-specific and confounding effects. The inclusion of non-randomised cases, despite the possible limitations of the method, enhanced the interpretation of learning effects. CONCLUSIONS - HEALTH TECHNOLOGY ASSESSMENT LITERATURE REVIEW: The statistical methods used for assessing learning effects

  3. Automated Blazar Light Curves Using Machine Learning

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, Spencer James [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2017-07-27

    This presentation describes a problem and methodology pertaining to automated blazar light curves. Namely, optical variability patterns for blazars require the construction of light curves and in order to generate the light curves, data must be filtered before processing to ensure quality.

  4. Surgical treatment of double thoracic adolescent idiopathic scoliosis with a rigid proximal thoracic curve.

    Science.gov (United States)

    Sudo, Hideki; Abe, Yuichiro; Abumi, Kuniyoshi; Iwasaki, Norimasa; Ito, Manabu

    2016-02-01

    There is limited consensus on the optimal surgical strategy for double thoracic adolescent idiopathic scoliosis (AIS). Recent studies have reported that pedicle screw constructs to maximize scoliosis correction cause further thoracic spine lordosis. The objective of this study was to apply a new surgical technique for double thoracic AIS with rigid proximal thoracic (PT) curves and assess its clinical outcomes. Twenty one consecutive patients with Lenke 2 AIS and a rigid PT curve (Cobb angle ≥30º on side-bending radiographs, flexibility ≤30 %) treated with the simultaneous double-rod rotation technique (SDRRT) were included. In this technique, a temporary rod is placed at the concave side of the PT curve. Then, distraction force is applied to correct the PT curve, which reforms a sigmoid double thoracic curve into an approximate single thoracic curve. As a result, the PT curve is typically converted from an apex left to an apex right curve before applying the correction rod for PT and main thoracic curve. All patients were followed for at least 2 years (average 2.7 years). The average main thoracic and PT Cobb angle correction rate at the final follow-up was 74.7 and 58.0 %, respectively. The average preoperative T5-T12 thoracic kyphosis was 9.3°, which improved significantly to 19.0° (p corrected using SDRRT for Lenke 2 AIS with a rigid PT curve.

  5. Shaping the learning curve: epigenetic dynamics in neural plasticity

    Directory of Open Access Journals (Sweden)

    Zohar Ziv Bronfman

    2014-07-01

    Full Text Available A key characteristic of learning and neural plasticity is state-dependent acquisition dynamics reflected by the non-linear learning curve that links increase in learning with practice. Here we propose that the manner by which epigenetic states of individual cells change during learning contributes to the shape of the neural and behavioral learning curve. We base our suggestion on recent studies showing that epigenetic mechanisms such as DNA methylation, histone acetylation and RNA-mediated gene regulation are intimately involved in the establishment and maintenance of long-term neural plasticity, reflecting specific learning-histories and influencing future learning. Our model, which is the first to suggest a dynamic molecular account of the shape of the learning curve, leads to several testable predictions regarding the link between epigenetic dynamics at the promoter, gene-network and neural-network levels. This perspective opens up new avenues for therapeutic interventions in neurological pathologies.

  6. Quantifying surgical complexity with machine learning: looking beyond patient factors to improve surgical models.

    Science.gov (United States)

    Van Esbroeck, Alexander; Rubinfeld, Ilan; Hall, Bruce; Syed, Zeeshan

    2014-11-01

    To investigate the use of machine learning to empirically determine the risk of individual surgical procedures and to improve surgical models with this information. American College of Surgeons National Surgical Quality Improvement Program (ACS NSQIP) data from 2005 to 2009 were used to train support vector machine (SVM) classifiers to learn the relationship between textual constructs in current procedural terminology (CPT) descriptions and mortality, morbidity, Clavien 4 complications, and surgical-site infections (SSI) within 30 days of surgery. The procedural risk scores produced by the SVM classifiers were validated on data from 2010 in univariate and multivariate analyses. The procedural risk scores produced by the SVM classifiers achieved moderate-to-high levels of discrimination in univariate analyses (area under receiver operating characteristic curve: 0.871 for mortality, 0.789 for morbidity, 0.791 for SSI, 0.845 for Clavien 4 complications). Addition of these scores also substantially improved multivariate models comprising patient factors and previously proposed correlates of procedural risk (net reclassification improvement and integrated discrimination improvement: 0.54 and 0.001 for mortality, 0.46 and 0.011 for morbidity, 0.68 and 0.022 for SSI, 0.44 and 0.001 for Clavien 4 complications; P risk for individual procedures. This information can be measured in an entirely data-driven manner and substantially improves multifactorial models to predict postoperative complications. Copyright © 2014 Elsevier Inc. All rights reserved.

  7. Virtual reality cataract surgery training: learning curves and concurrent validity.

    Science.gov (United States)

    Selvander, Madeleine; Åsman, Peter

    2012-08-01

    To investigate initial learning curves on a virtual reality (VR) eye surgery simulator and whether achieved skills are transferable between tasks. Thirty-five medical students were randomized to complete ten iterations on either the VR Caspulorhexis module (group A) or the Cataract navigation training module (group B) and then two iterations on the other module. Learning curves were compared between groups. The second Capsulorhexis video was saved and evaluated with the performance rating tool Objective Structured Assessment of Cataract Surgical Skill (OSACSS). The students' stereoacuity was examined. Both groups demonstrated significant improvements in performance over the 10 iterations: group A for all parameters analysed including score (p < 0.0001), time (p < 0.0001) and corneal damage (p = 0.0003), group B for time (p < 0.0001), corneal damage (p < 0.0001) but not for score (p = 0.752). Training on one module did not improve performance on the other. Capsulorhexis score correlated significantly with evaluation of the videos using the OSACSS performance rating tool. For stereoacuity < and ≥120 seconds of arc, sum of both modules' second iteration score was 73.5 and 41.0, respectively (p = 0.062). An initial rapid improvement in performance on a simulator with repeated practice was shown. For capsulorhexis, 10 iterations with only simulator feedback are not enough to reach a plateau for overall score. Skills transfer between modules was not found suggesting benefits from training on both modules. Stereoacuity may be of importance in the recruitment and training of new cataract surgeons. Additional studies are needed to investigate this further. Concurrent validity was found for Capsulorhexis module. © 2010 The Authors. Acta Ophthalmologica © 2010 Acta Ophthalmologica Scandinavica Foundation.

  8. Training in robotics: The learning curve and contemporary concepts in training.

    Science.gov (United States)

    Bach, Christian; Miernik, Arkadiusz; Schönthaler, Martin

    2014-03-01

    To define the learning curve of robot-assisted laparoscopic surgery for prostatectomy (RALP) and upper tract procedures, and show the differences between the classical approach to training and the new concept of parallel learning. This mini-review is based on the results of a Medline search using the keywords 'da Vinci', 'robot-assisted laparoscopic surgery', 'training', 'teaching' and 'learning curve'. For RALP and robot-assisted upper tract surgery, a learning curve of 8-150 procedures is quoted, with most articles proposing that 30-40 cases are needed to carry out the procedure safely. There is no consensus about which endpoints should be measured. In the traditional proctored training model, the surgeon learns the procedure linearly, following the sequential order of the surgical steps. A more recent approach is to specify the relative difficulty of each step and to train the surgeon simultaneously in several steps of equal difficulty. The entire procedure is only performed after all the steps are mastered in a timely manner. Recently, a 'warm-up' before robotic surgery has been shown to be beneficial for successful surgery in the operating room. There is no clear definition of the duration of the effective learning curve for RALP and robotic upper tract surgery. The concept of stepwise, parallel learning has the potential to accelerate the learning process and to make sure that initial cases are not too long. It can also be assumed that a preoperative 'warm up' could help significantly to improve the progress of the trainee.

  9. Climbing the health learning curve together | IDRC - International ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    2011-01-25

    Jan 25, 2011 ... Climbing the health learning curve together ... Many of the projects are creating master's programs at their host universities ... Formerly based in the high Arctic, Atlantis is described by Dr Martin Forde of St George's University ...

  10. Implementation Learning and Forgetting Curve to Scheduling in Garment Industry

    Science.gov (United States)

    Muhamad Badri, Huda; Deros, Baba Md; Syahri, M.; Saleh, Chairul; Fitria, Aninda

    2016-02-01

    The learning curve shows the relationship between time and the cumulative number of units produced which using the mathematical description on the performance of workers in performing repetitive works. The problems of this study is level differences in the labors performance before and after the break which affects the company's production scheduling. The study was conducted in the garment industry, which the aims is to predict the company production scheduling using the learning curve and forgetting curve. By implementing the learning curve and forgetting curve, this paper contributes in improving the labors performance that is in line with the increase in maximum output 3 hours productive before the break are 15 unit product with learning curve percentage in the company is 93.24%. Meanwhile, the forgetting curve improving maximum output 3 hours productive after the break are 11 unit product with the percentage of forgetting curve in the company is 92.96%. Then, the obtained 26 units product on the productive hours one working day is used as the basic for production scheduling.

  11. An appraisal of the learning curve in robotic general surgery.

    Science.gov (United States)

    Pernar, Luise I M; Robertson, Faith C; Tavakkoli, Ali; Sheu, Eric G; Brooks, David C; Smink, Douglas S

    2017-11-01

    Robotic-assisted surgery is used with increasing frequency in general surgery for a variety of applications. In spite of this increase in usage, the learning curve is not yet defined. This study reviews the literature on the learning curve in robotic general surgery to inform adopters of the technology. PubMed and EMBASE searches yielded 3690 abstracts published between July 1986 and March 2016. The abstracts were evaluated based on the following inclusion criteria: written in English, reporting original work, focus on general surgery operations, and with explicit statistical methods. Twenty-six full-length articles were included in final analysis. The articles described the learning curves in colorectal (9 articles, 35%), foregut/bariatric (8, 31%), biliary (5, 19%), and solid organ (4, 15%) surgery. Eighteen of 26 (69%) articles report single-surgeon experiences. Time was used as a measure of the learning curve in all studies (100%); outcomes were examined in 10 (38%). In 12 studies (46%), the authors identified three phases of the learning curve. Numbers of cases needed to achieve plateau performance were wide-ranging but overlapping for different kinds of operations: 19-128 cases for colorectal, 8-95 for foregut/bariatric, 20-48 for biliary, and 10-80 for solid organ surgery. Although robotic surgery is increasingly utilized in general surgery, the literature provides few guidelines on the learning curve for adoption. In this heterogeneous sample of reviewed articles, the number of cases needed to achieve plateau performance varies by case type and the learning curve may have multiple phases as surgeons add more complex cases to their case mix with growing experience. Time is the most common determinant for the learning curve. The literature lacks a uniform assessment of outcomes and complications, which would arguably reflect expertise in a more meaningful way than time to perform the operation alone.

  12. Taking the brakes off the learning curve.

    Science.gov (United States)

    Gheysen, Freja; Lasne, Gabriel; Pélégrini-Issac, Mélanie; Albouy, Genevieve; Meunier, Sabine; Benali, Habib; Doyon, Julien; Popa, Traian

    2017-03-01

    Motor learning is characterized by patterns of cerebello-striato-cortical activations shifting in time, yet the early dynamic and function of these activations remains unclear. Five groups of subjects underwent either continuous or intermittent theta-burst stimulation of one cerebellar hemisphere, or no stimulation just before learning a new motor sequence during fMRI scanning. We identified three phases during initial learning: one rapid, one slow, and one quasi-asymptotic performance phase. These phases were not changed by left cerebellar stimulation. Right cerebellar inhibition, however, accelerated learning and enhanced brain activation in critical motor learning-related areas during the first phase, continuing with reduced brain activation but high-performance in late phase. Right cerebellar excitation did not affect the early learning process, but slowed learning significantly in late phase, along with increased brain activation. We conclude that the right cerebellum is a key factor coordinating other neuronal loops in the early acquisition of an explicit motor sequential skill. Hum Brain Mapp 38:1676-1691, 2017. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

  13. Learning style preferences of surgical residency applicants.

    Science.gov (United States)

    Kim, Roger H; Gilbert, Timothy

    2015-09-01

    The learning style preferences of general surgery residents have been previously reported; there is evidence that residents who prefer read/write learning styles perform better on the American Board of Surgery In-Training Examination (ABSITE). However, little is known regarding the learning style preferences of applicants to general surgery residency and their impact on educational outcomes. In this study, the preferred learning styles of surgical residency applicants were determined. We hypothesized that applicant rank data are associated with specific learning style preferences. The Fleming VARK learning styles inventory was offered to all general surgery residency applicants that were interviewed at a university hospital-based program. The VARK model categorizes learners as visual (V), aural (A), read/write (R), kinesthetic (K), or multimodal (MM). Responses on the inventory were scored to determine the preferred learning style for each applicant. Applicant data, including United States Medical Licensing Examination (USMLE) scores, class rank, interview score, and overall final applicant ranking, were examined for association with preferred learning styles. Sixty-seven applicants were interviewed. Five applicants were excluded due to not completing the VARK inventory or having incomplete applicant data. The remaining 62 applicants (92%) were included for analysis. Most applicants (57%) had a multimodal preference. Sixty-nine percent of all applicants had some degree of preference for kinesthetic learning. There were statistically significant differences between applicants of different learning styles in terms of USMLE step 1 scores (P = 0.001) and USMLE step 2 clinical knowledge scores (P = 0.01), but not for class ranks (P = 0.27), interview scores (P = 0.20), or final ranks (P = 0.14). Multiple comparison analysis demonstrated that applicants with aural preferences had higher USMLE 1 scores (233.2) than those with kinesthetic (211.8, P = 0.005) or multimodal

  14. The learning curve of laparoscopic treatment of rectal cancer does not increase morbidity.

    Science.gov (United States)

    Luján, Juan; Gonzalez, Antonio; Abrisqueta, Jesús; Hernandez, Quiteria; Valero, Graciela; Abellán, Israel; Frutos, María Dolores; Parrilla, Pascual

    2014-01-01

    The treatment of rectal cancer via laparoscopy is controversial due to its technical complexity. Several randomized prospective studies have demonstrated clear advantages for the patient with similar oncological results to those of open surgery, although during the learning of this surgical technique there may be an increase in complications and a worse prognosis. Our aim is to analyze how the learning curve for rectal cancer via laparoscopy influences intra- and postoperative results and oncological markers. A retrospective review was conducted of the first 120 patients undergoing laparoscopic surgery for rectal neoplasia. The operations were performed by the same surgical team with a wide experience in the treatment of open colorectal cancer and qualified to perform advanced laparoscopic surgery. We analyzed sex, ASA, tumour location, neoadjuvant treatment, surgical technique, operating time, conversion, postoperative complications, length of hospital stay, number of lymph nodes, stage and involvement of margins. Significant differences were observed with regard to surgical time (224 min in the first group, 204 min in the second group), with a higher rate of conversion in the first group (22.5%) than in the second (11.3%). No significant differences were noted for rate of conservative sphincter surgery, length of hospital stay, post-surgical complications, number of affected/isolated lymph nodes or affected circumferential and distal margins. It is possible to learn this complex surgical technique without compromising the patient's safety and oncological outcome. Copyright © 2013 AEC. Published by Elsevier Espana. All rights reserved.

  15. Fast algorithm selection using learning curves

    NARCIS (Netherlands)

    Rijn, van J.N.; Abdulrahman, S.M.; Brazdil, P.; Vanschoren, J.; Fromont, E.; De Bie, T.; Leeuwen, van M.

    2015-01-01

    One of the challenges in Machine Learning to find a classifier and parameter settings that work well on a given dataset. Evaluating all possible combinations typically takes too much time, hence many solutions have been proposed that attempt to predict which classifiers are most promising to try. As

  16. Learning curve for intracranial angioplasty and stenting in single center.

    Science.gov (United States)

    Cai, Qiankun; Li, Yongkun; Xu, Gelin; Sun, Wen; Xiong, Yunyun; Sun, Wenshan; Bao, Yuanfei; Huang, Xianjun; Zhang, Yao; Zhou, Lulu; Zhu, Wusheng; Liu, Xinfeng

    2014-01-01

    To identify the specific caseload to overcome learning curve effect based on data from consecutive patients treated with Intracranial Angioplasty and Stenting (IAS) in our center. The Stenting and Aggressive Medical Management for Preventing Recurrent Stroke and Intracranial Stenosis trial was prematurely terminated owing to the high rate of periprocedural complications in the endovascular arm. To date, there are no data available for determining the essential caseload sufficient to overcome the learning effect and perform IAS with an acceptable level of complications. Between March 2004 and May 2012, 188 consecutive patients with 194 lesions who underwent IAS were analyzed retrospectively. The outcome variables used to assess the learning curve were periprocedural complications (included transient ischemic attack, ischemic stroke, vessel rupture, cerebral hyperperfusion syndrome, and vessel perforation). Multivariable logistic regression analysis was employed to illustrate the existence of learning curve effect on IAS. A risk-adjusted cumulative sum chart was performed to identify the specific caseload to overcome learning curve effect. The overall rate of 30-days periprocedural complications was 12.4% (24/194). After adjusting for case-mix, multivariate logistic regression analysis showed that operator experience was an independent predictor for periprocedural complications. The learning curve of IAS to overcome complications in a risk-adjusted manner was 21 cases. Operator's level of experience significantly affected the outcome of IAS. Moreover, we observed that the amount of experience sufficient for performing IAS in our center was 21 cases. Copyright © 2013 Wiley Periodicals, Inc.

  17. Parameters leading to a successful radiographic outcome following surgical treatment for Lenke 2 curves.

    Science.gov (United States)

    Koller, Heiko; Meier, Oliver; McClung, Anna; Hitzl, Wolfgang; Mayer, Michael; Sucato, Daniel

    2015-07-01

    In Lenke 2 curves, there are conflicting data when to include the PTC into the fusion. Studies focusing on Lenke 2 curves are scant. The number of patients with significant postoperative shoulder height difference (SHD) or trunk shift (TS) is as high as 30 % indicating further research. Therefore, the purpose of the current study was to improve understanding of curve resolution and shoulder balance following surgical correction of Lenke 2 curves as well as the identification of radiographic parameters predicting postoperative curve resolution, shoulder and trunk balance in perspective of inclusion/exclusion of the proximal thoracic curve (PTC). This is a retrospective study of a 158 Lenke 2 curves. Serial radiographs were analyzed for the main thoracic curve (MTC), PTC, and lumbar curve (LC), SHD, clavicle angle (CA), T-1 tilt, deviation of the central sacral vertical line (CSVL) off the C7 plumb line.Patients were stratified whether the PTC was included in the fusion (+PTC group, n = 60) or not (-PTC group, n = 98). Intergroup results were studied. Compensatory mechanisms for SHD were studied in detail. Adding-on distally was defined as an increase of the lowest instrumented vertebra adjacent disc angle (LIVDA) >3°. Stepwise regression analyses were performed to establish predictive radiographic parameters. At follow-up averaging 24 months significant differences between the +PTC and -PTC group existed for the PTC (24° vs 28°, p 5° (27 vs 53 %, p 2 cm) was 9 (6 %): 7 in the -PTC vs 2 in the +PTC group (p = .03). Utilization of compensatory mechanisms (99 vs 83 %, p Statistics showed postoperative SHD improvement in both the +PTC and -PTC groups. There were no significant differences regarding SHD, CA and T1-Tilt between groups. However, only in the -PTC group, a significant change between postoperative and follow-up SHD existed (p = .02). Statistics identified a preoperative 'left shoulder up' (p statistical model only for the -PTC group showed 9 parameters

  18. Colorectal Stenting in Malignant Large Bowel Obstruction: The Learning Curve

    Directory of Open Access Journals (Sweden)

    D. Williams

    2011-01-01

    Full Text Available Aim. Self-expanding metal stents (SEMSs are increasingly used for the palliation of metastatic colorectal cancer and as a bridge to surgery for obstructing tumours. This case series analyses the learning curve and changes in practice of colorectal stenting over a three year period. Methods. A study of 40 patients who underwent placement of SEMS for the management of colorectal cancer. Patients spanned the learning curve of a single surgeon endoscopist. Results. Technical success rates increased from 82% initially, using an average of 1.7 stents per procedure, to a 94% success rate where all patients were stented using a single stent. There has been a change in practice from elective palliative stenting toward emergency preoperative stenting. Conclusion. There is a steep learning curve for the use of SEMS in the management of malignant colorectal bowel obstruction. We suggest that at least 20 cases are required for an operator to be considered experienced.

  19. Detection of player learning curve in a car driving game

    NARCIS (Netherlands)

    Bontchev, Boyan; Vassileva, Dessislava

    2018-01-01

    Detection of learning curves of player metrics is very important for the serious (or so called applied) games, because it provides an indicator representing how players master the game tasks by acquiring cognitive abilities, knowledge, and necessary skills for solving the game challenges. Real

  20. Application of Learning Curves for Didactic Model Evaluation: Case Studies

    Directory of Open Access Journals (Sweden)

    Felix Mödritscher

    2013-01-01

    Full Text Available The success of (online courses depends, among other factors, on the underlying didactical models which have always been evaluated with qualitative and quantitative research methods. Several new evaluation techniques have been developed and established in the last years. One of them is ‘learning curves’, which aim at measuring error rates of users when they interact with adaptive educational systems, thereby enabling the underlying models to be evaluated and improved. In this paper, we report how we have applied this new method to two case studies to show that learning curves are useful to evaluate didactical models and their implementation in educational platforms. Results show that the error rates follow a power law distribution with each additional attempt if the didactical model of an instructional unit is valid. Furthermore, the initial error rate, the slope of the curve and the goodness of fit of the curve are valid indicators for the difficulty level of a course and the quality of its didactical model. As a conclusion, the idea of applying learning curves for evaluating didactical model on the basis of usage data is considered to be valuable for supporting teachers and learning content providers in improving their online courses.

  1. A uniquely shaped rod improves curve correction in surgical treatment of adolescent idiopathic scoliosis

    DEFF Research Database (Denmark)

    Gehrchen, Poul Martin; Ohrt-Nissen, Søren; Hallager, Dennis Winge

    2016-01-01

    . Posterior fusion using all pedicle screw instrumentation has become the standard for the surgical treatment of AIS. Traditionally, the rod is circular in the cross-sectional plane. Recent biomechanical studies suggest that a beam-like structure of the rod may enhance the stiffness of the construct...... correction, sagittal balance, or coronal balance (P>0.058). A postoperative decrease in thoracic kyphosis was seen with no significant difference between groups. Median T5-T12 change was -7° versus -3° for BR and CR, respectively (P=0.051).  Conclusion. A BR design results in a significantly better curve...

  2. Use and limitations of learning curves for energy technology policy: A component-learning hypothesis

    International Nuclear Information System (INIS)

    Ferioli, F.; Schoots, K.; Zwaan, B.C.C. van der

    2009-01-01

    In this paper, we investigate the use of learning curves for the description of observed cost reductions for a variety of energy technologies. Starting point of our analysis is the representation of energy processes and technologies as the sum of different components. While we recognize that in many cases 'learning-by-doing' may improve the overall costs or efficiency of a technology, we argue that so far insufficient attention has been devoted to study the effects of single component improvements that together may explain an aggregated form of learning. Indeed, for an entire technology the phenomenon of learning-by-doing may well result from learning of one or a few individual components only. We analyze under what conditions it is possible to combine learning curves for single components to derive one comprehensive learning curve for the total product. The possibility that for certain technologies some components (e.g., the primary natural resources that serve as essential input) do not exhibit cost improvements might account for the apparent time dependence of learning rates reported in several studies (the learning rate might also change considerably over time depending on the data set considered, a crucial issue to be aware of when one uses the learning curve methodology). Such an explanation may have important consequences for the extent to which learning curves can be extrapolated into the future. This argumentation suggests that cost reductions may not continue indefinitely and that well-behaved learning curves do not necessarily exist for every product or technology. In addition, even for diffusing and maturing technologies that display clear learning effects, market and resource constraints can eventually significantly reduce the scope for further improvements in their fabrication or use. It appears likely that some technologies, such as wind turbines and photovoltaic cells, are significantly more amenable than others to industry-wide learning. For such

  3. The learning curve: implications of a quantitative analysis.

    Science.gov (United States)

    Gallistel, Charles R; Fairhurst, Stephen; Balsam, Peter

    2004-09-07

    The negatively accelerated, gradually increasing learning curve is an artifact of group averaging in several commonly used basic learning paradigms (pigeon autoshaping, delay- and trace-eye-blink conditioning in the rabbit and rat, autoshaped hopper entry in the rat, plus maze performance in the rat, and water maze performance in the mouse). The learning curves for individual subjects show an abrupt, often step-like increase from the untrained level of responding to the level seen in the well trained subject. The rise is at least as abrupt as that commonly seen in psychometric functions in stimulus detection experiments. It may indicate that the appearance of conditioned behavior is mediated by an evidence-based decision process, as in stimulus detection experiments. If the appearance of conditioned behavior is taken instead to reflect the increase in an underlying associative strength, then a negligible portion of the function relating associative strength to amount of experience is behaviorally visible. Consequently, rate of learning cannot be estimated from the group-average curve; the best measure is latency to the onset of responding, determined for each subject individually.

  4. Robotic partial nephrectomy - Evaluation of the impact of case mix on the procedural learning curve.

    Science.gov (United States)

    Roman, A; Ahmed, K; Challacombe, B

    2016-05-01

    Although Robotic partial nephrectomy (RPN) is an emerging technique for the management of small renal masses, this approach is technically demanding. To date, there is limited data on the nature and progression of the learning curve in RPN. To analyse the impact of case mix on the RPN LC and to model the learning curve. The records of the first 100 RPN performed, were analysed at our institution that were carried out by a single surgeon (B.C) (June 2010-December 2013). Cases were split based on their Preoperative Aspects and Dimensions Used for an Anatomical (PADUA) score into the following groups: 6-7, 8-9 and >10. Using a split group (20 patients in each group) and incremental analysis, the mean, the curve of best fit and R(2) values were calculated for each group. Of 100 patients (F:28, M:72), the mean age was 56.4 ± 11.9 years. The number of patients in each PADUA score groups: 6-7, 8-9 and >10 were 61, 32 and 7 respectively. An increase in incidence of more complex cases throughout the cohort was evident within the 8-9 group (2010: 1 case, 2013: 16 cases). The learning process did not significantly affect the proxies used to assess surgical proficiency in this study (operative time and warm ischaemia time). Case difficulty is an important parameter that should be considered when evaluating procedural learning curves. There is not one well fitting model that can be used to model the learning curve. With increasing experience, clinicians tend to operate on more difficult cases. Copyright © 2016 IJS Publishing Group Ltd. Published by Elsevier Ltd. All rights reserved.

  5. Training, Simulation, the Learning Curve, and How to Reduce Complications in Urology.

    Science.gov (United States)

    Brunckhorst, Oliver; Volpe, Alessandro; van der Poel, Henk; Mottrie, Alexander; Ahmed, Kamran

    2016-04-01

    Urology is at the forefront of minimally invasive surgery to a great extent. These procedures produce additional learning challenges and possess a steep initial learning curve. Training and assessment methods in surgical specialties such as urology are known to lack clear structure and often rely on differing operative flow experienced by individuals and institutions. This article aims to assess current urology training modalities, to identify the role of simulation within urology, to define and identify the learning curves for various urologic procedures, and to discuss ways to decrease complications in the context of training. A narrative review of the literature was conducted through December 2015 using the PubMed/Medline, Embase, and Cochrane Library databases. Evidence of the validity of training methods in urology includes observation of a procedure, mentorship and fellowship, e-learning, and simulation-based training. Learning curves for various urologic procedures have been recommended based on the available literature. The importance of structured training pathways is highlighted, with integration of modular training to ensure patient safety. Valid training pathways are available in urology. The aim in urology training should be to combine all of the available evidence to produce procedure-specific curricula that utilise the vast array of training methods available to ensure that we continue to improve patient outcomes and reduce complications. The current evidence for different training methods available in urology, including simulation-based training, was reviewed, and the learning curves for various urologic procedures were critically analysed. Based on the evidence, future pathways for urology curricula have been suggested to ensure that patient safety is improved. Copyright © 2016 European Association of Urology. Published by Elsevier B.V. All rights reserved.

  6. Machine Learning Techniques for Stellar Light Curve Classification

    Science.gov (United States)

    Hinners, Trisha A.; Tat, Kevin; Thorp, Rachel

    2018-07-01

    We apply machine learning techniques in an attempt to predict and classify stellar properties from noisy and sparse time-series data. We preprocessed over 94 GB of Kepler light curves from the Mikulski Archive for Space Telescopes (MAST) to classify according to 10 distinct physical properties using both representation learning and feature engineering approaches. Studies using machine learning in the field have been primarily done on simulated data, making our study one of the first to use real light-curve data for machine learning approaches. We tuned our data using previous work with simulated data as a template and achieved mixed results between the two approaches. Representation learning using a long short-term memory recurrent neural network produced no successful predictions, but our work with feature engineering was successful for both classification and regression. In particular, we were able to achieve values for stellar density, stellar radius, and effective temperature with low error (∼2%–4%) and good accuracy (∼75%) for classifying the number of transits for a given star. The results show promise for improvement for both approaches upon using larger data sets with a larger minority class. This work has the potential to provide a foundation for future tools and techniques to aid in the analysis of astrophysical data.

  7. Systematic review of learning curves for minimally invasive abdominal surgery: a review of the methodology of data collection, depiction of outcomes, and statistical analysis.

    Science.gov (United States)

    Harrysson, Iliana J; Cook, Jonathan; Sirimanna, Pramudith; Feldman, Liane S; Darzi, Ara; Aggarwal, Rajesh

    2014-07-01

    To determine how minimally invasive surgical learning curves are assessed and define an ideal framework for this assessment. Learning curves have implications for training and adoption of new procedures and devices. In 2000, a review of the learning curve literature was done by Ramsay et al and it called for improved reporting and statistical evaluation of learning curves. Since then, a body of literature is emerging on learning curves but the presentation and analysis vary. A systematic search was performed of MEDLINE, EMBASE, ISI Web of Science, ERIC, and the Cochrane Library from 1985 to August 2012. The inclusion criteria are minimally invasive abdominal surgery formally analyzing the learning curve and English language. 592 (11.1%) of the identified studies met the selection criteria. Time is the most commonly used proxy for the learning curve (508, 86%). Intraoperative outcomes were used in 316 (53%) of the articles, postoperative outcomes in 306 (52%), technical skills in 102 (17%), and patient-oriented outcomes in 38 (6%) articles. Over time, there was evidence of an increase in the relative amount of laparoscopic and robotic studies (P statistical evidence of a change in the complexity of analysis (P = 0.121). Assessment of learning curves is needed to inform surgical training and evaluate new clinical procedures. An ideal analysis would account for the degree of complexity of individual cases and the inherent differences between surgeons. There is no single proxy that best represents the success of surgery, and hence multiple outcomes should be collected.

  8. Carbon Intensities of Economies from the Perspective of Learning Curves

    Directory of Open Access Journals (Sweden)

    Henrique Pacini

    2014-03-01

    Full Text Available While some countries have achieved considerable development, many others still lack accessto the goods and services considered standard in the modern society. As CO2 emissions and development are often correlated, this paper employs the theoretical background of the Environmental Kuznets Curve (EKC and the learning curves toolkit to analyze how carbon intensities have changed as countries move towards higher development (and cumulative wealth levels. The EKC concept is then tested with the methodology of learning curves for the period between 1971 and 2010, so as to capture a dynamic picture of emissions trends and development. Results of both analyses reveal that empirical data fails to provide direct evidence of an EKC for emissions and development. The data does show, however, an interesting pattern in the dispersion of emissions levels for countries within the same HDI categories. While data does not show that countries grow more polluting during intermediary development stages, it does provide evidence that countries become more heterogeneous in their emission intensities as they develop, later re-converging to lower emission intensities at higher HDI levels. Learning rates also indicate heterogeneity among developing countries and relative convergence among developed countries. Given the heterogeneity of development paths among countries, the experiences of those which are managing to develop at low carbon intensities can prove valuable examples for ongoing efforts in climate change mitigation, especially in the developing world.

  9. Beyond the learning curve: factors influencing cost reductions in photovoltaics

    International Nuclear Information System (INIS)

    Nemet, Gregory F.

    2006-01-01

    The extent and timing of cost-reducing improvements in low-carbon energy systems are important sources of uncertainty in future levels of greenhouse-gas emissions. Models that assess the costs of climate change mitigation policy, and energy policy in general, rely heavily on learning curves to include technology dynamics. Historically, no energy technology has changed more dramatically than photovoltaics (PV), the cost of which has declined by a factor of nearly 100 since the 1950s. Which changes were most important in accounting for the cost reductions that have occurred over the past three decades? Are these results consistent with the notion that learning from experience drove technical change? In this paper, empirical data are assembled to populate a simple model identifying the most important factors affecting the cost of PV. The results indicate that learning from experience, the theoretical mechanism used to explain learning curves, only weakly explains change in the most important factors-plant size, module efficiency, and the cost of silicon. Ways in which the consideration of a broader set of influences, such as technical barriers, industry structure, and characteristics of demand, might be used to inform energy technology policy are discussed

  10. Displays mounted on cutting blocks reduce the learning curve in navigated total knee arthroplasty.

    Science.gov (United States)

    Schnurr, Christoph; Eysel, Peer; König, Dietmar Pierre

    2011-01-01

    The use of computer navigation in total knee arthroplasty (TKA) improves the implant alignment but increases the operation time. Studies have shown that the operation time is further prolonged due to the surgeon's learning curve, and longer operation times have been associated with higher morbidity risks. It has been our hypothesis that an improvement in the human-machine interface might reduce the time required during the learning curve. Accordingly, we asked whether the use of navigation devices with a display fixed on the surgical instruments would reduce the operation time in navigated TKAs performed by navigation beginners. Thirty medical students were randomized and used two navigation devices in rotation: these were the Kolibri® device with an external display and the Dash® device with a display that was fixed on the cutting blocks. The time for adjustment of the tibial and femoral cutting blocks on knee models while using these devices was measured. A significant time reduction was demonstration when the Dash® device was used: The time reduction was 21% for the tibial block (p = 0.007), 40% for the femoral block (p learning curve may be diminished.

  11. A New Proposal for Learning Curve of TEP Inguinal Hernia Repair: Ability to Complete Operation Endoscopically as a First Phase of Learning Curve

    Directory of Open Access Journals (Sweden)

    Mustafa Hasbahceci

    2014-01-01

    Full Text Available Background. The exact nature of learning curve of totally extraperitoneal inguinal hernia and the number required to master this technique remain controversial. Patients and Methods. We present a retrospective review of a single surgeon experience on patients who underwent totally extraperitoneal inguinal hernia repair. Results. There were 42 hernias (22 left- and 20 right-sided in 39 patients with a mean age of 48.8±15.1 years. Indirect, direct, and combined hernias were present in 18, 12, and 12 cases, respectively. The mean operative time was 55.1±22.8 minutes. Peritoneal injury occurred in 9 cases (21.4%. Conversion to open surgery was necessitated in 7 cases (16.7%. After grouping of all patients into two groups as cases between 1–21 and 22–42, it was seen that the majority of peritoneal injuries (7 out of 9, 77.8%, P=0.130 and all conversions (P=0.001 occurred in the first 21 cases. Conclusions. Learning curve of totally extraperitoneal inguinal hernia repair can be divided into two consequent steps: immediate and late. At least 20 operations are required for gaining anatomical knowledge and surgical pitfalls based on the ability to perform this operation without conversion during immediate phase.

  12. Learning curve analysis of mitral valve repair using telemanipulative technology.

    Science.gov (United States)

    Charland, Patrick J; Robbins, Tom; Rodriguez, Evilio; Nifong, Wiley L; Chitwood, Randolph W

    2011-08-01

    To determine if the time required to perform mitral valve repairs using telemanipulation technology decreases with experience and how that decrease is influenced by patient and procedure variables. A single-center retrospective review was conducted using perioperative and outcomes data collected contemporaneously on 458 mitral valve repair surgeries using telemanipulative technology. A regression model was constructed to assess learning with this technology and predict total robot time using multiple predictive variables. Statistical analysis was used to determine if models were significantly useful, to rule out correlation between predictor variables, and to identify terms that did not contribute to the prediction of total robot time. We found a statistically significant learning curve (P learning percentage∗ derived from total robot times† for the first 458 recorded cases of mitral valve repair using telemanipulative technology is 95% (R(2) = .40). More than one third of the variability in total robot time can be explained through our model using the following variables: type of repair (chordal procedures, ablations, and leaflet resections), band size, use of clips alone in band implantation, and the presence of a fellow at bedside (P Learning in mitral valve repair surgery using telemanipulative technology occurs at the East Carolina Heart Institute according to a logarithmic curve, with a learning percentage of 95%. From our regression output, we can make an approximate prediction of total robot time using an additive model. These metrics can be used by programs for benchmarking to manage the implementation of this new technology, as well as for capacity planning, scheduling, and capital budget analysis. Copyright © 2011 The American Association for Thoracic Surgery. All rights reserved.

  13. Effective and efficient learning in the operating theater with intraoperative video-enhanced surgical procedure training

    OpenAIRE

    van Det, M.J.; Meijerink, W.J.; Hoff, C.; Middel, B.; Pierie, J.P.

    2013-01-01

    INtraoperative Video Enhanced Surgical procedure Training (INVEST) is a new training method designed to improve the transition from basic skills training in a skills lab to procedural training in the operating theater. Traditionally, the master-apprentice model (MAM) is used for procedural training in the operating theater, but this model lacks uniformity and efficiency at the beginning of the learning curve. This study was designed to investigate the effectiveness and efficiency of INVEST co...

  14. Yield curve and Recession Forecasting in a Machine Learning Framework

    OpenAIRE

    Theophilos Papadimitriou; Periklis Gogas; Maria Matthaiou; Efthymia Chrysanthidou

    2014-01-01

    In this paper, we investigate the forecasting ability of the yield curve in terms of the U.S. real GDP cycle. More specifically, within a Machine Learning (ML) framework, we use data from a variety of short (treasury bills) and long term interest rates (bonds) for the period from 1976:Q3 to 2011:Q4 in conjunction with the real GDP for the same period, to create a model that can successfully forecast output fluctuations (inflation and output gaps) around its long-run trend. We focus our attent...

  15. [Is local bone graft sufficient to maintain the surgical correction in adolescent idiopathic scoliosis curves?].

    Science.gov (United States)

    Mardomingo, A; Sánchez-Mariscal, F; Alvarez, P; Pizones, J; Zúñica, L; Izquierdo, E

    2013-01-01

    The purpose of this study was to compare postoperative clinical and radiological results in adolescent idiopathic scoliosis curves treated by posterior arthrodesis using autogenous bone graft from iliac crest (CI) versus only local autograft bone (HL). A retrospective matched cohort study was conducted on 73 patients (CI n=37 and HL n=36) diagnosed with adolescent idiopathic scoliosis and treated surgically by posterior arthrodesis. The mean post-operative follow-up was 126 months in the CI group vs. 66 months in the HL group. The radiographic data collected consisted of preoperative, postoperative, and final follow-up antero-posterior and lateral full-length radiographs. Loss of correction and quality of arthrodesis were evaluated by comparing the scores obtained from the Spanish version of the SRS-22 questionnaire. There were significant differences in the post-operative results as regards the correction of the Cobb angle of the main curve (HL 61 ± 15% vs. CI 51 ± 14%, P<.004), however a greater loss of correction was found in the local bone group (CI 4.5 ± 7.3° vs. HL 8.5 ± 6.3°, P=.02). There were no significant differences as regards the correction of the Cobb angle of the main curve at the end of follow-up. There were no clinical differences between the two groups in the SRS-22 scores. At 5 years of follow-up, there was a statistically significant greater loss of radiographic correction at the end of final follow-up in the local bone graft group. However clinical differences were not observed as regards the SRS-22 scores. Copyright © 2013 SECOT. Published by Elsevier Espana. All rights reserved.

  16. Changing the Learning Curve in Novice Laparoscopists: Incorporating Direct Visualization into the Simulation Training Program.

    Science.gov (United States)

    Dawidek, Mark T; Roach, Victoria A; Ott, Michael C; Wilson, Timothy D

    A major challenge in laparoscopic surgery is the lack of depth perception. With the development and continued improvement of 3D video technology, the potential benefit of restoring 3D vision to laparoscopy has received substantial attention from the surgical community. Despite this, procedures conducted under 2D vision remain the standard of care, and trainees must become proficient in 2D laparoscopy. This study aims to determine whether incorporating 3D vision into a 2D laparoscopic simulation curriculum accelerates skill acquisition in novices. Postgraduate year-1 surgical specialty residents (n = 15) at the Schulich School of Medicine and Dentistry, at Western University were randomized into 1 of 2 groups. The control group practiced the Fundamentals of Laparoscopic Surgery peg-transfer task to proficiency exclusively under standard 2D laparoscopy conditions. The experimental group first practiced peg transfer under 3D direct visualization, with direct visualization of the working field. Upon reaching proficiency, this group underwent a perceptual switch, changing to standard 2D laparoscopy conditions, and once again trained to proficiency. Incorporating 3D direct visualization before training under standard 2D conditions significantly (p learning curves for each respective training protocol. An adaptive learning approach, which incorporates 3D direct visualization into a 2D laparoscopic simulation curriculum, accelerates skill acquisition. This is in contrast to previous work, possibly owing to the proficiency-based methodology employed, and has implications for resource savings in surgical training. Crown Copyright © 2016. Published by Elsevier Inc. All rights reserved.

  17. Learning curve of thyroid fine-needle aspiration biopsy.

    Science.gov (United States)

    Penín, Manuel; Martín, M Ángeles; San Millán, Beatriz; García, Juana

    2017-12-01

    Fine-needle aspiration biopsy (FNAB) is the reference procedure for thyroid nodule evaluation. Its main limitation are inadequate samples, which should be less than 20%. To analyze the learning curve of the procedure by comparing the results of a non-experienced endocrinologist (endocrinologist 2) to those of an experienced one (endocrinologist 1). Sixty FNABs were analyzed from February to June 2016. Each endocrinologist made 2punctures of every nodule in a random order. This order and the professional making every puncture were unknown to the pathologist who examined the samples. Endocrinologist 1 had a higher percentage of diagnoses than endocrinologist 2 (82% vs. 72%, P=.015). In the first 20 FNABs, the difference between both physicians was remarkable and statistically significant (80% vs. 50%, P=.047). In the following 20 FNABs, the difference narrowed and was not statistically significant (90% vs. 65%, P=.058). In the final 20 FNABs, the difference was minimal and not statistically significant (75% vs. 70%, P=.723). The learning curve of ultrasound-guided FNAB may be completed in a suitable environment by performing it at least 60 times. Although the guidelines recommend at least 3punctures per nodule, 2are enough to achieve an accurate percentage of diagnoses. Copyright © 2017 SEEN y SED. Publicado por Elsevier España, S.L.U. All rights reserved.

  18. Learning-curve estimation techniques for nuclear industry

    Energy Technology Data Exchange (ETDEWEB)

    Vaurio, J.K.

    1983-01-01

    Statistical techniques are developed to estimate the progress made by the nuclear industry in learning to prevent accidents. Learning curves are derived for accident occurrence rates based on acturial data, predictions are made for the future, and compact analytical equations are obtained for the statistical accuracies of the estimates. Both maximum likelihood estimation and the method of moments are applied to obtain parameters for the learning models, and results are compared to each other and to earlier graphical and analytical results. An effective statistical test is also derived to assess the significance of trends. The models used associate learning directly to accidents, to the number of plants and to the cumulative number of operating years. Using as a data base nine core damage accidents in electricity-producing plants, it is estimated that the probability of a plant to have a serious flaw has decreased from 0.1 to 0.01 during the developmental phase of the nuclear industry. At the same time the frequency of accidents has decreased from 0.04 per reactor year to 0.0004 per reactor year.

  19. Learning curve estimation techniques for the nuclear industry

    International Nuclear Information System (INIS)

    Vaurio, J.K.

    1983-01-01

    Statistical techniques are developed to estimate the progress made by the nuclear industry in learning to prevent accidents. Learning curves are derived for accident occurrence rates based on actuarial data, predictions are made for the future, and compact analytical equations are obtained for the statistical accuracies of the estimates. Both maximum likelihood estimation and the method of moments are applied to obtain parameters for the learning models, and results are compared to each other and to earlier graphical and analytical results. An effective statistical test is also derived to assess the significance of trends. The models used associate learning directly to accidents, to the number of plants and to the cumulative number of operating years. Using as a data base nine core damage accidents in electricity-producing plants, it is estimated that the probability of a plant to have a serious flaw has decreased from 0.1 to 0.01 during the developmental phase of the nuclear industry. At the same time the frequency of accidents has decreased from 0.04 per reactor year to 0.0004 per reactor year

  20. Learning-curve estimation techniques for nuclear industry

    International Nuclear Information System (INIS)

    Vaurio, J.K.

    1983-01-01

    Statistical techniques are developed to estimate the progress made by the nuclear industry in learning to prevent accidents. Learning curves are derived for accident occurrence rates based on acturial data, predictions are made for the future, and compact analytical equations are obtained for the statistical accuracies of the estimates. Both maximum likelihood estimation and the method of moments are applied to obtain parameters for the learning models, and results are compared to each other and to earlier graphical and analytical results. An effective statistical test is also derived to assess the significance of trends. The models used associate learning directly to accidents, to the number of plants and to the cumulative number of operating years. Using as a data base nine core damage accidents in electricity-producing plants, it is estimated that the probability of a plant to have a serious flaw has decreased from 0.1 to 0.01 during the developmental phase of the nuclear industry. At the same time the frequency of accidents has decreased from 0.04 per reactor year to 0.0004 per reactor year

  1. Transcatheter closure of patent ductus arteriosus: Evaluating the effect of the learning curve on the outcome

    Directory of Open Access Journals (Sweden)

    Azhar Ahmad

    2009-01-01

    Full Text Available Background and Objectives : Initial experience with transcatheter closure of patent ductus arteriosus (PDA using detachable coils and Amplatzer duct occluder devices is reported. We evaluated the outcome, complications, and influence of the learning curve, and also assessed the need of surgical backup for such interventional procedures. Methods: From January 2000 to December 2004, 121 patients underwent transcatheter closure of PDA. Aortic angiogram was performed to evaluate the size, position, and shape of the duct for appropriately choosing the occluder device type and size. A second aortic angiogram was performed 10 minutes after device deployment. Echocardiography was repeated at intervals of 24 hours, then at 1, 3, and 6 months after the procedure to assess complications. Stepwise multiple regression analysis was used to assess the role of experience in improving the outcome of the procedure. Results: Of 121 cases, four patients had pulmonary artery embolization of the occluder device which was successfully retrieved in the catheterization laboratory, while two others had embolization that required surgical intervention. Four patients had temporary residual leak, nine had protrusion of the device into the aorta without significant Doppler pressure gradient or hemolysis on follow-up, and five had partial hemodynamically insignificant obstruction to the left pulmonary artery. Statistical analysis showed that the effect of the learning curve and experience was responsible for 93% improvement in the procedural outcome over the five-year study period. Conclusion: Transcatheter occlusion of PDA is safe and effective alternative to surgery. Complications occurred in those with unfavorable duct anatomy and with the use of multiple coils. Surgical backup was important for such interventional procedures. Experience played a major role in the proper choice of device type and size which greatly influenced the outcome of the procedure.

  2. The learning curve of laparoscopic holecystectomy in general surgery resident training: old age of the patient may be a risk factor?

    Science.gov (United States)

    Ferrarese, Alessia; Gentile, Valentina; Bindi, Marco; Rivelli, Matteo; Cumbo, Jacopo; Solej, Mario; Enrico, Stefano; Martino, Valter

    2016-01-01

    A well-designed learning curve is essential for the acquisition of laparoscopic skills: but, are there risk factors that can derail the surgical method? From a review of the current literature on the learning curve in laparoscopic surgery, we identified learning curve components in video laparoscopic cholecystectomy; we suggest a learning curve model that can be applied to assess the progress of general surgical residents as they learn and master the stages of video laparoscopic cholecystectomy regardless of type of patient. Electronic databases were interrogated to better define the terms "surgeon", "specialized surgeon", and "specialist surgeon"; we surveyed the literature on surgical residency programs outside Italy to identify learning curve components, influential factors, the importance of tutoring, and the role of reference centers in residency education in surgery. From the definition of acceptable error, self-efficacy, and error classification, we devised a learning curve model that may be applied to training surgical residents in video laparoscopic cholecystectomy. Based on the criteria culled from the literature, the three surgeon categories (general, specialized, and specialist) are distinguished by years of experience, case volume, and error rate; the patients were distinguished for years and characteristics. The training model was constructed as a series of key learning steps in video laparoscopic cholecystectomy. Potential errors were identified and the difficulty of each step was graded using operation-specific characteristics. On completion of each procedure, error checklist scores on procedure-specific performance are tallied to track the learning curve and obtain performance indices of measurement that chart the trainee's progress. The concept of the learning curve in general surgery is disputed. The use of learning steps may enable the resident surgical trainee to acquire video laparoscopic cholecystectomy skills proportional to the instructor

  3. Assessing the impact of windfarms - the learning curve in Cornwall

    International Nuclear Information System (INIS)

    Hull, A.

    1998-01-01

    This paper uses windfarm application decisions in Cornwall between 1989 and 1995 to illustrate the learning curve of planners in assessing appropriate windfarm locations, and in particular how the process of knowledge construction is constantly reviewed and modified in the light of experience and circumstance. One of the accepted purposes of Environmental Impact Assessment is to predict the possible effects, both beneficial and adverse, of the development on the environment. In practice what is beneficial and what is adverse can be a matter of dispute. The paper draws out the role of the planning system in assessing what is problematic or benign, and the practical strategies and procedures used to assess and control the environmental impacts of wind energy schemes. (Author)

  4. e-Learning in Surgical Education: A Systematic Review.

    Science.gov (United States)

    Jayakumar, Nithish; Brunckhorst, Oliver; Dasgupta, Prokar; Khan, Muhammad Shamim; Ahmed, Kamran

    2015-01-01

    e-Learning involves the delivery of educational content through web-based methods. Owing to work-hour restrictions and changing practice patterns in surgery, e-learning can offer an effective alternative to traditional teaching. Our aims were to (1) identify current modalities of e-learning, (2) assess the efficacy of e-learning as an intervention in surgical education through a systematic review of the literature, and (3) discuss the relevance of e-learning as an educational tool in surgical education. This is the first such systematic review in this field. A systematic search of MEDLINE and EMBASE was conducted for relevant articles published until July 2014, using a predefined search strategy. The database search was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. A total of 38 articles were found which met the inclusion criteria. In these studies, e-learning was used as an intervention in 3 different ways: (1) to teach cases through virtual patients (18/38); (2) to teach theoretical knowledge through online tutorials, or other means (18/38); and (3) to teach surgical skills (2/38). Nearly all of the studies reviewed report significant knowledge gain from e-learning; however, 2 in 3 studies did not use a control group. e-Learning has emerged as an effective mode of teaching with particular relevance for surgical education today. Published studies have demonstrated the efficacy of this method; however, future work must involve well-designed randomized controlled trials comparing e-learning against standard teaching. Copyright © 2015 Association of Program Directors in Surgery. Published by Elsevier Inc. All rights reserved.

  5. Adolescent Idiopathic Scoliosis Surgery by a Neurosurgeon: Learning Curve for Neurosurgeons.

    Science.gov (United States)

    Hyun, Seung-Jae; Han, Sanghyun; Kim, Ki-Jeong; Jahng, Tae-Ahn; Kim, Yongjung J; Rhim, Seung-Chul; Kim, Hyun-Jib

    2018-02-01

    To determine a neurosurgeon's learning curve of surgical treatment for adolescent idiopathic scoliosis (AIS) patients. This study is a retrospective analysis. Forty-six patients were treated by a single neurosurgeon between 2011 and 2017 using posterior segmental instrumentation and fusion. According to the time period, the former and latter 23 patients were divided into group 1 and group 2, respectively. Patients' demographic data, curve magnitude, number of levels treated, amount of correction achieved, radiographic/clinical outcomes, and complications were compared between the groups. The majority were females (34 vs. 12) with average ages of 15.0 versus 15.6, respectively. The mean follow-up period was 24.6 months. The average number of fusion levels was similar with 10.3 and 11.5 vertebral bodies in groups 1 and 2, respectively. The average Cobb angle of major curvature was 59.8° and 58.5° in groups 1 and 2, respectively. There observed significant reductions of operative time (324.4 vs. 224.7 minutes, P = 0.007) and estimated blood loss (648.3 vs. 438.0 mL, P = 0.027) in group 2. The correction rate of the major structural curve was greater in group 2 (70.7% vs. 81.0%, P = 0.001). There was no case of neurologic deficit, infection, and revision for screw malposition. One patient of group 1 underwent fusion extension surgery for shoulder asymmetry. Radiographic and clinical outcomes of AIS patients treated by a neurosurgeon were acceptable. AIS surgery may be performed with an acceptable rate of complications after about 20 surgeries. With acquisition of surgical experiences, neurosurgeons could perform deformity surgery for AIS effectively and safely. Copyright © 2017 Elsevier Inc. All rights reserved.

  6. Evaluation of learning curves for ovariohysterectomy of dogs and cats and castration of dogs.

    Science.gov (United States)

    Freeman, Lynetta J; Ferguson, Nancy; Fellenstein, Carol; Johnson, Ron; Constable, Peter D

    2017-08-01

    OBJECTIVE To define learning curves for fourth-year veterinary students performing ovariohysterectomy procedures in dogs and cats and castration in dogs. DESIGN Retrospective study. SAMPLE 3,196 ovariohysterectomies or castrations performed in dogs and cats by 88 veterinary students during a spay-neuter surgery and animal shelter rotation (n = 3,056) or by 1 experienced general practitioner (n = 140). PROCEDURES Data collected from medical records included patient signalment, type and duration of procedure, and sequence (by date and time) of the procedure within a list of procedures of the same type generated for each student. For each procedure type, geometric mean surgery time and 95% confidence intervals were determined for each number of surgeries completed by ≥ 10 students. Median surgery times for the same procedure types were determined for the experienced practitioner. The learning curve for each procedure was modeled with nonlinear (3-factor exponential equation with a nonzero asymptote) and linear regression. For each procedure, the asymptote (optimal surgery time) for students was compared with the experienced practitioner's median surgery time. RESULTS 2,945 surgeries (mean, 33/student) performed by ≥ 10 students were analyzed. Surgery time decreased in a nonlinear manner as student experience increased for castration of adult or pediatric dogs and ovariohysterectomy of pediatric dogs and adult or pediatric cats. Surgery time decreased in a linear manner as experience increased for ovariohysterectomy of adult dogs. CONCLUSIONS AND CLINICAL RELEVANCE To the authors' knowledge, this was the first study to map surgery times for common surgical procedures consecutively performed by veterinary students. Results clearly indicated the value of repetition to improve surgical skills (as measured by surgery time) during a 3-week period.

  7. [Individual learning curve for radical robot-assisted prostatectomy based on the example of three professionals working in one clinic].

    Science.gov (United States)

    Rasner, P I; Pushkar', D Iu; Kolontarev, K B; Kotenkov, D V

    2014-01-01

    The appearance of new surgical technique always requires evaluation of its effectiveness and ease of acquisition. A comparative study of the results of the first three series of successive robot-assisted radical prostatectomy (RARP) performed on at time by three surgeons, was conducted. The series consisted of 40 procedures, and were divided into 4 groups of 10 operations for the analysis. When comparing data, statistically significant improvement of intra- and postoperative performance in each series was revealed, with increase in the number of operations performed, and in each subsequent series compared with the preceding one. We recommend to perform the planned conversion at the first operation. In our study, previous laparoscopic experience did not provide any significant advantages in the acquisition of robot-assisted technology. To characterize the individual learning curve, we recommend the use of the number of operations that the surgeon looked in the life-surgery regimen and/or in which he participated as an assistant before his own surgical activity, as well as the indicator "technical defect". In addition to the term "individual learning curve", we propose to introduce the terms "surgeon's individual training phase", and "clinic's learning curve".

  8. Developments in Interpreting Learning Curves and Applications to Energy Technology Policy

    International Nuclear Information System (INIS)

    Van der Zwaan, B.C.C.; Wene, C.O.

    2011-01-01

    The book 'Learning Curves: Theory, Models, and Applications' first draws a learning map that shows where learning is involved within organizations, then examines how it can be sustained, perfected, and accelerated. The book reviews empirical findings in the literature in terms of different sources for learning and partial assessments of the steps that make up the actual learning process inside the learning curve. Chapter 23 on 'Developments in Interpreting Learning Curves and Applications to Energy Technology Policy' is written by Bob van der Zwaan and Clas-Otto Wene. In this chapter they provide some interpretations of experience and learning curves starting from three different theoretical platforms. These interpretations are aimed at explaining learning rates for different energy technologies. The ultimate purpose is to find the role that experience and learning curves can legitimately play in designing efficient government deployment programs and in analyzing the implications of different energy scenarios. The 'Component Learning' section summarizes recent work by the authors that focuses on the disaggregation of technologies in their respective components and argues that traditional learning for overall technology should perhaps be replaced by a phenomenology that recognizes learning for individual components. The 'Learning and Time' section presents an approach that departs more strongly from the conventional learning curve methodology, by suggesting that exponential growth and progress may be the deeper underlying processes behind observed learning-by-doing. Contrary to this view, the cybernetic approach presented in the 'Cybernetic Approach' section sees learning curves as expressing a fundamental property of organizations in competitive markets and applies the findings from second order cybernetics to calculate the learning rates for operationally closed systems. All three interpretations find empirical support. The 'Conclusions' section summarizes the

  9. Developments in Interpreting Learning Curves and Applications to Energy Technology Policy

    Energy Technology Data Exchange (ETDEWEB)

    Van der Zwaan, B.C.C. [Energy research Centre of the Netherlands, ECN Policy Studies, Petten (Netherlands); Wene, C.O. [Wenergy, Lund (Sweden)

    2011-06-15

    The book 'Learning Curves: Theory, Models, and Applications' first draws a learning map that shows where learning is involved within organizations, then examines how it can be sustained, perfected, and accelerated. The book reviews empirical findings in the literature in terms of different sources for learning and partial assessments of the steps that make up the actual learning process inside the learning curve. Chapter 23 on 'Developments in Interpreting Learning Curves and Applications to Energy Technology Policy' is written by Bob van der Zwaan and Clas-Otto Wene. In this chapter they provide some interpretations of experience and learning curves starting from three different theoretical platforms. These interpretations are aimed at explaining learning rates for different energy technologies. The ultimate purpose is to find the role that experience and learning curves can legitimately play in designing efficient government deployment programs and in analyzing the implications of different energy scenarios. The 'Component Learning' section summarizes recent work by the authors that focuses on the disaggregation of technologies in their respective components and argues that traditional learning for overall technology should perhaps be replaced by a phenomenology that recognizes learning for individual components. The 'Learning and Time' section presents an approach that departs more strongly from the conventional learning curve methodology, by suggesting that exponential growth and progress may be the deeper underlying processes behind observed learning-by-doing. Contrary to this view, the cybernetic approach presented in the 'Cybernetic Approach' section sees learning curves as expressing a fundamental property of organizations in competitive markets and applies the findings from second order cybernetics to calculate the learning rates for operationally closed systems. All three interpretations find empirical

  10. Retention of fundamental surgical skills learned in robot-assisted surgery.

    Science.gov (United States)

    Suh, Irene H; Mukherjee, Mukul; Shah, Bhavin C; Oleynikov, Dmitry; Siu, Ka-Chun

    2012-12-01

    Evaluation of the learning curve for robotic surgery has shown reduced errors and decreased task completion and training times compared with regular laparoscopic surgery. However, most training evaluations of robotic surgery have only addressed short-term retention after the completion of training. Our goal was to investigate the amount of surgical skills retained after 3 months of training with the da Vinci™ Surgical System. Seven medical students without any surgical experience were recruited. Participants were trained with a 4-day training program of robotic surgical skills and underwent a series of retention tests at 1 day, 1 week, 1 month, and 3 months post-training. Data analysis included time to task completion, speed, distance traveled, and movement curvature by the instrument tip. Performance of the participants was graded using the modified Objective Structured Assessment of Technical Skills (OSATS) for robotic surgery. Participants filled out a survey after each training session by answering a set of questions. Time to task completion and the movement curvature was decreased from pre- to post-training and the performance was retained at all the corresponding retention periods: 1 day, 1 week, 1 month, and 3 months. The modified OSATS showed improvement from pre-test to post-test and this improvement was maintained during all the retention periods. Participants increased in self-confidence and mastery in performing robotic surgical tasks after training. Our novel comprehensive training program improved robot-assisted surgical performance and learning. All trainees retained their fundamental surgical skills for 3 months after receiving the training program.

  11. Surgical resident learning styles have changed with work hours.

    Science.gov (United States)

    Quillin, Ralph C; Cortez, Alexander R; Pritts, Timothy A; Hanseman, Dennis J; Edwards, Michael J; Davis, Bradley R

    2016-01-01

    The Accreditation Council for Graduate Medical Education instituted the 80-h workweek for residency programs in 2003. This presented a unique challenge for surgery residents who must acquire a medical and technical knowledge base during training. Therefore, learning should be delivered in an environment congruent with an individual's learning style. In this study, we evaluated the learning styles of general surgery residents to determine how learning styles changed after the implementation to the 80-h workweek. Kolb learning style inventory was taken by general surgery residents at the University of Cincinnati's Department of Surgery, and results from 1999-2012 were analyzed. Statistical analysis was performed using the chi-squared, logistic regression and Wilcoxon rank-sum test. Significance was defined as a P value of learning styles after the institution of the 80-h workweek to converging (43.9%) and accommodating (40.4%, P learning. This change paralleled the transition to a more team-based approach to patient care with the implementation of the 80-h workweek. These findings are important for surgical educators to consider in the development of surgical resident curriculum. Copyright © 2016 Elsevier Inc. All rights reserved.

  12. Learning curves of basic laparoscopic psychomotor skills in SINERGIA VR simulator.

    Science.gov (United States)

    Sánchez-Peralta, L F; Sánchez-Margallo, F M; Moyano-Cuevas, J L; Pagador, J B; Enciso, S; Gómez-Aguilera, E J; Usón-Gargallo, J

    2012-11-01

    Surgical simulators are currently essential within any laparoscopic training program because they provide a low-stakes, reproducible and reliable environment to acquire basic skills. The purpose of this study is to determine the training learning curve based on different metrics corresponding to five tasks included in SINERGIA laparoscopic virtual reality simulator. Thirty medical students without surgical experience participated in the study. Five tasks of SINERGIA were included: Coordination, Navigation, Navigation and touch, Accurate grasping and Coordinated pulling. Each participant was trained in SINERGIA. This training consisted of eight sessions (R1-R8) of the five mentioned tasks and was carried out in two consecutive days with four sessions per day. A statistical analysis was made, and the results of R1, R4 and R8 were pair-wise compared with Wilcoxon signed-rank test. Significance is considered at P value psychomotor skills that can be trained in SINERGIA. Therefore, and based on these results together with previous works, SINERGIA could be used as training tool with a properly designed training program.

  13. Teaching Learning Curves in an Undergraduate Economics or Operations Management Course

    Science.gov (United States)

    Naidu, Jaideep T.; Sanford, John F.

    2012-01-01

    Learning Curves has its roots in economics and behavioral psychology. Learning Curves theory has several business applications and is widely used in the industry. As faculty of Operations Management courses, we cover this topic in some depth in the classroom. In this paper, we present some of our teaching methods and material that have helped us…

  14. Preoperative learning goals set by surgical residents and faculty.

    Science.gov (United States)

    Pernar, Luise I M; Breen, Elizabeth; Ashley, Stanley W; Peyre, Sarah E

    2011-09-01

    The operating room (OR) remains the main teaching venue for surgical trainees. The OR is considered a pure-discovery learning environment; the downsides of this can be putatively overcome when faculty and trainee arrive at a shared understanding of learning. This study aimed to better understand preoperative learning goals to identify areas of commonalities and potential barrier to intraoperative teaching. Brief, structured preoperative interviews were conducted outside the OR with the resident and faculty member who were scheduled to operate together. Answers were analyzed and grouped using grounded theory. Twenty-seven resident-faculty pairs were interviewed. Nine residents (33.3%) were junior (PGY 1 and 2) and 18 (66.7%) were senior (PGY 3 through 5). Learning goal categories that emerged from the response analysis were anatomy, basic and advanced surgical skills, general and specific procedural tasks, technical autonomy, and pre-, intra-, and postoperative considerations. Residents articulated fewer learning goals than faculty (1.5 versus 2.4; P = 0.024). The most frequently identified learning goal by both groups was one classifiable under general procedural tasks; the greatest divergence was seen regarding perioperative considerations, which were identified frequently by faculty members but rarely by residents. Faculty articulate significantly more learning goals for the residents they will operate with than residents articulate for themselves. Our data suggest that residents and faculty align on some learning goals for the OR but residents tend to be more limited, focusing predominantly on technical aspects of the operation. Faculty members tend to hold a broader view of the learning potential of the OR. These discrepancies may present barriers to effective intraoperative teaching. Copyright © 2011 Elsevier Inc. All rights reserved.

  15. Rapid learning curve assessment in an ex vivo training system for microincisional glaucoma surgery.

    Science.gov (United States)

    Dang, Yalong; Waxman, Susannah; Wang, Chao; Parikh, Hardik A; Bussel, Igor I; Loewen, Ralitsa T; Xia, Xiaobo; Lathrop, Kira L; Bilonick, Richard A; Loewen, Nils A

    2017-05-09

    Increasing prevalence and cost of glaucoma have increased the demand for surgeons well trained in newer, microincisional surgery. These procedures occur in a highly confined space, making them difficult to learn by observation or assistance alone as is currently done. We hypothesized that our ex vivo outflow model is sensitive enough to allow computing individual learning curves to quantify progress and refine techniques. Seven trainees performed nine trabectome-mediated ab interno trabeculectomies in pig eyes (n = 63). An expert surgeon rated the procedure using an Operating Room Score (ORS). The extent of outflow beds accessed was measured with canalograms. Data was fitted using mixed effect models. ORS reached a half-maximum on an asymptote after only 2.5 eyes. Surgical time decreased by 1.4 minutes per eye in a linear fashion. The ablation arc followed an asymptotic function with a half-maximum inflection point after 5.3 eyes. Canalograms revealed that this progress did not correlate well with improvement in outflow, suggesting instead that about 30 eyes are needed for true mastery. This inexpensive pig eye model provides a safe and effective microsurgical training model and allows objective quantification of outcomes for the first time.

  16. A Literature-Based Analysis of the Learning Curves of Laparoscopic Radical Prostatectomy

    Directory of Open Access Journals (Sweden)

    Daniel W. Good

    2014-05-01

    Full Text Available There is a trend for the increased adoption of minimally invasive techniques of radical prostatectomy (RP – laparoscopic (LRP and robotic assisted (RARP – from the traditional open radical retropubic prostatectomy (ORP, popularised by Partin et al. Recently there has been a dramatic expansion in the rates of RARP being performed, and there have been many early reports postulating that the learning curve for RARP is shorter than for LRP. The aim of this study was to review the literature and analyse the length of the LRP learning curves for the various outcome measures: perioperative, oncologic, and functional outcomes. A broad search of the literature was performed in November 2013 using the PubMed database. Only studies of real patients and those from 2004 until 2013 were included; those on simulators were excluded. In total, 239 studies were identified after which 13 were included. The learning curve is a heterogeneous entity, depending entirely on the criteria used to define it. There is evidence of multiple learning curves; however the length of these is dependent on the definitions used by the authors. Few studies use the more rigorous definition of plateauing of the curve. Perioperative learning curve takes approximately 150-200 cases to plateau, oncologic curve approximately 200 cases, and the functional learning curve up to 700 cases to plateau (700 for potency, 200 cases for continence. In this review, we have analysed the literature with respect to the learning curve for LRP. It is clear that the learning curve is long. This necessitates centralising LRP to high volume centres such that surgeons, trainees, and patients are able to utilise the benefits of LRP.

  17. A Primer on the Statistical Modelling of Learning Curves in Health Professions Education

    Science.gov (United States)

    Pusic, Martin V.; Boutis, Kathy; Pecaric, Martin R.; Savenkov, Oleksander; Beckstead, Jason W.; Jaber, Mohamad Y.

    2017-01-01

    Learning curves are a useful way of representing the rate of learning over time. Features include an index of baseline performance (y-intercept), the efficiency of learning over time (slope parameter) and the maximal theoretical performance achievable (upper asymptote). Each of these parameters can be statistically modelled on an individual and…

  18. Femtosecond laser-assisted cataract surgery with bimanual technique: learning curve for an experienced cataract surgeon.

    Science.gov (United States)

    Cavallini, Gian Maria; Verdina, Tommaso; De Maria, Michele; Fornasari, Elisa; Volpini, Elisa; Campi, Luca

    2017-11-29

    To describe the intraoperative complications and the learning curve of microincision cataract surgery assisted by femtosecond laser (FLACS) with bimanual technique performed by an experienced surgeon. It is a prospective, observational, comparative case series. A total of 120 eyes which underwent bimanual FLACS by the same experienced surgeon during his first experience were included in the study; we considered the first 60 cases as Group A and the second 60 cases as Group B. In both groups, only nuclear sclerosis of grade 2 or 3 was included; an intraocular lens was implanted through a 1.4-mm incision. Best-corrected visual acuity (BCVA), surgically induced astigmatism (SIA), central corneal thickness and endothelial cell loss (ECL) were evaluated before and at 1 and 3 months after surgery. Intraoperative parameters, and intra- and post-operative complications were recorded. In Group A, we had femtosecond laser-related minor complications in 11 cases (18.3%) and post-operative complications in 2 cases (3.3%); in Group B, we recorded 2 cases (3.3%) of femtosecond laser-related minor complications with no post-operative complications. Mean effective phaco time (EPT) was 5.32 ± 3.68 s in Group A and 4.34 ± 2.39 s in Group B with a significant difference (p = 0.046). We recorded a significant mean BCVA improvement at 3 months in both groups (p  0.05). Finally, we found significant ECL in both groups with a significant difference between the two groups (p = 0.042). FLACS with bimanual technique and low-energy LDV Z8 is associated with a necessary initial learning curve. After the first adjustments in the surgical technique, this technology seems to be safe and effective with rapid visual recovery and it helps surgeons to standardize the crucial steps of cataract surgery.

  19. Retrospective analysis of the learning curve associated with laparoscopic ovariectomy in dogs and associated perioperative complication rates.

    Science.gov (United States)

    Pope, Juliet Frances Anne; Knowles, Toby Grahame

    2014-08-01

    To assess the learning curve associated with laparoscopic ovariectomy (LOE) in 618 dogs and to report perioperative complication rates. Case series. Dogs (n = 618). Data retrieved from the medical records of bitches admitted for LOE over 42 months included date of surgery, breed, weight (kg), age (months), surgeon, suture material used, intraoperative complications and postoperative complications. Each LOE was defined as "successful" or "unsuccessful" by the absence or presence of an intraoperative complication and "failure" rate described using a CUSUM technique. Follow-up time ranged from 152 to 1,435 days (median, 737 days). Intraoperative complications occurred in 10 dogs (1.6%) and included: splenic laceration (6 dogs; 1%), urinary bladder perforation (3 dogs; 0.5%), and subcutaneous emphysema (1 dog; 0.2%). Postoperative complications occurred in 99 dogs (16%) and included: incisional inflammation treated with antibiotics (87 dogs [14%]; 96/1,854 incisions; 5.1%), incisional seroma (5 dogs [0.8%]; 5/1,854 incisions, 0.3%), incisional hernia (4 dogs [0.6%]; 4/1,854 incisions, 0.2%), and ovarian remnant syndrome (3 dogs; 0.5%). CUSUM charts indicated an initial "learning curve" of ∼80 LOE. LOE is a technique with an initial learning curve but once surgical proficiency is reached after ∼80 procedures then intraoperative complication rates associated with the procedure can be low. © Copyright 2014 by The American College of Veterinary Surgeons.

  20. Unraveling the photovoltaic technology learning curve by incorporation of input price changes and scale effects

    International Nuclear Information System (INIS)

    Yu, C.F.; van Sark, W.G.J.H.M.; Alsema, E.A.

    2011-01-01

    In a large number of energy models, the use of learning curves for estimating technological improvements has become popular. This is based on the assumption that technological development can be monitored by following cost development as a function of market size. However, recent data show that in some stages of photovoltaic technology (PV) production, the market price of PV modules stabilizes even though the cumulative capacity increases. This implies that no technological improvement takes place in these periods: the cost predicted by the learning curve in the PV study is lower than the market one. We propose that this bias results from ignoring the effects of input prices and scale effects, and that incorporating the input prices and scale effects into the learning curve theory is an important issue in making cost predictions more reliable. In this paper, a methodology is described to incorporate the scale and input-prices effect as the additional variables into the one factor learning curve, which leads to the definition of the multi-factor learning curve. This multi-factor learning curve is not only derived from economic theories, but also supported by an empirical study. The results clearly show that input prices and scale effects are to be included, and that, although market prices are stabilizing, learning is still taking place. (author)

  1. Learner Characteristic Based Learning Effort Curve Mode: The Core Mechanism on Developing Personalized Adaptive E-Learning Platform

    Science.gov (United States)

    Hsu, Pi-Shan

    2012-01-01

    This study aims to develop the core mechanism for realizing the development of personalized adaptive e-learning platform, which is based on the previous learning effort curve research and takes into account the learner characteristics of learning style and self-efficacy. 125 university students from Taiwan are classified into 16 groups according…

  2. Learning curves for ultrasound guided lung biopsy in the hands of respiratory physicians

    DEFF Research Database (Denmark)

    Laursen, Christian; Naur, Therese Maria Henriette; Bodtger, Uffe

    2016-01-01

    are depicted in figure 1. Six of the physicians had learning curves with a relatively downward or stable projection as a sign of developing competence. Three physicians, however, had learning curves with an upward projection indicating unacceptable competence in performing the procedure......Background: The aim of this study was to determine learning curves for ultrasound guided transthoracic needle biopsies (US-TTNB) performed by respiratory physicians after implementation at three different centers.Methods: During January 2012 to August 2014 patients were included if they had...... a registered US-TTNB procedure at any of the three centers. The US-TTNB was defined as being successful if the result was diagnostic and otherwise as being unsuccessful. Histology or cytology results and clinical follow-up were used as a reference tests. The learning curves for physicians having performed...

  3. Learning curve for laparoendoscopic single-site surgery for an experienced laparoscopic surgeon

    Directory of Open Access Journals (Sweden)

    Pao-Ling Torng

    2013-11-01

    Conclusion: LESS is a safe and feasible alternative to conventional laparoscopic surgery for adnexal and uterine diseases. A learning curve is not required for LESS surgery for experienced laparoscopic surgeons.

  4. Surgical treatment of adult scoliosis: is anterior apical release and fusion necessary for the lumbar curve?

    Science.gov (United States)

    Kim, Youngbae B; Lenke, Lawrence G; Kim, Yongjung J; Kim, Young-Woo; Bridwell, Keith H; Stobbs, Georgia

    2008-05-01

    A retrospective study. To analyze radiographic and functional outcomes after posterior segmental spinal instrumentation and fusion (PSSIF) with and without an anterior apical release of the lumbar curve in adult scoliosis patients. No comparison study on PSSIF of adult lumbar scoliosis with apical release versus without has been published. Forty-eight adult patients with lumbar scoliosis (average age at surgery 49.6 years, average follow-up 3.7 years) who underwent PSSIF were analyzed with respect to radiographic change, perioperative and postoperative complications, and Scoliosis Research Society (SRS) outcome scores. Twenty-three patients underwent an anterior apical release of the lumbar curve via a thoracoabdominal approach followed by PSSIF (Group I). The remaining 25 patients underwent a PSSIF of the lumbar curve followed by anterior column support at the lumbosacral region through an anterior paramedian retroperitoneal or posterior transforaminal approach (Group II). Before surgery, Group I showed a somewhat larger lumbar major Cobb angle (63.2 degrees vs. 55.9 degrees , P = 0.07), and both groups demonstrated significant differences in lumbar curve flexibility (26.9% vs. 37.2%, P = 0.02) and thoracolumbar kyphosis (27.0 degrees vs. 15.0 degrees , P = 0.03). After surgery, at the ultimate follow-up, there were no significant differences in major Cobb angle, C7 plumbline to the center sacral vertical line (P = 0.17), C7 plumbline to the posterior superior endplate of S1 (P = 0.44), and sagittal Cobb angles at the proximal junction (P = 0.57), T10-L2 (P = 0.24) and T12-S1 (P = 0.51). There were 4 pseudarthroses in Group I and one in Group II (P = 0.02). Postoperative total normalized SRS outcome scores at ultimate follow-up were significantly higher in Group II (69% vs. 79%, P = 0.01). Posterior segmental spinal instrumentation and fusion without anterior apical release of lumbar curves in adult scoliosis demonstrated better total SRS outcome scores and no

  5. The Predictive Value of Ultrasound Learning Curves Across Simulated and Clinical Settings

    DEFF Research Database (Denmark)

    Madsen, Mette E; Nørgaard, Lone N; Tabor, Ann

    2017-01-01

    OBJECTIVES: The aim of the study was to explore whether learning curves on a virtual-reality (VR) sonographic simulator can be used to predict subsequent learning curves on a physical mannequin and learning curves during clinical training. METHODS: Twenty midwives completed a simulation-based tra......OBJECTIVES: The aim of the study was to explore whether learning curves on a virtual-reality (VR) sonographic simulator can be used to predict subsequent learning curves on a physical mannequin and learning curves during clinical training. METHODS: Twenty midwives completed a simulation......-based training program in transvaginal sonography. The training was conducted on a VR simulator as well as on a physical mannequin. A subgroup of 6 participants underwent subsequent clinical training. During each of the 3 steps, the participants' performance was assessed using instruments with established...... settings. RESULTS: A good correlation was found between time needed to achieve predefined performance levels on the VR simulator and the physical mannequin (Pearson correlation coefficient .78; P VR simulator correlated well to the clinical performance scores (Pearson...

  6. [E-learning in surgical procedure manuals and blogs].

    Science.gov (United States)

    Pape-Köhler, C; Chmelik, C; Heiss, M M; Jauch, K W

    2010-01-01

    E-learning is the constant companion for every surgeon in the initial years of training. Later they will be mostly used as reliable reference works. With the spread of computers and the possibilities of the World Wide Web there is an increasingly large selection of electronic learning options on the market. In this review the most important current surgical e-learning options will be presented. Inclusion criteria were determined according to a defined term which must be fulfilled for e-learning in operation techniques. Options were identified by an online search and analyzed using a criteria catalogue. This catalogue contained a total of 31 criteria for the fields of "content presentation", "infrastructure" and "evaluation". A differentiation was made between online and offline options. A total of five online and five offline options which fulfilled the inclusion criteria could be identified. None of the options currently encompass a similarly high number of operations compared to those offered in conventional operation textbooks. The use and combination of media, such as video and animation, are limited to online options and are available in various forms and combinations. The use of options is mostly free of charge and at most registration is necessary. Some of the options are multilingual. The range of e-learning options for general and visceral surgical operations is at present still limited and reduced to a few platforms. The scientific content and validity of the contents are not always guaranteed. It remains to be seen how the options presented here will develop further and what the results of the necessary scientific evaluation will be.

  7. Cognitive learning during surgical residency. A model for curriculum evaluation.

    Science.gov (United States)

    Rhodes, R S; Wile, M Z; Persons, M L; Shuck, J M

    1987-02-01

    The program summary of the American Board of Surgery In-Service Training Exam (ABSITE) can be used to quantitate cognitive learning during a surgical residency and to identify areas of curricular weakness in a residency program. Knowledge on each question is categorized as high (known) or low (unknown) depending on the percentage of residents who answered correctly. Knowledge of Level 1 (entry) residents is then compared with Level 5 (exit) residents. Each ABSITE question can thus be categorized on entry versus exit as known-known, unknown-unknown, unknown-known, and known-unknown. Only about half of unknown knowledge on entry appears to become known on exit. Very little knowledge known on entry becomes unknown on exit. Weaknesses in specific subject areas can be readily identified by ranking questions according to the number of exiting residents who answer incorrectly. Use of this technique to quantitate cognitive learning in a residency program may allow objective assessment of changes in curriculum.

  8. Effective e-learning in surgical education: the core values underpinning effective e-learning environments and how these may be enhanced for future surgical education.

    Science.gov (United States)

    Bamford, R; Coulston, J

    2016-01-01

    e-learning is a valuable tool that has a number of advantages for Surgical Oncology training and education. The rapidly evolving nature of, and limited clinical exposure to oncological practice creates challenges for surgical trainees to stay up to date and engaged. Online learning can be accessed anywhere at any time and allows trainees to develop, apply and be assessed on their learning. To be effective, it must be educationally sound and embrace technology to enhance learners' experience.

  9. Laparoscopy Instructional Videos : The Effect of Preoperative Compared With Intraoperative Use on Learning Curves

    NARCIS (Netherlands)

    Broekema, Theo H.; Talsma, Aaldert K.; Wevers, Kevin P.; Pierie, Jean-Pierre E. N.

    OBJECTIVE: Previous studies have shown that the use of intraoperative instructional videos has a positive effect on learning laparoscopic procedures. This study investigated the effect of the timing of the instructional videos on learning curves in laparoscopic skills training. DESIGN: After

  10. Learning Curves and Bootstrap Estimates for Inference with Gaussian Processes: A Statistical Mechanics Study

    DEFF Research Database (Denmark)

    Malzahn, Dorthe; Opper, Manfred

    2003-01-01

    We employ the replica method of statistical physics to study the average case performance of learning systems. The new feature of our theory is that general distributions of data can be treated, which enables applications to real data. For a class of Bayesian prediction models which are based...... on Gaussian processes, we discuss Bootstrap estimates for learning curves....

  11. The learning curve associated with the introduction of the subcutaneous implantable defibrillator

    NARCIS (Netherlands)

    Knops, Reinoud E.; Brouwer, Tom F.; Barr, Craig S.; Theuns, Dominic A.; Boersma, Lucas; Weiss, Raul; Neuzil, Petr; Scholten, Marcoen; Lambiase, Pier D.; Leon, Angel R.; Hood, Margaret; Jones, Paul W.; Wold, Nicholas; Grace, Andrew A.; Olde Nordkamp, Louise R. A.; Burke, Martin C.

    2016-01-01

    Aims The subcutaneous implantable cardioverter defibrillator (S-ICD) was introduced to overcome complications related to transvenous leads. Adoption of the S-ICD requires implanters to learn a new implantation technique. The aim of this study was to assess the learning curve for S-ICD implanters

  12. The learning curve associated with the introduction of the subcutaneous implantable defibrillator

    NARCIS (Netherlands)

    R.E. Knops (Reinoud); T.F. Brouwer (Tom F.); C.S. Barr (Craig); D.A.M.J. Theuns (Dominic); L. Boersma (Lucas); R. Weiss (Ram); P. Neuzil (Petr); M.F. Scholten (Marcoen); P.D. Lambiase (Pier); A. Leon (Angel); A.M. Hood (Margaret); P. Jones; Wold, N. (Nicholas); Grace, A.A. (Andrew A.); L.R.A. Olde Nordkamp (Louise R.A.); M.C. Burke (Martin)

    2016-01-01

    textabstractAims: The subcutaneous implantable cardioverter defibrillator (S-ICD) was introduced to overcome complications related to transvenous leads. Adoption of the S-ICD requires implanters to learn a new implantation technique. The aim of this study was to assess the learning curve for S-ICD

  13. Improving Accuracy and Temporal Resolution of Learning Curve Estimation for within- and across-Session Analysis

    Science.gov (United States)

    Tabelow, Karsten; König, Reinhard; Polzehl, Jörg

    2016-01-01

    Estimation of learning curves is ubiquitously based on proportions of correct responses within moving trial windows. Thereby, it is tacitly assumed that learning performance is constant within the moving windows, which, however, is often not the case. In the present study we demonstrate that violations of this assumption lead to systematic errors in the analysis of learning curves, and we explored the dependency of these errors on window size, different statistical models, and learning phase. To reduce these errors in the analysis of single-subject data as well as on the population level, we propose adequate statistical methods for the estimation of learning curves and the construction of confidence intervals, trial by trial. Applied to data from an avoidance learning experiment with rodents, these methods revealed performance changes occurring at multiple time scales within and across training sessions which were otherwise obscured in the conventional analysis. Our work shows that the proper assessment of the behavioral dynamics of learning at high temporal resolution can shed new light on specific learning processes, and, thus, allows to refine existing learning concepts. It further disambiguates the interpretation of neurophysiological signal changes recorded during training in relation to learning. PMID:27303809

  14. Improving Accuracy and Temporal Resolution of Learning Curve Estimation for within- and across-Session Analysis.

    Directory of Open Access Journals (Sweden)

    Matthias Deliano

    Full Text Available Estimation of learning curves is ubiquitously based on proportions of correct responses within moving trial windows. Thereby, it is tacitly assumed that learning performance is constant within the moving windows, which, however, is often not the case. In the present study we demonstrate that violations of this assumption lead to systematic errors in the analysis of learning curves, and we explored the dependency of these errors on window size, different statistical models, and learning phase. To reduce these errors in the analysis of single-subject data as well as on the population level, we propose adequate statistical methods for the estimation of learning curves and the construction of confidence intervals, trial by trial. Applied to data from an avoidance learning experiment with rodents, these methods revealed performance changes occurring at multiple time scales within and across training sessions which were otherwise obscured in the conventional analysis. Our work shows that the proper assessment of the behavioral dynamics of learning at high temporal resolution can shed new light on specific learning processes, and, thus, allows to refine existing learning concepts. It further disambiguates the interpretation of neurophysiological signal changes recorded during training in relation to learning.

  15. Can Online Learning Bend the Higher Education Cost Curve?

    OpenAIRE

    David J. Deming; Claudia Goldin; Lawrence F. Katz; Noam Yuchtman

    2015-01-01

    We examine whether online learning technologies have led to lower prices in higher education. Using data from the Integrated Postsecondary Education Data System, we show that online education is concentrated in large for-profit chains and less-selective public institutions. We find that colleges with a higher share of online students charge lower tuition prices. We present evidence of declining real and relative prices for full-time undergraduate online education from 2006 to 2013. Although t...

  16. Hysteroscopic sterilization using a virtual reality simulator: assessment of learning curve.

    Science.gov (United States)

    Janse, Juliënne A; Goedegebuure, Ruben S A; Veersema, Sebastiaan; Broekmans, Frank J M; Schreuder, Henk W R

    2013-01-01

    To assess the learning curve using a virtual reality simulator for hysteroscopic sterilization with the Essure method. Prospective multicenter study (Canadian Task Force classification II-2). University and teaching hospital in the Netherlands. Thirty novices (medical students) and five experts (gynecologists who had performed >150 Essure sterilization procedures). All participants performed nine repetitions of bilateral Essure placement on the simulator. Novices returned after 2 weeks and performed a second series of five repetitions to assess retention of skills. Structured observations on performance using the Global Rating Scale and parameters derived from the simulator provided measurements for analysis. The learning curve is represented by improvement per procedure. Two-way repeated-measures analysis of variance was used to analyze learning curves. Effect size (ES) was calculated to express the practical significance of the results (ES ≥ 0.50 indicates a large learning effect). For all parameters, significant improvements were found in novice performance within nine repetitions. Large learning effects were established for six of eight parameters (p learning curve established in this study endorses future implementation of the simulator in curricula on hysteroscopic skill acquisition for clinicians who are interested in learning this sterilization technique. Copyright © 2013 AAGL. Published by Elsevier Inc. All rights reserved.

  17. Simultaneous development of laparoscopy and robotics provides acceptable perioperative outcomes and shows robotics to have a faster learning curve and to be overall faster in rectal cancer surgery: analysis of novice MIS surgeon learning curves.

    Science.gov (United States)

    Melich, George; Hong, Young Ki; Kim, Jieun; Hur, Hyuk; Baik, Seung Hyuk; Kim, Nam Kyu; Sender Liberman, A; Min, Byung Soh

    2015-03-01

    Laparoscopy offers some evidence of benefit compared to open rectal surgery. Robotic rectal surgery is evolving into an accepted approach. The objective was to analyze and compare laparoscopic and robotic rectal surgery learning curves with respect to operative times and perioperative outcomes for a novice minimally invasive colorectal surgeon. One hundred and six laparoscopic and 92 robotic LAR rectal surgery cases were analyzed. All surgeries were performed by a surgeon who was primarily trained in open rectal surgery. Patient characteristics and perioperative outcomes were analyzed. Operative time and CUSUM plots were used for evaluating the learning curve for laparoscopic versus robotic LAR. Laparoscopic versus robotic LAR outcomes feature initial group operative times of 308 (291-325) min versus 397 (373-420) min and last group times of 220 (212-229) min versus 204 (196-211) min-reversed in favor of robotics; major complications of 4.7 versus 6.5 % (NS), resection margin involvement of 2.8 versus 4.4 % (NS), conversion rate of 3.8 versus 1.1 (NS), lymph node harvest of 16.3 versus 17.2 (NS), and estimated blood loss of 231 versus 201 cc (NS). Due to faster learning curves for extracorporeal phase and total mesorectal excision phase, the robotic surgery was observed to be faster than laparoscopic surgery after the initial 41 cases. CUSUM plots demonstrate acceptable perioperative surgical outcomes from the beginning of the study. Initial robotic operative times improved with practice rapidly and eventually became faster than those for laparoscopy. Developing both laparoscopic and robotic skills simultaneously can provide acceptable perioperative outcomes in rectal surgery. It might be suggested that in the current milieu of clashing interests between evolving technology and economic constrains, there might be advantages in embracing both approaches.

  18. The Quantitative Evaluation of Functional Neuroimaging Experiments: Mutual Information Learning Curves

    DEFF Research Database (Denmark)

    Kjems, Ulrik; Hansen, Lars Kai; Anderson, Jon

    2002-01-01

    Learning curves are presented as an unbiased means for evaluating the performance of models for neuroimaging data analysis. The learning curve measures the predictive performance in terms of the generalization or prediction error as a function of the number of independent examples (e.g., subjects......) used to determine the parameters in the model. Cross-validation resampling is used to obtain unbiased estimates of a generic multivariate Gaussian classifier, for training set sizes from 2 to 16 subjects. We apply the framework to four different activation experiments, in this case \\$\\backslash......\\$[/sup 15/ O]water data sets, although the framework is equally valid for multisubject fMRI studies. We demonstrate how the prediction error can be expressed as the mutual information between the scan and the scan label, measured in units of bits. The mutual information learning curve can be used...

  19. Single-centre experience of retroperitoneoscopic approach in urology with tips to overcome the steep learning curve

    Directory of Open Access Journals (Sweden)

    Aneesh Srivastava

    2016-01-01

    Full Text Available Context: The retroperitoneoscopic or retroperitoneal (RP surgical approach has not become as popular as the transperitoneal (TP one due to the steeper learning curve. Aims: Our single-institution experience focuses on the feasibility, advantages and complications of retroperitoneoscopic surgeries (RS performed over the past 10 years. Tips and tricks have been discussed to overcome the steep learning curve and these are emphasised. Settings and Design: This study made a retrospective analysis of computerised hospital data of patients who underwent RP urological procedures from 2003 to 2013 at a tertiary care centre. Patients and Methods: Between 2003 and 2013, 314 cases of RS were performed for various urological procedures. We analysed the operative time, peri-operative complications, time to return of bowel sound, length of hospital stay, and advantages and difficulties involved. Post-operative complications were stratified into five grades using modified Clavien classification (MCC. Results: RS were successfully completed in 95.5% of patients, with 4% of the procedures electively performed by the combined approach (both RP and TP; 3.2% required open conversion and 1.3% were converted to the TP approach. The most common cause for conversion was bleeding. Mean hospital stay was 3.2 ± 1.2 days and the mean time for returning of bowel sounds was 16.5 ± 5.4 h. Of the patients, 1.4% required peri-operative blood transfusion. A total of 16 patients (5% had post-operative complications and the majority were grades I and II as per MCC. The rates of intra-operative and post-operative complications depended on the difficulty of the procedure, but the complications diminished over the years with the increasing experience of surgeons. Conclusion: Retroperitoneoscopy has proven an excellent approach, with certain advantages. The tips and tricks that have been provided and emphasised should definitely help to minimise the steep learning curve.

  20. Balloon dilation of the eustachian tube in a cadaver model: technical considerations, learning curve, and potential barriers.

    Science.gov (United States)

    McCoul, Edward D; Singh, Ameet; Anand, Vijay K; Tabaee, Abtin

    2012-04-01

    The surgical management options for eustachian tube dysfunction have historically been limited. The goal of the current study was to evaluate the technical considerations, learning curve, and potential barriers for balloon dilation of the eustachian tube (BDET) as an alternative treatment modality. Prospective preclinical trial of BDET in a cadaver model. A novel balloon catheter device was used for eustachian tube dilation. Twenty-four BDET procedures were performed by three independent rhinologists with no prior experience with the procedure (eight procedures per surgeon). The duration and number of attempts of the individual steps and overall procedure were recorded. Endoscopic examination of the eustachian tube was performed after each procedure, and the surgeon was asked to rate the subjective difficulty on a five-point scale. Successful completion of the procedure occurred in each case. The overall mean duration of the procedure was 284 seconds, and a mean number of 1.15 attempts were necessary to perform the individual steps. The mean subjective procedure difficulty was noted as somewhat easy. Statistically shorter duration and subjectively easier procedure were noted in the second compared to the first half of the series, indicating a favorable learning curve. Linear fissuring within the eustachian tube lumen without submucosal disruption (nine procedures, 37%) and with submucosal disruption (five procedures, 21%) were noted. The significance of these physical findings is unclear. Preclinical testing of BDET is associated with favorable duration, learning curve, and overall ease of completion. Clinical trials are necessary to evaluate safety and efficacy. Copyright © 2012 The American Laryngological, Rhinological, and Otological Society, Inc.

  1. Evaluation of the learning curve of non-penetrating glaucoma surgery.

    Science.gov (United States)

    Aslan, Fatih; Yuce, Berna; Oztas, Zafer; Ates, Halil

    2017-08-11

    To evaluate the learning curve of non-penetrating glaucoma surgery (NPGS). The study included 32 eyes of 27 patients' (20 male and 7 female) with medically uncontrolled glaucoma. Non-penetrating glaucoma surgeries performed by trainees under control of an experienced surgeon between 2005 and 2007 at our tertiary referral hospital were evaluated. Residents were separated into two groups. Humanistic training model applied to the one in the first group, he studied with experimental models before performing NPGS. Two residents in the second group performed NPGS after a conventional training model. Surgeries of the residents were recorded on video and intraoperative parameters were scored by the experienced surgeon at the end of the study. Postoperative intraocular pressure, absolute and total success rates were analyzed. In the first group 19 eyes of 16 patients and in the second group 13 eyes of 11 patients had been operated by residents. Intraoperative parameters and complication rates were not statistically significant between groups (p > 0.05, Chi-square). The duration of surgery was 32.7 ± 5.6 min in the first group and 45 ± 3.8 min in the second group. The difference was statistically significant (p < 0.001, Student's t test). Absolute and total success was 68.8 and 93.8% in the first group and 62.5 and 87.5% in the second group, respectively. The difference was not statistically significant. Humanistic and conventional training models under control of an experienced surgeon are safe and effective for senior residents who manage phacoemulsification surgery in routine cataract cases. Senior residents can practice these surgical techniques with reasonable complication rates.

  2. Impact of the learning curve on outcome after transcatheter mitral valve repair

    DEFF Research Database (Denmark)

    Ledwoch, Jakob; Franke, Jennifer; Baldus, Stephan

    2014-01-01

    AIMS: This analysis from the German Mitral Valve Registry investigates the impact of the learning curve with the MitraClip(®) technique on procedural success and complications. METHODS AND RESULTS: Consecutive patients treated since 2009 in centers that performed more than 50 transcatheter mitral...... not decrease over time. CONCLUSION: A learning curve using the MitraClip(®) device does not appear to significantly affect acute MR reduction, hospital and 30-day mortality. Most likely, the proctor system leads to already high initial procedure success and relatively short procedure time....

  3. Current Techniques of Teaching and Learning in Bariatric Surgical Procedures: A Systematic Review.

    Science.gov (United States)

    Kaijser, Mirjam; van Ramshorst, Gabrielle; van Wagensveld, Bart; Pierie, Jean-Pierre

    The gastric sleeve resection and gastric bypass are the 2 most commonly performed bariatric procedures. This article provides an overview of current teaching and learning methods of those techniques in resident and fellow training. A database search was performed on Pubmed, Embase, and the Education Resources Information Center (ERIC) to identify the methods used to provide training in bariatric surgery worldwide. After exclusion based on titles and abstracts, full texts of the selected articles were assessed. Included articles were reviewed using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) system. In total, 2442 titles were identified and 14 full text articles met inclusion criteria. Four publications described an ex vivo training course, and 6 focused on at least 1 step of the gastric bypass procedure. Two randomized controlled trials (RCT) provided high-quality evidence on training aspects. Surgical coaching caused significant improvement of Bariatric Objective Structured Assessment of Technical Skills (BOSATS) scores (3.60 vs. 3.90, p = 0.017) and reduction of technical errors (18 vs. 10, p = 0.003). A preoperative warm-up increased global rating scales (GRS) scores on depth perception (p = 0.02), bimanual dexterity (p = 0.01), and efficiency of movements (p = 0.03). Stepwise education, surgical coaching, warming up, Internet-based knowledge modules, and ex vivo training courses are effective in relation to bariatric surgical training of residents and fellows, possibly shortening their learning curves. Copyright © 2018 Association of Program Directors in Surgery. Published by Elsevier Inc. All rights reserved.

  4. SILC for SILC: Single Institution Learning Curve for Single-Incision Laparoscopic Cholecystectomy

    Directory of Open Access Journals (Sweden)

    Chee Wei Tay

    2013-01-01

    Full Text Available Objectives. We report the single-incision laparoscopic cholecystectomy (SILC learning experience of 2 hepatobiliary surgeons and the factors that could influence the learning curve of SILC. Methods. Patients who underwent SILC by Surgeons A and B were studied retrospectively. Operating time, conversion rate, reason for conversion, identity of first assistants, and their experience with previous laparoscopic cholecystectomy (LC were analysed. CUSUM analysis is used to identify learning curve. Results. Hundred and nineteen SILC cases were performed by Surgeons A and B, respectively. Eight cases required additional port. In CUSUM analysis, most conversion occurred during the first 19 cases. Operating time was significantly lower (62.5 versus 90.6 min, P = 0.04 after the learning curve has been overcome. Operating time decreases as the experience increases, especially Surgeon B. Most conversions are due to adhesion at Calot’s triangle. Acute cholecystitis, patients’ BMI, and previous surgery do not seem to influence conversion rate. Mean operating times of cases assisted by first assistant with and without LC experience were 48 and 74 minutes, respectively (P = 0.004. Conclusion. Nineteen cases are needed to overcome the learning curve of SILC. Team work, assistant with CLC experience, and appropriate equipment and technique are the important factors in performing SILC.

  5. Learning curve for robotic-assisted surgery for rectal cancer: use of the cumulative sum method.

    Science.gov (United States)

    Yamaguchi, Tomohiro; Kinugasa, Yusuke; Shiomi, Akio; Sato, Sumito; Yamakawa, Yushi; Kagawa, Hiroyasu; Tomioka, Hiroyuki; Mori, Keita

    2015-07-01

    Few data are available to assess the learning curve for robotic-assisted surgery for rectal cancer. The aim of the present study was to evaluate the learning curve for robotic-assisted surgery for rectal cancer by a surgeon at a single institute. From December 2011 to August 2013, a total of 80 consecutive patients who underwent robotic-assisted surgery for rectal cancer performed by the same surgeon were included in this study. The learning curve was analyzed using the cumulative sum method. This method was used for all 80 cases, taking into account operative time. Operative procedures included anterior resections in 6 patients, low anterior resections in 46 patients, intersphincteric resections in 22 patients, and abdominoperineal resections in 6 patients. Lateral lymph node dissection was performed in 28 patients. Median operative time was 280 min (range 135-683 min), and median blood loss was 17 mL (range 0-690 mL). No postoperative complications of Clavien-Dindo classification Grade III or IV were encountered. We arranged operative times and calculated cumulative sum values, allowing differentiation of three phases: phase I, Cases 1-25; phase II, Cases 26-50; and phase III, Cases 51-80. Our data suggested three phases of the learning curve in robotic-assisted surgery for rectal cancer. The first 25 cases formed the learning phase.

  6. Industrial Learning Curves Series Production of the LHC Main Superconduting Dipoles

    CERN Document Server

    Fessia, Paolo; Rossi, Lucio

    2007-01-01

    By mid August 2006, 1160 of the 1232 of LHC main dipoles have been delivered to CERN by the three suppliers in charge of the production. The training of the staff, mostly hired just for this manufacture, and the improvement of the procedures with the acquired experience, naturally decrease the time necessary for the assembly of a unit. The aim of this paper is to apply methodologies like the cost-based learning curves and the time-based learning curves to the LHC Main Dipole production comparing the estimated learning percentage to the ones experienced in other industries. This type of analysis, already presented on 500 units is here extended to more than 1000 completed units. The work also tries to identify which type of industry presents the learning percentages that are the most similar to our case and to investigate the impact of the production strategy on the process efficiency.

  7. An exploratory analysis of personality, attitudes, and study skills on the learning curve within a team-based learning environment.

    Science.gov (United States)

    Persky, Adam M; Henry, Teague; Campbell, Ashley

    2015-03-25

    To examine factors that determine the interindividual variability of learning within a team-based learning environment. Students in a pharmacokinetics course were given 4 interim, low-stakes cumulative assessments throughout the semester and a cumulative final examination. Students' Myers-Briggs personality type was assessed, as well as their study skills, motivations, and attitudes towards team-learning. A latent curve model (LCM) was applied and various covariates were assessed to improve the regression model. A quadratic LCM was applied for the first 4 assessments to predict final examination performance. None of the covariates examined significantly impacted the regression model fit except metacognitive self-regulation, which explained some of the variability in the rate of learning. There were some correlations between personality type and attitudes towards team learning, with introverts having a lower opinion of team-learning than extroverts. The LCM could readily describe the learning curve. Extroverted and introverted personality types had the same learning performance even though preference for team-learning was lower in introverts. Other personality traits, study skills, or practice did not significantly contribute to the learning variability in this course.

  8. Surgical education and adult learning: Integrating theory into practice [version 1; referees: 3 approved

    Directory of Open Access Journals (Sweden)

    Prem Rashid

    2017-02-01

    Full Text Available Surgical education continues to evolve from the master-apprentice model. Newer methods of the process need to be used to manage the dual challenges of educating while providing safe surgical care. This requires integrating adult learning concepts into delivery of practical training and education in busy clinical environments. A narrative review aimed at outlining and integrating adult learning and surgical education theory was undertaken. Additionally, this information was used to relate the practical delivery of surgical training and education in day-to-day surgical practice. Concepts were sourced from reference material. Additional material was found using a PubMed search of the words: ‘surgical education theory’ and ‘adult learning theory medical’. This yielded 1351 abstracts, of which 43 articles with a focus on key concepts in adult education theory were used. Key papers were used to formulate structure and additional cross-referenced papers were included where appropriate. Current concepts within adult learning have a lot to offer when considering how to better deliver surgical education and training. Better integration of adult learning theory can be fruitful. Individual teaching surgical units need to rethink their paradigms and consider how each individual can contribute to the education experience. Up skilling courses for trainers can do much to improve the delivery of surgical education. Understanding adult learning concepts and integrating these into day-to-day teaching can be valuable.

  9. Why the Kantian ideal survives medical learning curves, and why it matters.

    Science.gov (United States)

    Brecher, B

    2006-09-01

    The "Kantian ideal" is often misunderstood as invoking individual autonomy rather than rational self legislation. Le Morvan and Stock's otherwise insightful discussion of "Medical learning curves and the Kantian ideal"--for example--draws the mistaken inference that that ideal is inconsistent with the realities of medical practice. But it is not. Rationally to be a patient entails accepting its necessary conditions.

  10. Total hip arthroplasty by the direct anterior approach using a neck-preserving stem: Safety, efficacy and learning curve

    Directory of Open Access Journals (Sweden)

    Aditya Khemka

    2018-01-01

    functional outcomes but with a learning curve for the surgical technique, implants sizing, and the risk of intraoperative neck fractures.

  11. The learning effect of intraoperative video-enhanced surgical procedure training.

    Science.gov (United States)

    van Det, M J; Meijerink, W J H J; Hoff, C; Middel, L J; Koopal, S A; Pierie, J P E N

    2011-07-01

    The transition from basic skills training in a skills lab to procedure training in the operating theater using the traditional master-apprentice model (MAM) lacks uniformity and efficiency. When the supervising surgeon performs parts of a procedure, training opportunities are lost. To minimize this intervention by the supervisor and maximize the actual operating time for the trainee, we created a new training method called INtraoperative Video-Enhanced Surgical Training (INVEST). Ten surgical residents were trained in laparoscopic cholecystectomy either by the MAM or with INVEST. Each trainee performed six cholecystectomies that were objectively evaluated on an Objective Structured Assessment of Technical Skills (OSATS) global rating scale. Absolute and relative improvements during the training curriculum were compared between the groups. A questionnaire evaluated the trainee's opinion on this new training method. Skill improvement on the OSATS global rating scale was significantly greater for the trainees in the INVEST curriculum compared to the MAM, with mean absolute improvement 32.6 versus 14.0 points and mean relative improvement 59.1 versus 34.6% (P=0.02). INVEST significantly enhances technical and procedural skill development during the early learning curve for laparoscopic cholecystectomy. Trainees were positive about the content and the idea of the curriculum.

  12. The role of stenosis ratio as a predictor of surgical satisfaction in patients with lumbar spinal canal stenosis: a receiver-operator characteristic (ROC) curve analysis.

    Science.gov (United States)

    Mohammadi, Hassanreza R; Azimi, Parisa; Benzel, Edward C; Shahzadi, Sohrab; Azhari, Shirzad

    2016-09-01

    The aim of this study was to elucidate independent factors that predict surgical satisfaction in lumbar spinal canal stenosis (LSCS) patients. Patients who underwent surgery were grouped based on the age, gender, duration of symptoms, walking distance, Neurogenic Claudication Outcome Score (NCOS) and the stenosis ratio (SR) described by Lurencin. We recorded on 2-year patient satisfaction using standardized measure. The optimal cut-off points in SR, NCOS and walking distance for predicting surgical satisfaction were estimated from sensitivity and specificity calculations and receiver operator characteristic (ROC) curves. One hundred fifty consecutive patients (51 male, 99 female, mean age 62.4±10.9 years) were followed up for 34±13 months (range 24-49). One, two, three and four level stenosis was observed in 10.7%, 39.3%, 36.0 % and 14.0% of patients, respectively. Post-surgical satisfaction was 78.5% at the 2 years follow up. In ROC curve analysis, the asymptotic significance is less than 0.05 in SR and the optimal cut-off value of SR to predict worsening surgical satisfaction was measured as more than 0.52, with 85.4% sensitivity and 77.4% specificity (AUC 0.798, 95% CI 0.73-0.90; Ppatients with degenerative lumbar stenosis considered for surgical treatment. Using a ROC curve analysis, a radiological feature, the SR, demonstrated superiority in predicting patient satisfaction, compared to functional and clinical characteristics such as walking distance and NCOS.

  13. Learning styles of medical students, general surgery residents, and general surgeons: implications for surgical education

    OpenAIRE

    de Gara Chris; Engels Paul T

    2010-01-01

    Abstract Background Surgical education is evolving under the dual pressures of an enlarging body of knowledge required during residency and mounting work-hour restrictions. Changes in surgical residency training need to be based on available educational models and research to ensure successful training of surgeons. Experiential learning theory, developed by David Kolb, demonstrates the importance of individual learning styles in improving learning. This study helps elucidate the way in which ...

  14. Learning Curve

    Directory of Open Access Journals (Sweden)

    Mary Caponegro

    2012-01-01

    Full Text Available “What’s the matter with Mary Caponegro ?” Françoise Palleau-Papin Were I to introduce Mary Caponegro formally, in an official biographical notice, it would go something like this: Mary Caponegro is the Richard B. Fisher Family Professor in Literature and Writing at Bard College, where William Gaddis once taught. She is the author of five works of fiction: Tales from the Next Village (Lost Roads, 1985, The Star Cafe (Scribner, 1990, Five Doubts (Marsilio, 1998, The Complexities of Intimacy ...

  15. Laparoscopic colorectal surgery in learning curve: Role of implementation of a standardized technique and recovery protocol. A cohort study

    Directory of Open Access Journals (Sweden)

    Gaetano Luglio

    2015-06-01

    Conclusion: Proper laparoscopic colorectal surgery is safe and leads to excellent results in terms of recovery and short term outcomes, even in a learning curve setting. Key factors for better outcomes and shortening the learning curve seem to be the adoption of a standardized technique and training model along with the strict supervision of an expert colorectal surgeon.

  16. Learning styles of medical students, general surgery residents, and general surgeons: implications for surgical education.

    Science.gov (United States)

    Engels, Paul T; de Gara, Chris

    2010-06-30

    Surgical education is evolving under the dual pressures of an enlarging body of knowledge required during residency and mounting work-hour restrictions. Changes in surgical residency training need to be based on available educational models and research to ensure successful training of surgeons. Experiential learning theory, developed by David Kolb, demonstrates the importance of individual learning styles in improving learning. This study helps elucidate the way in which medical students, surgical residents, and surgical faculty learn. The Kolb Learning Style Inventory, which divides individual learning styles into Accommodating, Diverging, Converging, and Assimilating categories, was administered to the second year undergraduate medical students, general surgery resident body, and general surgery faculty at the University of Alberta. A total of 241 faculty, residents, and students were surveyed with an overall response rate of 73%. The predominant learning style of the medical students was assimilating and this was statistically significant (p learning style found in the residents and faculty. The predominant learning styles of the residents and faculty were convergent and accommodative, with no statistically significant differences between the residents and the faculty. We conclude that medical students have a significantly different learning style from general surgical trainees and general surgeons. This has important implications in the education of general surgery residents.

  17. The theoretical base of e-learning and its role in surgical education.

    Science.gov (United States)

    Evgeniou, Evgenios; Loizou, Peter

    2012-01-01

    The advances in Internet and computer technology offer many solutions that can enhance surgical education and increase the effectiveness of surgical teaching. E-learning plays an important role in surgical education today, with many e-learning projects already available on the Internet. E-learning is based on a mixture of educational theories that derive from behaviorist, cognitivist, and constructivist educational theoretical frameworks. CAN EDUCATIONAL THEORY IMPROVE E-LEARNING?: Conventional educational theory can be applied to improve the quality and effectiveness of e-learning. The theory of "threshold concepts" and educational theories on reflection, motivation, and communities of practice can be applied when designing e-learning material. E-LEARNING IN SURGICAL EDUCATION: E-learning has many advantages but also has weaknesses. Studies have shown that e-learning is an effective teaching method that offers high levels of learner satisfaction. Instead of trying to compare e-learning with traditional methods of teaching, it is better to integrate in e-learning elements of traditional teaching that have been proven to be effective. E-learning can play an important role in surgical education as a blended approach, combined with more traditional methods of teaching, which offer better face-to-interaction with patients and colleagues in different circumstances and hands on practice of practical skills. National provision of e-learning can make evaluation easier. The correct utilization of Internet and computer resources combined with the application of valid conventional educational theory to design e-learning relevant to the various levels of surgical training can be effective in the training of future surgeons. Copyright © 2012 Association of Program Directors in Surgery. Published by Elsevier Inc. All rights reserved.

  18. Non-Constant Learning Rates in Retrospective Experience Curve Analyses and their Correlation to Deployment Programs

    Energy Technology Data Exchange (ETDEWEB)

    Wei, Max [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Smith, Sarah J. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Sohn, Michael D. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)

    2015-07-16

    A key challenge for policy-makers and technology market forecasters is to estimate future technology costs and in particular the rate of cost reduction versus production volume. A related, critical question is what role should state and federal governments have in advancing energy efficient and renewable energy technologies? This work provides retrospective experience curves and learning rates for several energy-related technologies, each of which have a known history of federal and state deployment programs. We derive learning rates for eight technologies including energy efficient lighting technologies, stationary fuel cell systems, and residential solar photovoltaics, and provide an overview and timeline of historical deployment programs such as state and federal standards and state and national incentive programs for each technology. Piecewise linear regimes are observed in a range of technology experience curves, and public investments or deployment programs are found to be strongly correlated to an increase in learning rate across multiple technologies. A downward bend in the experience curve is found in 5 out of the 8 energy-related technologies presented here (electronic ballasts, magnetic ballasts, compact fluorescent lighting, general service fluorescent lighting, and the installed cost of solar PV). In each of the five downward-bending experience curves, we believe that an increase in the learning rate can be linked to deployment programs to some degree. This work sheds light on the endogenous versus exogenous contributions to technological innovation and highlights the impact of exogenous government sponsored deployment programs. This work can inform future policy investment direction and can shed light on market transformation and technology learning behavior.

  19. Chest cage angle difference and rotation of main thoracic curve are independent risk factors of postoperative shoulder imbalance in surgically treated patients with adolescent idiopathic scoliosis.

    Science.gov (United States)

    Yagi, Mitsuru; Takemitsu, Masakazu; Machida, Masafumi

    2013-09-01

    Retrospective case series of surgically treated adolescent patients with scoliosis. To assess the prevalence and independent risk factors for postoperative shoulder imbalance in surgically treated adolescent patients with idiopathic scoliosis. Despite recent reports that have identified risk factors for postoperative shoulder imbalance, the relative risks remain unclear. A retrospective review of 85 consecutive patients treated with thoracic fusion with a minimum 2-year follow-up (mean, 3.1 yr) was conducted to investigate the patient radiographical measurements and demographics. Shoulder height difference (SHD) was measured as the graded height difference of the soft tissue shadows. A SHD more than 2 cm indicated an unbalanced shoulder. Patient demographics and radiographical data were studied to determine risk factors for postoperative SHD. The potential risk factors included age, sex, Risser sign, Cobb angle, flexibility, and apical vertebral rotation (AVR) of the main curve, upper-instrumented vertebra level, SHD, and clavicle chest cage angle difference (CCAD). Univariate and multivariate logistic regression analyses were performed to determine the independent risk factors for postoperative shoulder imbalance. Of the 85 patients, 21 patients presented postoperative shoulder imbalance. The univariate analysis indicated age, Risser sign, Cobb angle of the main curve, AVR of the main curve, and CCAD as risk factors, but the multivariate logistic regression analysis showed that only AVR of the main curve and CCAD were independent risk factors for postoperative shoulder imbalance (AVR, P = 0.04, odds ratio (OR): 3.54; CCAD, P = 0.01, OR: 5.10). Postoperative shoulder imbalance was observed in 25% of the surgically treated adolescent patients. The CCAD and AVR of the main thoracic curve were independent risk factors for postoperative shoulder imbalance in surgically treated patients with adolescent idiopathic scoliosis. The significant correlation between CCAD and

  20. A Comparison of a Machine Learning Model with EuroSCORE II in Predicting Mortality after Elective Cardiac Surgery: A Decision Curve Analysis.

    Science.gov (United States)

    Allyn, Jérôme; Allou, Nicolas; Augustin, Pascal; Philip, Ivan; Martinet, Olivier; Belghiti, Myriem; Provenchere, Sophie; Montravers, Philippe; Ferdynus, Cyril

    2017-01-01

    The benefits of cardiac surgery are sometimes difficult to predict and the decision to operate on a given individual is complex. Machine Learning and Decision Curve Analysis (DCA) are recent methods developed to create and evaluate prediction models. We conducted a retrospective cohort study using a prospective collected database from December 2005 to December 2012, from a cardiac surgical center at University Hospital. The different models of prediction of mortality in-hospital after elective cardiac surgery, including EuroSCORE II, a logistic regression model and a machine learning model, were compared by ROC and DCA. Of the 6,520 patients having elective cardiac surgery with cardiopulmonary bypass, 6.3% died. Mean age was 63.4 years old (standard deviation 14.4), and mean EuroSCORE II was 3.7 (4.8) %. The area under ROC curve (IC95%) for the machine learning model (0.795 (0.755-0.834)) was significantly higher than EuroSCORE II or the logistic regression model (respectively, 0.737 (0.691-0.783) and 0.742 (0.698-0.785), p machine learning model, in this monocentric study, has a greater benefit whatever the probability threshold. According to ROC and DCA, machine learning model is more accurate in predicting mortality after elective cardiac surgery than EuroSCORE II. These results confirm the use of machine learning methods in the field of medical prediction.

  1. Innovation and learning curves. Report on knowledge questions of the Working Group Energy and Climate

    International Nuclear Information System (INIS)

    Schoots, K.

    2010-05-01

    This report has been written on account of knowledge questions formulated by the Working Group Energy and Climate. This Working Group has been established in the framework of the Broad Reconsideration of Dutch government policy caused by the economic crisis of 2008-2009. Its task is to investigate the possibilities for a structural reduction of government spending by 20% on sustainable energy, energy saving and fiscal advantages carrying non-sustainable incentives. Apart from that, spending on policies aimed at mitigating climate change are scrutinized. In connection with this task, the working group has formulated knowledge questions which refer to cost effectiveness and possibilities for target achievement, possibilities within the European Renewables Directive and learning curves and innovation. This report addresses the latter two themes: learning curves and innovation. The selection of technologies assessed is not all-embracing, but based on the technologies within the SDE regulation (Dutch regulation on support for sustainable energy) supplemented by some promising innovations. [nl

  2. Does my high blood pressure improve your survival? Overall and subgroup learning curves in health.

    Science.gov (United States)

    Van Gestel, Raf; Müller, Tobias; Bosmans, Johan

    2017-09-01

    Learning curves in health are of interest for a wide range of medical disciplines, healthcare providers, and policy makers. In this paper, we distinguish between three types of learning when identifying overall learning curves: economies of scale, learning from cumulative experience, and human capital depreciation. In addition, we approach the question of how treating more patients with specific characteristics predicts provider performance. To soften collinearity problems, we explore the use of least absolute shrinkage and selection operator regression as a variable selection method and Theil-Goldberger mixed estimation to augment the available information. We use data from the Belgian Transcatheter Aorta Valve Implantation (TAVI) registry, containing information on the first 860 TAVI procedures in Belgium. We find that treating an additional TAVI patient is associated with an increase in the probability of 2-year survival by about 0.16%-points. For adverse events like renal failure and stroke, we find that an extra day between procedures is associated with an increase in the probability for these events by 0.12%-points and 0.07%-points, respectively. Furthermore, we find evidence for positive learning effects from physicians' experience with defibrillation, treating patients with hypertension, and the use of certain types of replacement valves during the TAVI procedure. Copyright © 2017 John Wiley & Sons, Ltd.

  3. Evaluation of the learning curve for external cephalic version using cumulative sum analysis.

    Science.gov (United States)

    Kim, So Yun; Han, Jung Yeol; Chang, Eun Hye; Kwak, Dong Wook; Ahn, Hyun Kyung; Ryu, Hyun Mi; Kim, Moon Young

    2017-07-01

    We evaluated the learning curve for external cephalic version (ECV) using learning curve-cumulative sum (LC-CUSUM) analysis. This was a retrospective study involving 290 consecutive cases between October 2013 and March 2017. We evaluated the learning curve for ECV on nulli and over para 1 group using LC-CUSUM analysis on the assumption that 50% and 70% of ECV procedures succeeded by description a trend-line of quadratic function with reliable R 2 values. The overall success rate for ECV was 64.8% (188/290), while the success rate for nullipara and over para 1 groups was 56.2% (100/178) and 78.6% (88/112), respectively. 'H' value, that the actual failure rate does not differ from the acceptable failure rate, was -3.27 and -1.635 when considering ECV success rates of 50% and 70%, respectively. Consequently, in order to obtain a consistent 50% success rate, we would require 57 nullipara cases, and in order to obtain a consistent 70% success rate, we would require 130 nullipara cases. In contrast, 8 to 10 over para 1 cases would be required for an expected success rate of 50% and 70% on over para 1 group. Even a relatively inexperienced physician can experience success with multipara and after accumulating experience, they will manage nullipara cases. Further research is required for LC-CUSUM involving several practitioners instead of a single practitioner. This will lead to the gradual implementation of standard learning curve guidelines for ECV.

  4. Preliminary Results and Learning Curve of the Minimally Invasive Chevron Akin Operation for Hallux Valgus.

    Science.gov (United States)

    Jowett, Charlie R J; Bedi, Harvinder S

    Minimally invasive surgery is increasing in popularity. It is relevant in hallux valgus surgery owing to the potential for reduced disruption of the soft tissues and improved wound healing. We present our results and assess the learning curve of the minimally invasive Chevron Akin operation for hallux valgus. A total of 120 consecutive feet underwent minimally invasive Chevron Akin for symptomatic hallux valgus, of which 14 were excluded. They were followed up for a mean of 25 (range 18 to 38) months. The patients were clinically assessed using the American Orthopaedic Foot and Ankle Society score. Complications and patient satisfaction were recorded. The radiographs were analyzed and measurements recorded for hallux valgus and intermetatarsal angle correction. The mean age of the patients undergoing surgery was 55 (range 25 to 81) years. Of the 78 patients, 76 (97.4%) were female and 2 (2.6%) were male; 28 (35.9%) cases were bilateral. The mean American Orthopaedic Foot and Ankle Society score improved from 56 (range 23 to 76) preoperatively to 87 (range 50 to 100) postoperatively (p technique. They display a steep associated learning curve. However, the results are promising, and the learning curve is comparable to that for open hallux valgus surgery. Copyright © 2017 American College of Foot and Ankle Surgeons. Published by Elsevier Inc. All rights reserved.

  5. The learning curve of laparoendoscopic single-site (LESS) cholecystectomy: definable, short, and safe.

    Science.gov (United States)

    Hernandez, Jonathan; Ross, Sharona; Morton, Connor; McFarlin, Kellie; Dahal, Sujat; Golkar, Farhaad; Albrink, Michael; Rosemurgy, Alexander

    2010-11-01

    The applications of laparoendoscopic single-site (LESS) surgery, including cholecystectomy, are occurring quickly, although little is generally known about issues associated with the learning curve of this new technique including operative time, conversion rates, and safety. We prospectively followed all patients undergoing LESS cholecystectomy, and compared operations undertaken at our institutions in cohorts of 25 patients with respect to operative times, conversion rates, and complications. One-hundred fifty patients of mean age 46 years underwent LESS cholecystectomy. No significant differences in operative times were demonstrable between any of the 25-patient cohorts operated on at our institution. A significant reduction in operative times (p < 0.001) after completion of 75 LESS procedures was, however, identified with the experience of a single surgeon. No significant reduction in the number of procedures requiring an additional trocar(s) or conversion to open operations was observed after completion of 25 LESS cholecystectomies. Complication rates were low, and not significantly different between any 25-patient cohorts. For surgeons proficient with multi-incision laparoscopic cholecystectomy, the learning curve for LESS cholecystectomy begins near proficiency. Operative complications and conversions were infrequent and unchanged across successive 25-patient cohorts, and were similar to those reported for multi-incision laparoscopic cholecystectomy after the learning curve. Copyright © 2010 American College of Surgeons. Published by Elsevier Inc. All rights reserved.

  6. Learning curve of hysteroscopic placement of tubal sterilization microinserts in 15 gynecologists in the Netherlands.

    Science.gov (United States)

    Janse, Juliënne A; Pattij, Thyrza O S; Eijkemans, Marinus J C; Broekmans, Frank J; Veersema, Sebastiaan; Schreuder, Henk W R

    2013-09-01

    To evaluate the learning curve of hysteroscopic placement of tubal sterilization microinserts by gynecologists in the Netherlands. Prospective multicenter study (Canadian Task Force II-2). Ten community (teaching) hospitals in the Netherlands. A total of 631 women who underwent permanent sterilization by tubal microinserts. Hysteroscopic placement of tubal sterilization microinserts performed by 15 gynecologists experienced in performing operative hysteroscopy, starting from their very first placement. Effect of increasing experience in time on procedure time, pain score, successful bilateral placement, and complications. Bilateral successful placement with confirmation of adequate positioning at follow-up evaluation was achieved in 480 (76.1%) patients at first attempt and in 44 (7.0%) at second attempt. Median procedure time was 8.0 minutes (range: 3-40), and 31 (4.9%) patients were lost to follow-up evaluation. Gravidity showed to be a confounding factor and was consequently adjusted for. A learning curve was seen in a statistically significant decrease of procedure time with increasing experience. The decrease in procedure time extended to 11 to 15 cases and was followed by a plateau phase of the subsequent 60 cases. In contrast, pain scores, successful placement, and complication rate appeared not to improve with increasing experience. A learning curve for hysteroscopic tubal sterilization was seen for procedure time, but successful placement, pain score, and complication rate were not clearly influenced by increasing experience. Copyright © 2013 American Society for Reproductive Medicine. Published by Elsevier Inc. All rights reserved.

  7. Learning styles of medical students, general surgery residents, and general surgeons: implications for surgical education

    Directory of Open Access Journals (Sweden)

    de Gara Chris

    2010-06-01

    Full Text Available Abstract Background Surgical education is evolving under the dual pressures of an enlarging body of knowledge required during residency and mounting work-hour restrictions. Changes in surgical residency training need to be based on available educational models and research to ensure successful training of surgeons. Experiential learning theory, developed by David Kolb, demonstrates the importance of individual learning styles in improving learning. This study helps elucidate the way in which medical students, surgical residents, and surgical faculty learn. Methods The Kolb Learning Style Inventory, which divides individual learning styles into Accommodating, Diverging, Converging, and Assimilating categories, was administered to the second year undergraduate medical students, general surgery resident body, and general surgery faculty at the University of Alberta. Results A total of 241 faculty, residents, and students were surveyed with an overall response rate of 73%. The predominant learning style of the medical students was assimilating and this was statistically significant (p Conclusions We conclude that medical students have a significantly different learning style from general surgical trainees and general surgeons. This has important implications in the education of general surgery residents.

  8. Learning curve of robot-assisted laparoscopic radical prostatectomy for a single experienced surgeon: comparison with simultaneous laparoscopic radical prostatectomy.

    Science.gov (United States)

    Ku, Ja Yoon; Ha, Hong Koo

    2015-04-01

    Despite the large number of analytical reports regarding the learning curve in the transition from open to robot-assisted radical prostatectomy (RARP), few comparative results with laparoscopic radical prostatectomy (LRP) have been reported. Thus, we evaluated operative and postoperative outcomes in RARP versus 100 simultaneously performed LRPs. A single surgeon had performed more than 1,000 laparoscopic operations, including 415 cases of radical nephrectomy, 85 radical cystectomies, 369 radical prostatectomies, and treatment of 212 other urological tumors, since 2009. We evaluated operative (operation time, intraoperative transfusion, complications, hospital stay, margin status, pathological stage, Gleason score) and postoperative (continence and erectile function) parameters in initial cases of RARP without tutoring compared with 100 recently performed LRPs. Mean operation time and length of hospital stay for RARP and LRP were 145.5±43.6 minutes and 118.1±39.1 minutes, and 6.4±0.9 days and 6.6±1.1 days, respectively (p=0.003 and p=0.721). After 17 cases, the mean operation time for RARP was similar to LRP (less than 2 hours). Positive surgical margins in localized cancer were seen in 11.1% and 8.9% of cases in RARP and LRP, respectively (p=0.733). At postoperative 3 months, sexual intercourse was reported in 14.0% and 12.0%, and pad-free continence in 96.0% and 81.0% in patients with RARP and LRP, respectively (p=0.796 and p=0.012). Previous large-volume experience of LRPs may shorten the learning curve for RARP in terms of oncological outcome. Additionally, previous experience with laparoscopy may improve the functional outcomes of RARP.

  9. Clinical experience with the first 40 cases with femtosecond laser cataract surgery technology: safety of the learning curve

    Directory of Open Access Journals (Sweden)

    Joao Crispim

    2015-10-01

    Full Text Available ABSTRACT Objective: To evaluate the introduction of the femtosecond laser (FSL to perform the key steps of the traditional cataract surgery process and the operational difficulties and safety of this new technology during routine use in an operating room in Brazil. Methods A retrospective study was conducted using the first cases operated on at a single center using the laser platform LenSx/Alcon with a soft contact lens patient interface.All patients underwent a detailed preoperative assessment.The anterior capsulotomy, nuclear fragmentation, and corneal incisions were created with the FSL; then, the surgery was completed following the standard phacoemulsification procedure. The main outcome measurements were difficulties and complications related to the learning curve and an analysis of postoperative uncorrected distance visual acuity (UDVA. Results: Of 31 patients (40 eyes, 9 patients had FSL cataract surgery in both eyes.The mean age was 64 ± 12 years (ranging from 42 to 82, the mean cataract nuclear sclerosis was grading 2 ± 0.6 (ranging from 1 to 4, and the preoperative mean UDVA in logMAR was 0.4 ± 0.2 (ranging from 0.1 to 1.3. Anterior capsulotomy was complete in all patients, and scissors were not needed to cut off any intact portion. The postoperative corneal incisions were not completely linear and showed some irregularities. Laser phaco-fragmentation was effective, with the division of the nucleus into smaller segments easily performed before phacoemulsification.After 1 month, the postoperative mean UDVA in logMAR was 0.1 ± 0.1 (ranging from 0.0 to 0.4 (P < 0.0001. Conclusion: With increasing surgical cases and experience, the phacoemulsification steps are performed precisely and effectively with FSL pretreatment, resulting in a safe learning curve.

  10. Scenario analysis for estimating the learning rate of photovoltaic power generation based on learning curve theory in South Korea

    International Nuclear Information System (INIS)

    Hong, Sungjun; Chung, Yanghon; Woo, Chungwon

    2015-01-01

    South Korea, as the 9th largest energy consuming in 2013 and the 7th largest greenhouse gas emitting country in 2011, established ‘Low Carbon Green Growth’ as the national vision in 2008, and is announcing various active energy policies that are set to gain the attention of the world. In this paper, we estimated the decrease of photovoltaic power generation cost in Korea based on the learning curve theory. Photovoltaic energy is one of the leading renewable energy sources, and countries all over the world are currently expanding R and D, demonstration and deployment of photovoltaic technology. In order to estimate the learning rate of photovoltaic energy in Korea, both conventional 1FLC (one-factor learning curve), which considers only the cumulative power generation, and 2FLC, which also considers R and D investment were applied. The 1FLC analysis showed that the cost of power generation decreased by 3.1% as the cumulative power generation doubled. The 2FCL analysis presented that the cost decreases by 2.33% every time the cumulative photovoltaic power generation is doubled and by 5.13% every time R and D investment is doubled. Moreover, the effect of R and D investment on photovoltaic technology took after around 3 years, and the depreciation rate of R and D investment was around 20%. - Highlights: • We analyze the learning effects of photovoltaic energy technology in Korea. • In order to calculate the learning rate, we use 1FLC (one-factor learning curve) and 2FLC methods, respectively. • 1FLC method considers only the cumulative power generation. • 2FLC method considers both cumulative power generation and knowledge stock. • We analyze a variety of scenarios by time lag and depreciation rate of R and D investment

  11. The learning curve of robot-assisted laparoscopic aortofemoral bypass grafting for aortoiliac occlusive disease.

    Science.gov (United States)

    Novotný, Tomáš; Dvorák, Martin; Staffa, Robert

    2011-02-01

    Since the end of the 20th century, robot-assisted surgery has been finding its role among other minimally invasive methods. Vascular surgery seems to be another specialty in which the benefits of this technology can be expected. Our objective was to assess the learning curve of robot-assisted laparoscopic aortofemoral bypass grafting for aortoiliac occlusive disease in a group of 40 patients. Between May 2006 and January 2010, 40 patients (32 men, 8 women), who were a median age of 58 years (range, 48-75 years), underwent 40 robot-assisted laparoscopic aortofemoral reconstructions. Learning curve estimations were used for anastomosis, clamping, and operative time assessment. For conversion rate evaluation, the cumulative summation (CUSUM) technique was used. Statistical analysis comparing the first and second half of our group, and unilateral-to-bilateral reconstructions were performed. We created 21 aortofemoral and 19 aortobifemoral bypasses. The median proximal anastomosis time was 23 minutes (range, 18-50 minutes), median clamping time was 60 minutes (range, 40-95 minutes), and median operative time was 295 minutes (range, 180-475 minutes). The 30-day mortality rate was 0%, and no graft or wound infection or cardiopulmonary or hepatorenal complications were observed. During the median 18-month follow-up (range, 2-48 months), three early graft occlusions occurred (7%). After reoperations, the secondary patency of reconstructions was 100%. Data showed a typical short learning curve for robotic proximal anastomosis creation with anastomosis and clamping time reduction. The operative time learning curve was flat, confirming the procedure's complexity. There were two conversions to open surgery. CUSUM analysis confirmed that an acceptable conversion rate set at 5% was achieved. Comparing the first and second half of our group, all recorded times showed statistically significant improvements. Differences between unilateral and bilateral reconstructions were not

  12. Application of the Learning Curve Analysis to the LHC Main Dipole Production First Assessment

    CERN Document Server

    Fessia, P; Rossi, L

    2006-01-01

    About two third of the LHC main dipoles have been delivered by the three suppliers charged of the production. The training of the staff, mostly hired just for this manufacture, and the natural improvement of the procedures with the acquired experience, decrease naturally the time necessary for the assembly of a unit. The aim of this paper is to apply methodologies like the cost-based learning curves and the time-based learning curves to the LHC Main Dipole comparing the estimated learning percentage to the ones experienced in other industries. This type of analysis, still in a preliminary phase and here applied to about 40% of the total production of the LHC magnets that will end by 2006, shows that our production has a relatively high learning percentage and it is similar to aerospace and complex machine tools for new models. Therefore with the LHC project, accelerator magnets seem to have reached industrial maturity and this production can be used as bench mark for other large scientific projects implying s...

  13. Using peer-assisted learning to teach basic surgical skills: medical students’ experiences

    Directory of Open Access Journals (Sweden)

    Mahdi Saleh

    2013-08-01

    Full Text Available Standard medical curricula in the United Kingdom (UK typically provide basic surgical-skills teaching before medical students are introduced into the clinical environment. However, these sessions are often led by clinical teaching fellows and/or consultants. Depending on the roles undertaken (e.g., session organizers, peer tutors, a peer-assisted learning (PAL approach may afford many benefits to teaching surgical skills. At the University of Keele's School of Medicine, informal PAL is used by the Surgical Society to teach basic surgical skills to pre-clinical students. As medical students who assumed different roles within this peer-assisted model, we present our experiences and discuss the possible implications of incorporating such sessions into UK medical curricula. Our anecdotal evidence suggests that a combination of PAL sessions – used as an adjunct to faculty-led sessions – may provide optimal learning opportunities in delivering a basic surgical skills session for pre-clinical students.

  14. Effective and efficient learning in the operating theater with intraoperative video-enhanced surgical procedure training.

    Science.gov (United States)

    van Det, M J; Meijerink, W J H J; Hoff, C; Middel, B; Pierie, J P E N

    2013-08-01

    INtraoperative Video Enhanced Surgical procedure Training (INVEST) is a new training method designed to improve the transition from basic skills training in a skills lab to procedural training in the operating theater. Traditionally, the master-apprentice model (MAM) is used for procedural training in the operating theater, but this model lacks uniformity and efficiency at the beginning of the learning curve. This study was designed to investigate the effectiveness and efficiency of INVEST compared to MAM. Ten surgical residents with no laparoscopic experience were recruited for a laparoscopic cholecystectomy training curriculum either by the MAM or with INVEST. After a uniform course in basic laparoscopic skills, each trainee performed six cholecystectomies that were digitally recorded. For 14 steps of the procedure, an observer who was blinded for the type of training determined whether the step was performed entirely by the trainee (2 points), partially by the trainee (1 point), or by the supervisor (0 points). Time measurements revealed the total procedure time and the amount of effective procedure time during which the trainee acted as the operating surgeon. Results were compared between both groups. Trainees in the INVEST group were awarded statistically significant more points (115.8 vs. 70.2; p < 0.001) and performed more steps without the interference of the supervisor (46.6 vs. 18.8; p < 0.001). Total procedure time was not lengthened by INVEST, and the part performed by trainees was significantly larger (69.9 vs. 54.1 %; p = 0.004). INVEST enhances effectiveness and training efficiency for procedural training inside the operating theater without compromising operating theater time efficiency.

  15. [Evaluation of the learning curve of residents in localizing a phantom target with ultrasonography].

    Science.gov (United States)

    Dessieux, T; Estebe, J-P; Bloc, S; Mercadal, L; Ecoffey, C

    2008-10-01

    Few information are available regarding the learning curve in ultrasonography and even less for ultrasound-guided regional anesthesia. This study aimed to evaluate in a training program the learning curve on a phantom of 12 residents novice in ultrasonography. Twelve trainees inexperienced in ultrasonography were given introductory training consisting of didactic formation on the various components of the portable ultrasound machine (i.e. on/off button, gain, depth, resolution, and image storage). Then, students performed three trials, in two sets of increased difficulty, at executing these predefined tasks: adjustments of the machine, then localization of a small plastic piece introduced into roasting pork (3 cm below the surface). At the end of the evaluation, the residents were asked to insert a 22 G needle into an exact predetermined target (i.e. point of fascia intersection). The progression of the needle was continuously controlled by ultrasound visualization using injection of a small volume of water (needle perpendicular to the longitudinal plane of the ultrasound beam). Two groups of two different examiners evaluated for each three trials the skill of the residents (quality, time to perform the machine adjustments, to localize the plastic target, and to hydrolocalize, and volume used for hydrolocalization). After each trial, residents evaluated their performance using a difficulty scale (0: easy to 10: difficult). All residents performed the adjustments from the last trial of each set, with a learning curve observed in terms of duration. Localization of the plastic piece was achieved by all residents at the 6th trial, with a shorter duration of localization. Hydrolocalization was achieved after the 4th trial by all subjects. Difficulty scale was correlated to the number of trials. All these results were independent of the experience of residents in regional anesthesia. Four trials were necessary to adjust correctly the machine, to localize a target, and to

  16. Learning curves and long-term outcome of simulation-based thoracentesis training for medical students

    Science.gov (United States)

    2011-01-01

    Background Simulation-based medical education has been widely used in medical skills training; however, the effectiveness and long-term outcome of simulation-based training in thoracentesis requires further investigation. The purpose of this study was to assess the learning curve of simulation-based thoracentesis training, study skills retention and transfer of knowledge to a clinical setting following simulation-based education intervention in thoracentesis procedures. Methods Fifty-two medical students were enrolled in this study. Each participant performed five supervised trials on the simulator. Participant's performance was assessed by performance score (PS), procedure time (PT), and participant's confidence (PC). Learning curves for each variable were generated. Long-term outcome of the training was measured by the retesting and clinical performance evaluation 6 months and 1 year, respectively, after initial training on the simulator. Results Significant improvements in PS, PT, and PC were noted among the first 3 to 4 test trials (p 0.05). Clinical competency in thoracentesis was improved in participants who received simulation training relative to that of first year medical residents without such experience (p simulation-based thoracentesis training can significantly improve an individual's performance. The saturation of learning from the simulator can be achieved after four practice sessions. Simulation-based training can assist in long-term retention of skills and can be partially transferred to clinical practice. PMID:21696584

  17. An introduction to electronic learning and its use to address challenges in surgical training.

    Science.gov (United States)

    Baran, Szczepan W; Johnson, Elizabeth J; Kehler, James

    2009-06-01

    The animal research community faces a shortage of surgical training opportunities along with an increasing demand for expertise in surgical techniques. One possible means of overcoming this challenge is the use of computer-based or electronic learning (e-learning) to disseminate material to a broad range of animal users. E-learning platforms can take many different forms, ranging from simple text documents that are posted online to complex virtual courses that incorporate dynamic video or audio content and in which students and instructors can interact in real time. The authors present an overview of e-learning and discuss its potential benefits as a supplement to hands-on rodent surgical training. They also discuss a few basic considerations in developing and implementing electronic courses.

  18. Overcoming the learning curve of single-port total laparoscopic hysterectomy with barbed suture: a single surgeon's initial experience.

    Science.gov (United States)

    Lee, Yoon Hee; Chong, Gun Oh; Kim, Mi Ju; Gy Hong, Dae; Lee, Yoon Soon

    2017-09-01

    Single-port total laparoscopic hysterectomy (TLH) has not been widely used because of its technical difficulty and steep learning curve, especially the laparoscopic suturing of the vaginal stump. Barbed suturing is a new technology that has the potential to greatly facilitate laparoscopic suturing. To compare surgical outcomes and vaginal vault healing between barbed sutures and traditional sutures in the repair of the vaginal vault during single-port TLH. Between August 2013 and June 2015, we performed single-port TLH in 85 consecutive patients for benign or premalignant gynecological conditions. The first 48 patients underwent single-port TLH with traditional interrupted sutures, and the next 37 patients underwent single-port TLH with absorbable unidirectional knotless barbed sutures for repair of the vaginal vault. The patient characteristics (age, body mass index), procedures performed, uterine weight, and uterine disease were similar between the groups. There were no differences in blood loss, hemoglobin change, length of hospital stay, or perioperative complications. Operative time and the time required for vaginal cuff suturing were significantly shorter in the barbed suture group than in the traditional suture group (57.8 ±13.5 vs. 80.1 ±18.7 min, p < 0.001; 5.5 ±1.7 vs. 12.9 ±3.5 min, p < 0.001). Moreover, the use of barbed sutures significantly reduced the incidence of vaginal granulation tissue formation (2.7% vs. 35.4%, p < 0.001). Use of barbed sutures in single-port TLH reduced the operative time, suturing time of the vaginal vault, and formation of vaginal granulation tissue. Barbed suturing may help overcome surgical difficulties and vaginal cuff complications.

  19. Surgical robotics beyond enhanced dexterity instrumentation: a survey of machine learning techniques and their role in intelligent and autonomous surgical actions.

    Science.gov (United States)

    Kassahun, Yohannes; Yu, Bingbin; Tibebu, Abraham Temesgen; Stoyanov, Danail; Giannarou, Stamatia; Metzen, Jan Hendrik; Vander Poorten, Emmanuel

    2016-04-01

    Advances in technology and computing play an increasingly important role in the evolution of modern surgical techniques and paradigms. This article reviews the current role of machine learning (ML) techniques in the context of surgery with a focus on surgical robotics (SR). Also, we provide a perspective on the future possibilities for enhancing the effectiveness of procedures by integrating ML in the operating room. The review is focused on ML techniques directly applied to surgery, surgical robotics, surgical training and assessment. The widespread use of ML methods in diagnosis and medical image computing is beyond the scope of the review. Searches were performed on PubMed and IEEE Explore using combinations of keywords: ML, surgery, robotics, surgical and medical robotics, skill learning, skill analysis and learning to perceive. Studies making use of ML methods in the context of surgery are increasingly being reported. In particular, there is an increasing interest in using ML for developing tools to understand and model surgical skill and competence or to extract surgical workflow. Many researchers begin to integrate this understanding into the control of recent surgical robots and devices. ML is an expanding field. It is popular as it allows efficient processing of vast amounts of data for interpreting and real-time decision making. Already widely used in imaging and diagnosis, it is believed that ML will also play an important role in surgery and interventional treatments. In particular, ML could become a game changer into the conception of cognitive surgical robots. Such robots endowed with cognitive skills would assist the surgical team also on a cognitive level, such as possibly lowering the mental load of the team. For example, ML could help extracting surgical skill, learned through demonstration by human experts, and could transfer this to robotic skills. Such intelligent surgical assistance would significantly surpass the state of the art in surgical

  20. Learning of couplings for random asymmetric kinetic Ising models revisited: random correlation matrices and learning curves

    International Nuclear Information System (INIS)

    Bachschmid-Romano, Ludovica; Opper, Manfred

    2015-01-01

    We study analytically the performance of a recently proposed algorithm for learning the couplings of a random asymmetric kinetic Ising model from finite length trajectories of the spin dynamics. Our analysis shows the importance of the nontrivial equal time correlations between spins induced by the dynamics for the speed of learning. These correlations become more important as the spin’s stochasticity is decreased. We also analyse the deviation of the estimation error (paper)

  1. From curve fitting to machine learning an illustrative guide to scientific data analysis and computational intelligence

    CERN Document Server

    Zielesny, Achim

    2016-01-01

    This successful book provides in its second edition an interactive and illustrative guide from two-dimensional curve fitting to multidimensional clustering and machine learning with neural networks or support vector machines. Along the way topics like mathematical optimization or evolutionary algorithms are touched. All concepts and ideas are outlined in a clear cut manner with graphically depicted plausibility arguments and a little elementary mathematics. The major topics are extensively outlined with exploratory examples and applications. The primary goal is to be as illustrative as possible without hiding problems and pitfalls but to address them. The character of an illustrative cookbook is complemented with specific sections that address more fundamental questions like the relation between machine learning and human intelligence. All topics are completely demonstrated with the computing platform Mathematica and the Computational Intelligence Packages (CIP), a high-level function library developed with M...

  2. Evaluation matters: lessons learned on the evaluation of surgical teaching.

    Science.gov (United States)

    Woods, Nicole N

    2011-01-01

    The traditional system of academic promotion and tenure can make it difficult to reward those who excel at surgical teaching. A successful faculty evaluation process can provide the objective measures of teaching performance needed for performance appraisals and promotion decisions. Over the course of two decades, an extensive faculty evaluation process has been developed in the Department of Surgery at the University of Toronto. This paper presents some of the non-psychometric characteristics of that system. Faculty awareness of the evaluation process, the consistency of its application, trainee anonymity and the materiality of the results are described key factors of a faculty evaluation system that meets the assessment needs of individual teachers and raises the profile of teaching in surgical departments. Copyright © 2010 Royal College of Surgeons of Edinburgh (Scottish charity number SC005317) and Royal College of Surgeons in Ireland. Published by Elsevier Ltd. All rights reserved.

  3. Defining the learning curve of laparoendoscopic single-site Heller myotomy.

    Science.gov (United States)

    Ross, Sharona B; Luberice, Kenneth; Kurian, Tony J; Paul, Harold; Rosemurgy, Alexander S

    2013-08-01

    Initial outcomes suggest laparoendoscopic single-site (LESS) Heller myotomy with anterior fundoplication provides safe, efficacious, and cosmetically superior outcomes relative to conventional laparoscopy. This study was undertaken to define the learning curve of LESS Heller myotomy with anterior fundoplication. One hundred patients underwent LESS Heller myotomy with anterior fundoplication. Symptom frequency and severity were scored using a Likert scale (0 = never/not bothersome to 10 = always/very bothersome). Symptom resolution, additional trocars, and complications were compared among patient quartiles. Median data are presented. Preoperative frequency/severity scores were: dysphagia = 10/8 and regurgitation = 8/7. Additional trocars were placed in 12 patients (10%), of whom all were in the first two quartiles. Esophagotomy/gastrotomy occurred in three patients. Postoperative complications occurred in 9 per cent. No conversions to "open" operations occurred. Length of stay was 1 day. Postoperative frequency/severity scores were: dysphagia = 2/0 and regurgitation = 0/0; scores were less than before myotomy (P Heller myotomy with anterior fundoplication well palliates symptoms of achalasia with no apparent scar. Placement of additional trocars only occurred early in the experience. For surgeons proficient with the conventional laparoscopic approach, the learning curve of LESS Heller myotomy with anterior fundoplication is short and safe, because proficiency is quickly attained.

  4. Cognitive learning and its future in urology: surgical skills teaching and assessment.

    Science.gov (United States)

    Shafiei, Somayeh B; Hussein, Ahmed A; Guru, Khurshid A

    2017-07-01

    The aim of this study is to provide an overview of the current status of novel cognitive training approaches in surgery and to investigate the potential role of cognitive training in surgical education. Kinematics of end-effector trajectories, as well as cognitive state features of surgeon trainees and mentors have recently been studied as modalities to objectively evaluate the expertise level of trainees and to shorten the learning process. Virtual reality and haptics also have shown promising in research results in improving the surgical learning process by providing feedback to the trainee. 'Cognitive training' is a novel approach to enhance training and surgical performance. The utility of cognitive training in improving motor skills in other fields, including sports and rehabilitation, is promising enough to justify its utilization to improve surgical performance. However, some surgical procedures, especially ones performed during human-robot interaction in robot-assisted surgery, are much more complicated than sport and rehabilitation. Cognitive training has shown promising results in surgical skills-acquisition in complicated environments such as surgery. However, these methods are mostly developed in research groups using limited individuals. Transferring this research into the clinical applications is a demanding challenge. The aim of this review is to provide an overview of the current status of these novel cognitive training approaches in surgery and to investigate the potential role of cognitive training in surgical education.

  5. Survival curves after X-ray and heat treatments for melanoma cells derived directly from surgical specimens of tumours in man

    International Nuclear Information System (INIS)

    Rofstad, E.K.; Wahl, A.; Tveit, K.M.; Monge, O.R.; Brustad, T.

    1985-01-01

    X-ray and heat survival curves were established for melanoma cells derived directly from surgical specimens of tumours in man by using the Courtenay soft agar colony assay. The plating efficiency for 11 of the 14 melanomas studied was sufficiently high (PE = 0.3-58%) to measure cell survival over at least two decades. Experiments repeated with cells stored in liquid nitrogen showed that the survival assay gave highly reproducible results. The melanomas exhibited individual and characteristic survival curves whether exposed to radiation or heat (43.5 0 C). The D 0 -values were in the ranges 0.63-1.66 Gy (X-rays) and 33-58 min (heat). The survival curves were similar to those reported previously for human melanoma xenografts. The radiation sensitivity of the cells was not correlated to the heat sensitivity. Since the melanomas appeared to be very heterogeneous in radiation response in vitro as melanomas are known to be clinically, it is suggested that melanomas may be suitable for prospective studies aimed at establishing whether clinical radioreponsiveness somehow is related to in vitro survival curve parameters. (orig.)

  6. Analyzing the Learning Path of US Shale Players by Using the Learning Curve Method

    Directory of Open Access Journals (Sweden)

    Jong-Hyun Kim

    2017-12-01

    Full Text Available The US shale exploration and production (E&P industry has grown since 2007 due to the development of new techniques such as hydraulic fracturing and horizontal drilling. As a result, the share of shale gas in the US natural gas production is almost 50%, and the share of tight oil in the US crude oil production is almost 52%. Even though oil and gas prices decreased sharply in 2014, the production amounts of shale gas and tight oil increased between 2014 and 2015. We show that many players in the US shale E&P industry succeeded in decreasing their production costs to maintain their business activity and production. However, most of the companies in the US petroleum E&P industry incurred losses in 2015 and 2016. Furthermore, crude oil and natural gas prices could not rebound to their 2015 price levels. Therefore, many companies in the US petroleum E&P industry need to increase their productivity to overcome the low commodity prices situation. Hence, to test the change in their productivity and analyze their ability to survive in the petroleum industry, this study calculates the learning rate using the US shale E&P players’ annual report data from 2008 to 2016. The result of the calculation is that the long-term learning rate is 1.87% and the short-term learning rate is 3.16%. This indicates a change in the technological development trend.

  7. Laparoscopy Instructional Videos: The Effect of Preoperative Compared With Intraoperative Use on Learning Curves.

    Science.gov (United States)

    Broekema, Theo H; Talsma, Aaldert K; Wevers, Kevin P; Pierie, Jean-Pierre E N

    Previous studies have shown that the use of intraoperative instructional videos has a positive effect on learning laparoscopic procedures. This study investigated the effect of the timing of the instructional videos on learning curves in laparoscopic skills training. After completing a basic skills course on a virtual reality simulator, medical students and residents with less than 1 hour experience using laparoscopic instruments were randomized into 2 groups. Using an instructional video either preoperatively or intraoperatively, both groups then performed 4 repetitions of a standardized task on the TrEndo augmented reality. With the TrEndo, 9 motion analysis parameters (MAPs) were recorded for each session (4 MAPs for each hand and time). These were the primary outcome measurements for performance. The time spent watching the instructional video was also recorded. Improvement in performance was studied within and between groups. Medical Center Leeuwarden, a secondary care hospital located in Leeuwarden, The Netherlands. Right-hand dominant medical student and residents with more than 1 hour experience operating any kind of laparoscopic instruments were participated. A total of 23 persons entered the study, of which 21 completed the study course. In both groups, at least 5 of 9 MAPs showed significant improvements between repetition 1 and 4. When both groups were compared after completion of repetition 4, no significant differences in improvement were detected. The intraoperative group showed significant improvement in 3 MAPs of the left-nondominant-hand, compared with one MAP for the preoperative group. No significant differences in learning curves could be detected between the subjects who used intraoperative instructional videos and those who used preoperative instructional videos. Intraoperative video instruction may result in improved dexterity of the nondominant hand. Copyright © 2016 Association of Program Directors in Surgery. Published by Elsevier Inc

  8. Development Process and Technical Aspects of Laparoscopic Hepatectomy: Learning Curve Based on 15 Years of Experience.

    Science.gov (United States)

    Komatsu, Shohei; Scatton, Olivier; Goumard, Claire; Sepulveda, Ailton; Brustia, Raffaele; Perdigao, Fabiano; Soubrane, Olivier

    2017-05-01

    Laparoscopic hepatectomy continues to be a challenging operation associated with a steep learning curve. This study aimed to evaluate the learning process during 15 years of experience with laparoscopic hepatectomy and to identify approaches to standardization of this procedure. Prospectively collected data of 317 consecutive laparoscopic hepatectomies performed from January 2000 to December 2014 were reviewed retrospectively. The operative procedures were classified into 4 categories (minor hepatectomy, left lateral sectionectomy [LLS], left hepatectomy, and right hepatectomy), and indications were classified into 5 categories (benign-borderline tumor, living donor, metastatic liver tumor, biliary malignancy, and hepatocellular carcinoma). During the first 10 years, the procedures were limited mainly to minor hepatectomy and LLS, and the indications were limited to benign-borderline tumor and living donor. Implementation of major hepatectomy rapidly increased the proportion of malignant tumors, especially hepatocellular carcinoma, starting from 2011. Conversion rates decreased with experience for LLS (13.3% vs 3.4%; p = 0.054) and left hepatectomy (50.0% vs 15.0%; p = 0.012), but not for right hepatectomy (41.4% vs 35.7%; p = 0.661). Our 15-year experience clearly demonstrates the stepwise procedural evolution from LLS through left hepatectomy to right hepatectomy, as well as the trend in indications from benign-borderline tumor/living donor to malignant tumors. In contrast to LLS and left hepatectomy, a learning curve was not observed for right hepatectomy. The ongoing development process can contribute to faster standardization necessary for future advances in laparoscopic hepatectomy. Copyright © 2017 American College of Surgeons. Published by Elsevier Inc. All rights reserved.

  9. Establishing the minimal number of virtual reality simulator training sessions necessary to develop basic laparoscopic skills competence: evaluation of the learning curve

    Directory of Open Access Journals (Sweden)

    Ricardo Jordao Duarte

    2013-09-01

    Full Text Available Introduction Medical literature is scarce on information to define a basic skills training program for laparoscopic surgery (peg and transferring, cutting, clipping. The aim of this study was to determine the minimal number of simulator sessions of basic laparoscopic tasks necessary to elaborate an optimal virtual reality training curriculum. Materials and Methods Eleven medical students with no previous laparoscopic experience were spontaneously enrolled. They were submitted to simulator training sessions starting at level 1 (Immersion Lap VR, San Jose, CA, including sequentially camera handling, peg and transfer, clipping and cutting. Each student trained twice a week until 10 sessions were completed. The score indexes were registered and analyzed. The total of errors of the evaluation sequences (camera, peg and transfer, clipping and cutting were computed and thereafter, they were correlated to the total of items evaluated in each step, resulting in a success percent ratio for each student for each set of each completed session. Thereafter, we computed the cumulative success rate in 10 sessions, obtaining an analysis of the learning process. By non-linear regression the learning curve was analyzed. Results By the non-linear regression method the learning curve was analyzed and a r2 = 0.73 (p < 0.001 was obtained, being necessary 4.26 (∼five sessions to reach the plateau of 80% of the estimated acquired knowledge, being that 100% of the students have reached this level of skills. From the fifth session till the 10th, the gain of knowledge was not significant, although some students reached 96% of the expected improvement. Conclusions This study revealed that after five simulator training sequential sessions the students' learning curve reaches a plateau. The forward sessions in the same difficult level do not promote any improvement in laparoscopic basic surgical skills, and the students should be introduced to a more difficult training

  10. Establishing the minimal number of virtual reality simulator training sessions necessary to develop basic laparoscopic skills competence: evaluation of the learning curve.

    Science.gov (United States)

    Duarte, Ricardo Jordão; Cury, José; Oliveira, Luis Carlos Neves; Srougi, Miguel

    2013-01-01

    Medical literature is scarce on information to define a basic skills training program for laparoscopic surgery (peg and transferring, cutting, clipping). The aim of this study was to determine the minimal number of simulator sessions of basic laparoscopic tasks necessary to elaborate an optimal virtual reality training curriculum. Eleven medical students with no previous laparoscopic experience were spontaneously enrolled. They were submitted to simulator training sessions starting at level 1 (Immersion Lap VR, San Jose, CA), including sequentially camera handling, peg and transfer, clipping and cutting. Each student trained twice a week until 10 sessions were completed. The score indexes were registered and analyzed. The total of errors of the evaluation sequences (camera, peg and transfer, clipping and cutting) were computed and thereafter, they were correlated to the total of items evaluated in each step, resulting in a success percent ratio for each student for each set of each completed session. Thereafter, we computed the cumulative success rate in 10 sessions, obtaining an analysis of the learning process. By non-linear regression the learning curve was analyzed. By the non-linear regression method the learning curve was analyzed and a r2 = 0.73 (p sessions) to reach the plateau of 80% of the estimated acquired knowledge, being that 100% of the students have reached this level of skills. From the fifth session till the 10th, the gain of knowledge was not significant, although some students reached 96% of the expected improvement. This study revealed that after five simulator training sequential sessions the students' learning curve reaches a plateau. The forward sessions in the same difficult level do not promote any improvement in laparoscopic basic surgical skills, and the students should be introduced to a more difficult training tasks level.

  11. Optimizing area under the ROC curve using semi-supervised learning.

    Science.gov (United States)

    Wang, Shijun; Li, Diana; Petrick, Nicholas; Sahiner, Berkman; Linguraru, Marius George; Summers, Ronald M

    2015-01-01

    Receiver operating characteristic (ROC) analysis is a standard methodology to evaluate the performance of a binary classification system. The area under the ROC curve (AUC) is a performance metric that summarizes how well a classifier separates two classes. Traditional AUC optimization techniques are supervised learning methods that utilize only labeled data (i.e., the true class is known for all data) to train the classifiers. In this work, inspired by semi-supervised and transductive learning, we propose two new AUC optimization algorithms hereby referred to as semi-supervised learning receiver operating characteristic (SSLROC) algorithms, which utilize unlabeled test samples in classifier training to maximize AUC. Unlabeled samples are incorporated into the AUC optimization process, and their ranking relationships to labeled positive and negative training samples are considered as optimization constraints. The introduced test samples will cause the learned decision boundary in a multidimensional feature space to adapt not only to the distribution of labeled training data, but also to the distribution of unlabeled test data. We formulate the semi-supervised AUC optimization problem as a semi-definite programming problem based on the margin maximization theory. The proposed methods SSLROC1 (1-norm) and SSLROC2 (2-norm) were evaluated using 34 (determined by power analysis) randomly selected datasets from the University of California, Irvine machine learning repository. Wilcoxon signed rank tests showed that the proposed methods achieved significant improvement compared with state-of-the-art methods. The proposed methods were also applied to a CT colonography dataset for colonic polyp classification and showed promising results.

  12. Learning curves of theta/beta neurofeedback in children with ADHD.

    Science.gov (United States)

    Janssen, Tieme W P; Bink, Marleen; Weeda, Wouter D; Geladé, Katleen; van Mourik, Rosa; Maras, Athanasios; Oosterlaan, Jaap

    2017-05-01

    Neurofeedback is widely applied as non-pharmacological intervention aimed at reducing symptoms of ADHD, even though efficacy has not been unequivocally established. Neuronal changes during the neurofeedback intervention that resemble learning can provide crucial evidence for the feasibility and specificity of this intervention. A total of 38 children (aged between 7 and 13 years) with a DSM-IV-TR diagnosis of ADHD, completed on average 29 sessions of theta (4-8 Hz)/beta (13-20 Hz) neurofeedback training. Dependent variables included training-related measures as well as theta and beta power during baseline and training runs for each session. Learning effects were analyzed both within and between sessions. To further specify findings, individual learning curves were explored and correlated with behavioral changes in ADHD symptoms. Over the course of the training, there was a linear increase in participants' mean training level, highest obtained training level and the number of earned credits (range b = 0.059, -0.750, p neurofeedback, although a lack of behavioral correlates may indicate insufficient transfer to daily functioning, or to confounding reinforcement of electromyographic activity. This trial is registered at the US National Institutes of Health (ClinicalTrials.gov, ref. no: NCT01363544); https://clinicaltrials.gov/show/NCT01363544 .

  13. Development of the Mathematics of Learning Curve Models for Evaluating Small Modular Reactor Economics

    Energy Technology Data Exchange (ETDEWEB)

    Harrison, T. J. [ORNL

    2014-02-01

    The cost of nuclear power is a straightforward yet complicated topic. It is straightforward in that the cost of nuclear power is a function of the cost to build the nuclear power plant, the cost to operate and maintain it, and the cost to provide fuel for it. It is complicated in that some of those costs are not necessarily known, introducing uncertainty into the analysis. For large light water reactor (LWR)-based nuclear power plants, the uncertainty is mainly contained within the cost of construction. The typical costs of operations and maintenance (O&M), as well as fuel, are well known based on the current fleet of LWRs. However, the last currently operating reactor to come online was Watts Bar 1 in May 1996; thus, the expected construction costs for gigawatt (GW)-class reactors in the United States are based on information nearly two decades old. Extrapolating construction, O&M, and fuel costs from GW-class LWRs to LWR-based small modular reactors (SMRs) introduces even more complication. The per-installed-kilowatt construction costs for SMRs are likely to be higher than those for the GW-class reactors based on the property of the economy of scale. Generally speaking, the economy of scale is the tendency for overall costs to increase slower than the overall production capacity. For power plants, this means that doubling the power production capacity would be expected to cost less than twice as much. Applying this property in the opposite direction, halving the power production capacity would be expected to cost more than half as much. This can potentially make the SMRs less competitive in the electricity market against the GW-class reactors, as well as against other power sources such as natural gas and subsidized renewables. One factor that can potentially aid the SMRs in achieving economic competitiveness is an economy of numbers, as opposed to the economy of scale, associated with learning curves. The basic concept of the learning curve is that the more a

  14. [Simulation in surgical training].

    Science.gov (United States)

    Nabavi, A; Schipper, J

    2017-01-01

    Patient safety during operations hinges on the surgeon's skills and abilities. However, surgical training has come under a variety of restrictions. To acquire dexterity with decreasingly "simple" cases, within the legislative time constraints and increasing expectations for surgical results is the future challenge. Are there alternatives to traditional master-apprentice learning? A literature review and analysis of the development, implementation, and evaluation of surgical simulation are presented. Simulation, using a variety of methods, most important physical and virtual (computer-generated) models, provides a safe environment to practice basic and advanced skills without endangering patients. These environments have specific strengths and weaknesses. Simulations can only serve to decrease the slope of learning curves, but cannot be a substitute for the real situation. Thus, they have to be an integral part of a comprehensive training curriculum. Our surgical societies have to take up that challenge to ensure the training of future generations.

  15. Computer-enhanced visual learning method: a paradigm to teach and document surgical skills.

    Science.gov (United States)

    Maizels, Max; Mickelson, Jennie; Yerkes, Elizabeth; Maizels, Evelyn; Stork, Rachel; Young, Christine; Corcoran, Julia; Holl, Jane; Kaplan, William E

    2009-09-01

    Changes in health care are stimulating residency training programs to develop new methods for teaching surgical skills. We developed Computer-Enhanced Visual Learning (CEVL) as an innovative Internet-based learning and assessment tool. The CEVL method uses the educational procedures of deliberate practice and performance to teach and learn surgery in a stylized manner. CEVL is a learning and assessment tool that can provide students and educators with quantitative feedback on learning a specific surgical procedure. Methods involved examine quantitative data of improvement in surgical skills. Herein, we qualitatively describe the method and show how program directors (PDs) may implement this technique in their residencies. CEVL allows an operation to be broken down into teachable components. The process relies on feedback and remediation to improve performance, with a focus on learning that is applicable to the next case being performed. CEVL has been shown to be effective for teaching pediatric orchiopexy and is being adapted to additional adult and pediatric procedures and to office examination skills. The CEVL method is available to other residency training programs.

  16. Digital tomosynthesis for evaluating metastatic lung nodules: Nodule visibility, learning curves, and reading times

    International Nuclear Information System (INIS)

    Lee, Kyung Hee; Goo, Jin Mo; Lee, Sang Min; Park, Chang Min; Bahn, Young Eun; Kim, Hyung Jin; Song, Yong Sub; Hwang, Eui Jin

    2015-01-01

    To evaluate nodule visibility, learning curves, and reading times for digital tomosynthesis (DT). We included 80 patients who underwent computed tomography (CT) and DT before pulmonary metastasectomy. One experienced chest radiologist annotated all visible nodules on thin-section CT scans using computer-aided detection software. Two radiologists used CT as the reference standard and retrospectively graded the visibility of nodules on DT. Nodule detection performance was evaluated in four sessions of 20 cases each by six readers. After each session, readers were unblinded to the DT images by revealing the true-positive markings and were instructed to self-analyze their own misreads. Receiver-operating-characteristic curves were determined. Among 414 nodules on CT, 53.3% (221/414) were visible on DT. The main reason for not seeing a nodule on DT was small size (93.3%, < or = 5 mm). DT revealed a substantial number of malignant nodules (84.1%, 143/170). The proportion of malignant nodules among visible nodules on DT was significantly higher (64.7%, 143/221) than that on CT (41.1%, 170/414) (p < 0.001). Area under the curve (AUC) values at the initial session were > 0.8, and the average detection rate for malignant nodules was 85% (210/246). The inter-session analysis of the AUC showed no significant differences among the readers, and the detection rate for malignant nodules did not differ across sessions. A slight improvement in reading times was observed. Most malignant nodules > 5 mm were visible on DT. As nodule detection performance was high from the initial session, DT may be readily applicable for radiology residents and board-certified radiologists.

  17. Digital tomosynthesis for evaluating metastatic lung nodules: Nodule visibility, learning curves, and reading times

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Kyung Hee; Goo, Jin Mo; Lee, Sang Min; Park, Chang Min; Bahn, Young Eun; Kim, Hyung Jin; Song, Yong Sub; Hwang, Eui Jin [Dept. of Radiology, Seoul National University College of Medicine, and Institute of Radiation Medicine, Seoul National University Medical Research Center, Seoul (Korea, Republic of)

    2015-04-15

    To evaluate nodule visibility, learning curves, and reading times for digital tomosynthesis (DT). We included 80 patients who underwent computed tomography (CT) and DT before pulmonary metastasectomy. One experienced chest radiologist annotated all visible nodules on thin-section CT scans using computer-aided detection software. Two radiologists used CT as the reference standard and retrospectively graded the visibility of nodules on DT. Nodule detection performance was evaluated in four sessions of 20 cases each by six readers. After each session, readers were unblinded to the DT images by revealing the true-positive markings and were instructed to self-analyze their own misreads. Receiver-operating-characteristic curves were determined. Among 414 nodules on CT, 53.3% (221/414) were visible on DT. The main reason for not seeing a nodule on DT was small size (93.3%, < or = 5 mm). DT revealed a substantial number of malignant nodules (84.1%, 143/170). The proportion of malignant nodules among visible nodules on DT was significantly higher (64.7%, 143/221) than that on CT (41.1%, 170/414) (p < 0.001). Area under the curve (AUC) values at the initial session were > 0.8, and the average detection rate for malignant nodules was 85% (210/246). The inter-session analysis of the AUC showed no significant differences among the readers, and the detection rate for malignant nodules did not differ across sessions. A slight improvement in reading times was observed. Most malignant nodules > 5 mm were visible on DT. As nodule detection performance was high from the initial session, DT may be readily applicable for radiology residents and board-certified radiologists.

  18. The Learning Curve in neurofeedback of Peter Van Deusen: A review article

    Directory of Open Access Journals (Sweden)

    Valdenilson Ribeiro Ribas

    Full Text Available ABSTRACT The Learning Curve (TLC in neurofeedback concept emerged after Peter Van Deusen compiled the results of articles on the expected electrical activity of the brain. This concept was subsequently tested on patients at four clinics in Atlanta between 1994 and 2001. The aim of this paper was to report the historical aspects of TLC. Articles published on the electronic databases MEDLINE/PubMed and Web of Science were reviewed. During patient evaluation, TLC investigates categories called disconnected, hot temporal lobes, reversal of alpha and beta waves, blocking, locking, and filtering or processing. This enables neuroscientists to use their training designs and, by means of behavioral psychology, to work on neuroregulation, as self-regulation for patients. TLC shows the relationships between electrical, mental and behavioral activity in patients. It also identifies details of patterns that can assist physicians in their choice of treatment.

  19. Preoperative risk factors for conversion and learning curve of minimally invasive distal pancreatectomy.

    Science.gov (United States)

    Hua, Yongfei; Javed, Ammar A; Burkhart, Richard A; Makary, Martin A; Weiss, Matthew J; Wolfgang, Christopher L; He, Jin

    2017-11-01

    Although laparoscopic distal pancreatectomy is considered a standard approach, 10% to 40% of these are converted. The preoperative risk factors for conversion are not well described. The aim of this study was to identify risk factors associated with conversion. Clinicopathological variables of 211 consecutive patients who underwent laparoscopic distal pancreatectomy between January 2007 and December 2015 at Johns Hopkins were analyzed to identify factors associated with conversion. Furthermore, the learning curve for laparoscopic distal pancreatectomy was studied. On univariate analysis of diabetes mellitus, preoperative diagnosis of malignant disease, multiorgan resection, surgeons' years and case experience were significantly associated with conversion (all P pancreatectomy with a preoperative diagnosis of malignant disease or possible multiorgan resection are at a higher risk of conversion. Surgeon experience of performing >15 procedures significantly reduces the risk of conversion. Copyright © 2017 Elsevier Inc. All rights reserved.

  20. Kant, curves and medical learning practice: a reply to Le Morvan and Stock.

    Science.gov (United States)

    Ives, J

    2007-02-01

    In a recent paper published in the Journal of Medical Ethics, Le Morvan and Stock claim that the kantian ideal of treating people always as ends in themselves and never merely as a means is in direct and insurmountable conflict with the current medical practice of allowing practitioners at the bottom of their "learning curve" to "practise their skills" on patients. In this response, I take up the challenge they issue [corrected] and try to reconcile this conflict. The kantian ideal offered in the paper is an incomplete characterisation of Kant's moral philosophy, and the formula of humanity is considered in isolation without taking into account other salient kantian principles. I also suggest that their argument based on "necessary for the patient" assumes too narrow a reading of "necessary". This reply is intended as an extension to, rather than a criticism of, their work.

  1. Effects of Flipped Learning Using Online Materials in a Surgical Nursing Practicum: A Pilot Stratified Group-Randomized Trial.

    Science.gov (United States)

    Lee, Myung Kyung; Park, Bu Kyung

    2018-01-01

    This study examined the effect of flipped learning in comparison to traditional learning in a surgical nursing practicum. The subjects of this study were 102 nursing students in their third year of university who were scheduled to complete a clinical nursing practicum in an operating room or surgical unit. Participants were randomly assigned to either a flipped learning group (n = 51) or a traditional learning group (n = 51) for the 1-week, 45-hour clinical nursing practicum. The flipped-learning group completed independent e-learning lessons on surgical nursing and received a brief orientation prior to the commencement of the practicum, while the traditional-learning group received a face-to-face orientation and on-site instruction. After the completion of the practicum, both groups completed a case study and a conference. The student's self-efficacy, self-leadership, and problem-solving skills in clinical practice were measured both before and after the one-week surgical nursing practicum. Participants' independent goal setting and evaluation of beliefs and assumptions for the subscales of self-leadership and problem-solving skills were compared for the flipped learning group and the traditional learning group. The results showed greater improvement on these indicators for the flipped learning group in comparison to the traditional learning group. The flipped learning method might offer more effective e-learning opportunities in terms of self-leadership and problem-solving than the traditional learning method in surgical nursing practicums.

  2. Medical Students Teaching Medical Students Surgical Skills: The Benefits of Peer-Assisted Learning.

    Science.gov (United States)

    Bennett, Samuel Robert; Morris, Simon Rhys; Mirza, Salman

    2018-04-10

    Teaching surgical skills is a labor intensive process, requiring a high tutor to student ratio for optimal success, and teaching for undergraduate students by consultant surgeons is not always feasible. A surgical skills course was developed, with the aim of assessing the effectiveness of undergraduate surgical peer-assisted learning. Five surgical skills courses were conducted looking at eight domains in surgery, led by foundation year doctors and senior medical students, with a tutor to student ratio of 1:4. Precourse and postcourse questionnaires (Likert scales 0-10) were completed. Mean scores were compared precourse and postcourse. Surgical skills courses took place within clinical skills rooms in the Queen Elizabeth Hospital Birmingham (UK). Seventy students (59 medical, 2 dental, and 9 physician associate students) from a range of academic institutions across the UK completed the course. There was an overall increase in mean scores across all eight domains. Mean improvement score precourse and postcourse in WHO surgical safety checklist (+3.94), scrubbing (+2.99), gowning/gloving (+3.34), knot tying (+5.53), interrupted sutures (+5.89), continuous sutures (+6.53), vertical mattress sutures (+6.46), and local anesthesia (+3.73). Peer-assisted learning is an effective and feasible method for teaching surgical skills in a controlled environment, subsequently improving confidence among healthcare undergraduates. Such teaching may provide the basis for feasibly mass-producing surgical skills courses for healthcare students. Copyright © 2018 Association of Program Directors in Surgery. Published by Elsevier Inc. All rights reserved.

  3. Learning curve of laparoscopy-assisted distal gastrectomy with systemic lymphadenectomy for early gastric cancer

    Institute of Scientific and Technical Information of China (English)

    Min-Chan Kim; Ghap-Joong Jung; Hyung-Ho Kim

    2005-01-01

    AIM: To evaluate the nature of the "learning curve" for laparoscopy-assisted distal gastrectomy (LADG) with systemic lymphadenectomy for early gastric cancer. METHODS: The data of 90 consecutive patients with early gastric cancer who underwent LADG with systemic lymphadenectomy between April 2003 and November 2004 were reviewed. The 90 patients were divided into 9 sequential groups of 10 cases in each group and the average operative time of these 9 groups were determined. Other learning indicators, such as transfusion requirements, conversion rates to open surgery, postoperative complication, time to first flatus, and postoperative hospital stay, were evaluated. RESULTS: After the first 10 LADGs, the operative time reached its first plateau (230-240 min/operation) and then reached a second plateau (<200 min/operation) for the final 30 cases. Although a significant improvement in the operative time was noted after the first 50 cases, there were no significant differences in transfusion requirements, conversion rates to open surgery, postoperative complications, time to first flatus, or postoperative hospital stay between the groups. CONCLUSION: Based on operative time analysis, this study show that experience of 50 cases of LADG with systemic lymphadenectomy for early gastric cancer is required to achieve optimum proficiency.

  4. Contrast agents provide a faster learning curve in dipyridamole stress echocardiography.

    Science.gov (United States)

    Zamorano, Jose; Sánchez, Violeta; Moreno, Raúl; Almería, Carlos; Rodrigo, Jose; Serra, Viviana; Azcona, Luis; Aubele, Adalia; Mataix, Luis; Sánchez-Harguindey, Luis

    2002-12-01

    Interobserver variability is an important limitation of the stress echocardiography and depends on the echocardiographer training. Our aim was to evaluate if the use of contrast agents during dipyridamole stress echocardiography would improve the agreement between an experienced and a non-experienced observer in stress echo and therefore if contrast would affect the learning period of dypyridamole stress echo. Two independent observers without knowledge of any patient data interpreted all stress studies. One observer was an experienced one and the other had experience in echocardiography but not in stress echo. Two observers analysed 87 non-selected and consecutive studies. Out of the 87 studies, 46 were performed without contrast administration, whereas i.v. contrast (2.5 g Levovist by two bolus at rest and at peak stress) was administered in 41. In all cases, second harmonic imaging and stress digitalisation pack was used. The agreement between observers showed a kappa index of 0.58 and 0.83 without and with contrast administration, respectively. The use of contrast agents provides a better agreement in the evaluation of stress echo between an experienced and a non-experienced observer in stress echo. Adding routinely contrast agents could probably reduce the number of exams required for the necessary learning curve in stress echocardiography.

  5. LHC Run 2 – reaching the top of the learning curve

    CERN Multimedia

    2015-01-01

    As the LHC Physics conference gets underway in St Petersburg, it’s a good time to take stock of where things stand with Run 2.    For all those involved with operating the LHC and its experiments in this new energy and intensity regime, 2015 was always going to be a learning curve. And learning we most certainly are. The main objective for this year has always been to set up the machine and experiments for production running at high energy and high intensity in 2016, 17 and 18.  That said, the experiments have all been able to collect quality data at 13 TeV, with the first Run 2 papers and conference presentations being written and delivered this summer. It would be unfair of me, however, to give the impression that it’s all been plain sailing. As well as the highs: smooth recommissioning of the machine, physics getting underway, and a successful transition to 25-nanosecond bunch spacing, we’ve also had our fair share of lows. There have been no sho...

  6. The Sex Difference in Basic Surgical Skills Learning: A Comparative Study.

    Science.gov (United States)

    Lou, Zheng; Yan, Fei-Hu; Zhao, Zhi-Qing; Zhang, Wei; Shui, Xian-Qi; Liu, Jia; Zhuo, Dong-Lan; Li, Li; Yu, En-da

    2016-01-01

    Very little is known of sex-related differences among medical students in the acquisition of basic surgical skills at an undergraduate level. The aim of this study was to investigate the sex differences in basic surgical skills learning and the possible explanations for sex disparities within basic surgical skills education. A didactic description of 10 surgical skills was performed, including knot tying, basic suture I, basic suture II, sterile technique, preoperative preparation, phlebotomy, debridement, laparotomy, cecectomy, and small bowel resection with hand-sewn anastomosis. The students were rated on a 100-point scale for each basic surgical skill. Later during the same semester all the students took the final theoretical examination. A total of 342 (male = 317 and female = 25) medical students participated in a single skills laboratory as part of their third-year medical student clerkship. The mean scores for each of the 10 surgical skills were higher in female group. The difference in sterile technique, preoperative preparation, cecectomy, and small bowel resection with hand-sewn anastomosis reached the significant level. Compared with male medical students, the mean theory examination score was significantly higher in female medical students. Approximately 76% of the (19 of 25) female students expressed their interest in pursuing a surgical career, whereas only 65.5% (207 of 317) male students wanted to be surgical professionals (p = 0.381). Female medical students completed basic surgical skills training more efficiently and passed the theoretical examination with significantly higher scores than male medical students. In the future, studies should be done in other classes in our institution and perhaps other schools to see if these findings are reliable or valid or just a reflection of this 1 sample. Copyright © 2016 Association of Program Directors in Surgery. Published by Elsevier Inc. All rights reserved.

  7. Does Prior Laparoscopic and Open Surgery Experience Have Any Impact on Learning Curve in Transition to Robotic Surgery?

    Directory of Open Access Journals (Sweden)

    Cüneyt Adayener

    2016-12-01

    Full Text Available It has been 15 years since the Food And Drug Administration approved the Da Vinci® robotic surgery system. Robotic applications are being used extensively in urology, particularly in radical prostatectomy. Like all high-tech products, this system also has a high cost and a steep learning curve, therefore, preventing it from becoming widespread. There are various studies on the effect of open surgery or laparoscopy experience on the learning curve of robotic surgery. Analyzing these interactions well will provide valuable information on making the training period of robotic system more efficient.

  8. Learning surgically oriented anatomy in a student-run extracurricular club: an education through recreation initiative.

    Science.gov (United States)

    Ullah, Shahnoor M; Bodrogi, Andrew; Cristea, Octav; Johnson, Marjorie; McAlister, Vivian C

    2012-01-01

    Didactic and laboratory anatomical education have seen significant reductions in the medical school curriculum due, in part, to the current shift from basic science to more clinically based teaching in North American medical schools. In order to increase medical student exposure to anatomy, with clinical applicability, a student-run initiative called surgically oriented anatomy prosectors (SOAP) club was created within the extracurricular program at the Schulich School of Medicine and Dentistry, The University of Western Ontario, London, Canada. SOAP invites surgeons and residents from various surgical specialties to demonstrate, on a cadaver, a surgical procedure of their choosing. During the demonstration, the anatomy, as it relates to the surgical procedure, is discussed. The students then break into smaller groups to examine the relevant anatomy on the cadavers, during which time the discussion is broadened. The group continues the conversation in a social environment with refreshments. SOAP is one of the most popular extracurricular clubs with 65% of first and second year medical students registered as members. The high demand for SOAP, along with the positive participant feedback, may be due to its utilization of the principle of education through recreation, which seeks to provide opportunities for learning seamlessly throughout all facets of life. It also demonstrates the desire, amongst certain medical students, to learn applied anatomy, particularly within a surgical context. Copyright © 2012 American Association of Anatomists.

  9. Learning Curve for Seawater Reverse Osmosis Desalination Plants: Capital Cost Trend of the Past, Present, and Future

    Science.gov (United States)

    Caldera, Upeksha; Breyer, Christian

    2017-12-01

    Seawater reverse osmosis (SWRO) desalination is expected to play a pivotal role in helping to secure future global water supply. While the global reliance on SWRO plants for water security increases, there is no consensus on how the capital costs of SWRO plants will vary in the future. The aim of this paper is to analyze the past trends of the SWRO capital expenditures (capex) as the historic global cumulative online SWRO capacity increases, based on the learning curve concept. The SWRO capex learning curve is found based on 4,237 plants that came online from 1977 to 2015. A learning rate of 15% is determined, implying that the SWRO capex reduced by 15% when the cumulative capacity was doubled. Based on SWRO capacity annual growth rates of 10% and 20%, by 2030, the global average capex of SWRO plants is found to fall to 1,580 USD/(m3/d) and 1,340 USD/(m3/d), respectively. A learning curve for SWRO capital costs has not been presented previously. This research highlights the potential for decrease in SWRO capex with the increase in installation of SWRO plants and the value of the learning curve approach to estimate future SWRO capex.

  10. Efficacy of tension-free vaginal tape compared with transobturator tape in the treatment of stress urinary incontinence in women: analysis of learning curve, perioperative changes of voiding function

    Science.gov (United States)

    2011-01-01

    Background In this study, by comparing TVT surgery and TOT surgery for stress urinary incontinence in women, the characteristics and learning curves of both operative methods were studied. Methods A total of 83 women with stress urinary incontinence treated with tension-free vaginal tape (TVT) (n = 38) or transobturator tape (TOT) (n = 45) at Saiseikai Central Hospital between April 2004 and September 2009 were included. We compare the outcomes and learning curves between TVT surgery and TOT surgery. In statistical analysis, Student's t test, Fisher's exact test, and Mann-Whitney's U test were used. Results The surgical durations were 37.4 ± 15.7 minutes with TVT surgery and 31.0 ± 8.3 minutes with TOT surgery. A longer period of time was required for TVT surgery (p = 0.025). The residual urine at post-operative day 1 was higher in TVT surgery (25.9 ± 44.2 ml) than in TOT surgery (10.6 ± 19.2 ml) (p = 0.0452). The surgical duration of TVT surgery was shortened after the operator had performed 15 operations (p = 0.019). Conclusions In comparison of TVT surgery and TOT surgery, the surgical duration of TVT surgery was longer and the residual urine of TVT surgery was higher at post-operative day 1. Surgical experience could shorten the duration of TVT surgery. PMID:21726448

  11. Efficacy of tension-free vaginal tape compared with transobturator tape in the treatment of stress urinary incontinence in women: analysis of learning curve, perioperative changes of voiding function

    Directory of Open Access Journals (Sweden)

    Kanai Kunimitsu

    2011-07-01

    Full Text Available Abstract Background In this study, by comparing TVT surgery and TOT surgery for stress urinary incontinence in women, the characteristics and learning curves of both operative methods were studied. Methods A total of 83 women with stress urinary incontinence treated with tension-free vaginal tape (TVT (n = 38 or transobturator tape (TOT (n = 45 at Saiseikai Central Hospital between April 2004 and September 2009 were included. We compare the outcomes and learning curves between TVT surgery and TOT surgery. In statistical analysis, Student's t test, Fisher's exact test, and Mann-Whitney's U test were used. Results The surgical durations were 37.4 ± 15.7 minutes with TVT surgery and 31.0 ± 8.3 minutes with TOT surgery. A longer period of time was required for TVT surgery (p = 0.025. The residual urine at post-operative day 1 was higher in TVT surgery (25.9 ± 44.2 ml than in TOT surgery (10.6 ± 19.2 ml (p = 0.0452. The surgical duration of TVT surgery was shortened after the operator had performed 15 operations (p = 0.019. Conclusions In comparison of TVT surgery and TOT surgery, the surgical duration of TVT surgery was longer and the residual urine of TVT surgery was higher at post-operative day 1. Surgical experience could shorten the duration of TVT surgery.

  12. A quality improvement study on avoidable stressors and countermeasures affecting surgical motor performance and learning.

    Science.gov (United States)

    Conrad, Claudius; Konuk, Yusuf; Werner, Paul D; Cao, Caroline G; Warshaw, Andrew L; Rattner, David W; Stangenberg, Lars; Ott, Harald C; Jones, Daniel B; Miller, Diane L; Gee, Denise W

    2012-06-01

    To explore how the 2 most important components of surgical performance--speed and accuracy-are influenced by different forms of stress and what the impact of music is on these factors. On the basis of a recently published pilot study on surgical experts, we designed an experiment examining the effects of auditory stress, mental stress, and music on surgical performance and learning and then correlated the data psychometric measures to the role of music in a novice surgeon's life. Thirty-one surgeons were recruited for a crossover study. Surgeons were randomized to 4 simple standardized tasks to be performed on the SurgicalSIM VR laparoscopic simulator (Medical Education Technologies, Inc, Sarasota, FL), allowing exact tracking of speed and accuracy. Tasks were performed under a variety of conditions, including silence, dichotic music (auditory stress), defined classical music (auditory relaxation), and mental loading (mental arithmetic tasks). Tasks were performed twice to test for memory consolidation and to accommodate for baseline variability. Performance was correlated to the brief Musical Experience Questionnaire (MEQ). Mental loading influences performance with respect to accuracy, speed, and recall more negatively than does auditory stress. Defined classical music might lead to minimally worse performance initially but leads to significantly improved memory consolidation. Furthermore, psychologic testing of the volunteers suggests that surgeons with greater musical commitment, measured by the MEQ, perform worse under the mental loading condition. Mental distraction and auditory stress negatively affect specific components of surgical learning and performance. If used appropriately, classical music may positively affect surgical memory consolidation. It also may be possible to predict surgeons' performance and learning under stress through psychological tests on the role of music in a surgeon's life. Further investigation is necessary to determine the

  13. Validation of the NASA-TLX Score in Ongoing Assessment of Mental Workload During a Laparoscopic Learning Curve in Bariatric Surgery.

    Science.gov (United States)

    Ruiz-Rabelo, Juan Francisco; Navarro-Rodriguez, Elena; Di-Stasi, Leandro Luigi; Diaz-Jimenez, Nelida; Cabrera-Bermon, Juan; Diaz-Iglesias, Carlos; Gomez-Alvarez, Manuel; Briceño-Delgado, Javier

    2015-12-01

    Fatigue and mental workload are directly associated with high-complexity tasks. In general, difficult tasks produce a higher mental workload, leaving little opportunity to deal with new/unexpected events and increasing the likelihood of performance errors. The laparoscopic Roux-en-Y gastric bypass (LRYGB) learning curve is considered to be one of the most difficult to complete in laparoscopic surgery. We wished to validate the National Aeronautics and Space Administration Task Load Index (NASA-TLX) in LRYGB and identify factors that could provoke a higher mental workload for surgeons during the learning curve. A single surgeon was enrolled to undertake 70 consecutive LRYGB procedures with two internal surgeons mentoring the first 35 cases. Patients were consecutive and ranked from case 35 to case 105 according to the date of the surgical procedure ("case rank"). Self-ratings of satisfaction, performance, and fatigue were measured at the end of surgery using a validated NASA-TLX questionnaire. The procedure was recorded for later viewing by two external evaluators. General data for patients and surgical variables were collected prospectively. A moderate correlation between the NASA-TLX score, BMI, operative time, and volumes of blood drainage was observed. There was no correlation between the NASA-TLX score and duration of hospital stay or time of drain removal. BMI ≥50 kg/m(2), male sex, inexperienced first assistant, and type 2 diabetes mellitus were identified as independent predictive factors of a higher NASA-TLX score. The NASA-TLX is a valid tool to gauge mental workload in LRYGB.

  14. Digital tomosynthesis for evaluating metastatic lung nodules: nodule visibility, learning curves, and reading times.

    Science.gov (United States)

    Lee, Kyung Hee; Goo, Jin Mo; Lee, Sang Min; Park, Chang Min; Bahn, Young Eun; Kim, Hyungjin; Song, Yong Sub; Hwang, Eui Jin

    2015-01-01

    To evaluate nodule visibility, learning curves, and reading times for digital tomosynthesis (DT). We included 80 patients who underwent computed tomography (CT) and DT before pulmonary metastasectomy. One experienced chest radiologist annotated all visible nodules on thin-section CT scans using computer-aided detection software. Two radiologists used CT as the reference standard and retrospectively graded the visibility of nodules on DT. Nodule detection performance was evaluated in four sessions of 20 cases each by six readers. After each session, readers were unblinded to the DT images by revealing the true-positive markings and were instructed to self-analyze their own misreads. Receiver-operating-characteristic curves were determined. Among 414 nodules on CT, 53.3% (221/414) were visible on DT. The main reason for not seeing a nodule on DT was small size (93.3%, ≤ 5 mm). DT revealed a substantial number of malignant nodules (84.1%, 143/170). The proportion of malignant nodules among visible nodules on DT was significantly higher (64.7%, 143/221) than that on CT (41.1%, 170/414) (p 0.8, and the average detection rate for malignant nodules was 85% (210/246). The inter-session analysis of the AUC showed no significant differences among the readers, and the detection rate for malignant nodules did not differ across sessions. A slight improvement in reading times was observed. Most malignant nodules > 5 mm were visible on DT. As nodule detection performance was high from the initial session, DT may be readily applicable for radiology residents and board-certified radiologists.

  15. Bypassing the learning curve in permanent seed implants using state-of-the-art technology

    International Nuclear Information System (INIS)

    Beaulieu, Luc; Evans, Dee-Ann Radford; Aubin, Sylviane; Angyalfi, Steven; Husain, Siraj; Kay, Ian; Martin, Andre-Guy; Varfalvy, Nicolas; Vigneault, Eric; Dunscombe, Peter

    2007-01-01

    Purpose: The aim of this study was to demonstrate, based on clinical postplan dose distributions, that technology can be used efficiently to eliminate the learning curve associated with permanent seed implant planning and delivery. Methods and Materials: Dose distributions evaluated 30 days after the implant of the initial 22 consecutive patients treated with permanent seed implants at two institutions were studied. Institution 1 (I1) consisted of a new team, whereas institution 2 (I2) had performed more than 740 preplanned implantations over a 9-year period before the study. Both teams had adopted similar integrated systems based on three-dimensional (3D) transrectal ultrasonography, intraoperative dosimetry, and an automated seed delivery and needle retraction system (FIRST, Nucletron). Procedure time and dose volume histogram parameters such as D90, V100, V150, V200, and others were collected in the operating room and at 30 days postplan. Results: The average target coverage from the intraoperative plan (V100) was 99.4% for I1 and 99.9% for I2. D90, V150, and V200 were 191.4 Gy (196.3 Gy), 75.3% (73.0%), and 37.5% (34.1%) for I1 (I2) respectively. None of these parameters shows a significant difference between institutions. The postplan D90 was 151.2 Gy for I1 and 167.3 Gy for I2, well above the 140 Gy from the Stock et al. analysis, taking into account differences at planning, results in a p value of 0.0676. The procedure time required on average 174.4 min for I1 and 89 min for I2. The time was found to decrease with the increasing number of patients. Conclusion: State-of-the-art technology enables a new brachytherapy team to obtain excellent postplan dose distributions, similar to those achieved by an experienced team with proven long-term clinical results. The cost for bypassing the usual dosimetry learning curve is time, with increasing team experience resulting in shorter treatment times

  16. Self-organizing adaptive map: autonomous learning of curves and surfaces from point samples.

    Science.gov (United States)

    Piastra, Marco

    2013-05-01

    Competitive Hebbian Learning (CHL) (Martinetz, 1993) is a simple and elegant method for estimating the topology of a manifold from point samples. The method has been adopted in a number of self-organizing networks described in the literature and has given rise to related studies in the fields of geometry and computational topology. Recent results from these fields have shown that a faithful reconstruction can be obtained using the CHL method only for curves and surfaces. Within these limitations, these findings constitute a basis for defining a CHL-based, growing self-organizing network that produces a faithful reconstruction of an input manifold. The SOAM (Self-Organizing Adaptive Map) algorithm adapts its local structure autonomously in such a way that it can match the features of the manifold being learned. The adaptation process is driven by the defects arising when the network structure is inadequate, which cause a growth in the density of units. Regions of the network undergo a phase transition and change their behavior whenever a simple, local condition of topological regularity is met. The phase transition is eventually completed across the entire structure and the adaptation process terminates. In specific conditions, the structure thus obtained is homeomorphic to the input manifold. During the adaptation process, the network also has the capability to focus on the acquisition of input point samples in critical regions, with a substantial increase in efficiency. The behavior of the network has been assessed experimentally with typical data sets for surface reconstruction, including suboptimal conditions, e.g. with undersampling and noise. Copyright © 2012 Elsevier Ltd. All rights reserved.

  17. Self-regulated learning strategies used in surgical clerkship and the relationship with clinical achievement.

    Science.gov (United States)

    Turan, Sevgi; Konan, Ali

    2012-01-01

    Self-regulated learning indicates students' skills in controlling their own learning. Self-regulated learning, which a context-specific process, emphasizes autonomy and control. Students gain more autonomy with respect to learning in the clinical years. Examining the self-regulated learning skills of students in this period will provide important clues about the level at which students are ready to use these skills in real-life conditions. The self-regulated learning strategies used by medical students in surgical clerkship were investigated in this study and their relation with clinical achievement was analyzed. The study was conducted during the surgery clerkship of medical students. The participation rate was 94% (309 students). Motivated Strategies for Learning Questionnaire (MSLQ), a case-based examination, Objective Structured Clinical Examination (OSCE), and tutor evaluations for assessing achievement were used. The relationship between the Motivated Strategies for Learning Questionnaire scores of the students and clinical achievement was analyzed with multilinear regression analysis. The findings showed that students use self-regulated learning skills at medium levels during their surgery clerkship. A relationship between these skills and OSCE scores and tutor evaluations was determined. OSCE scores of the students were observed to increase in conjunction with increased self-efficacy levels. However, as students' beliefs regarding control over learning increased, OSCE scores decreased. No significant relationship was defined between self-regulated learning skills and case-based examination scores. We observed that a greater self-efficacy for learning resulted in higher OSCE scores. Conversely, students who believe that learning is a result of their own effort had lower OSCE scores. Copyright © 2012 Association of Program Directors in Surgery. Published by Elsevier Inc. All rights reserved.

  18. How do you tell whether a change in surgical technique leads to a change in outcome?

    Science.gov (United States)

    Vickers, Andrew J; Cronin, Angel M; Masterson, Timothy A; Eastham, James A

    2010-04-01

    Surgeons routinely evaluate and modify their surgical technique to improve patient outcome. It is also common for surgeons to analyze results before and after a change in technique to determine whether the change led to better results. Simple comparison of results before and after surgical modification may be confounded by the surgical learning curve. We developed a statistical method applicable to analyzing before/after surgical studies. We used simulation studies to compare different statistical analyses of before/after studies. We evaluated a simple 2-group comparison of results before and after the modification by the chi-square test and a novel bootstrap method that adjusts for the surgical learning curve. In the presence of the learning curve a simple 2-group comparison almost always showed an ineffective surgical modification to be of benefit. When the surgical modification was harmful, leading to a 10% decrease in the success rate, 2-group comparison nonetheless showed a statistically significant improvement in outcome about 80% of the time. The bootstrap method had only moderate power but did not show that ineffective surgical modifications were beneficial more than would be expected by chance. Simplistic approaches to the analysis of before/after surgical studies may lead to grossly erroneous results under the surgical learning curve. A straightforward alternative statistical method allows investigators to separate the effects of the learning curve from those of the surgical modification. Copyright (c) 2010 American Urological Association Education and Research, Inc. Published by Elsevier Inc. All rights reserved.

  19. Evaluating the Learning Curve for Percutaneous Nephrolithotomy under Total Ultrasound Guidance.

    Directory of Open Access Journals (Sweden)

    Yan Song

    Full Text Available To investigate the learning curve of percutaneous nephrolithotomy under total ultrasound guidance.One hundred and twenty consecutive PCNL operations under total ultrasound guidance performed by a novice surgeon in a tertiary referral center were studied. Operations were analyzed in cohorts of 15 to determine when a plateau was reached for the variables such as operation duration, ultrasound screening time, tract dilation time, stone-free rate and complication rate. Comparison was made with the results of a surgeon who had performed more than 1000 PCNLs. Fluoroscopy was not used at all during procedure.The mean operation time dropped from 82.5 min for the first 15 patients to a mean of 64.7 min for cases 46 through 60(P = 0.047. The ultrasound screening time was a peak of 6.4 min in the first 15 cases, whereas it dropped to a mean of 3.9 min for cases 46 through 60(P = 0.01. The tract dilation time dropped from 4.9 min for the first 15 patients to a mean of 3.8 min for cases 46 through 60(P = 0.036. The senior surgeon had a mean operating time, screening time and tract dilation time equivalent to those of the novice surgeon after 60 cases. There was no significant difference in stone free rate and complication rate.The competence of ultrasound guided PCNL is reached after 60 cases with good stone free rate and without major complications.

  20. The future role of photovoltaics: A learning curve versus portfolio perspective

    International Nuclear Information System (INIS)

    Albrecht, Johan

    2007-01-01

    The current cost disadvantage of photovoltaics (PV) risks to reduce its relevance in climate policy strategies. Depending on the used assumptions, electricity from PV can become competitive between 2015 and 2040. Cost competitiveness is, however, a conditional criterion and as an alternative to the learning curve perspective, the future role of PV in electricity production is assessed from a portfolio theory or Capital Asset Pricing Model perspective. In this analysis, the focus is on the input price risks. Fossil fuel price volatility can strongly reduce the financial return of conventional generating technologies. From a welfare perspective, energy planners should try to minimise this risk by adding risk-neutral or no-risk technologies to their portfolio. With an analysis for the year 2025, we illustrate how the addition of renewable capacity to an existing portfolio can lower total portfolio risk without a significant reduction of profitability. PV then emerges as an attractive technology, especially once the best locations for wind energy are already developed

  1. The future role of photovoltaics: a learning curve versus portfolio perspective

    International Nuclear Information System (INIS)

    Albrecht, J.

    2007-01-01

    The current cost disadvantage of photovoltaics (PV) risks to reduce its relevance in climate policy strategies. Depending on the used assumptions, electricity from PV can become competitive between 2015 and 2040. Cost competitiveness is, however, a conditional criterion and as an alternative to the learning curve perspective, the future role of PV in electricity production is assessed from a portfolio theory or Capital Asset Pricing Model perspective. In this analysis, the focus is on the input price risks. Fossil fuel price volatility can strongly reduce the financial return of conventional generating technologies. From a welfare perspective, energy planners should try to minimise this risk by adding risk-neutral or no-risk technologies to their portfolio. With an analysis for the year 2025, we illustrate how the addition of renewable capacity to an existing portfolio can lower total portfolio risk without a significant reduction of profitability. PV then emerges as an attractive technology, especially once the best locations for wind energy are already developed. (author)

  2. Reliability assessment of a manual-based procedure towards learning curve modeling and fmea analysis

    Directory of Open Access Journals (Sweden)

    Gustavo Rech

    2013-03-01

    Full Text Available Separation procedures in drug Distribution Centers (DC are manual-based activities prone to failures such as shipping exchanged, expired or broken drugs to the customer. Two interventions seem as promising in improving the reliability in the separation procedure: (i selection and allocation of appropriate operators to the procedure, and (ii analysis of potential failure modes incurred by selected operators. This article integrates Learning Curves (LC and FMEA (Failure Mode and Effect Analysis aimed at reducing the occurrence of failures in the manual separation of a drug DC. LCs parameters enable generating an index to identify the recommended operators to perform the procedures. The FMEA is then applied to the separation procedure carried out by the selected operators in order to identify failure modes. It also deployed the traditional FMEA severity index into two sub-indexes related to financial issues and damage to company´s image in order to characterize failures severity. When applied to a drug DC, the proposed method significantly reduced the frequency and severity of failures in the separation procedure.

  3. Fluoroscopy Learning Curve in Hip Arthroscopy-A Single Surgeon's Experience.

    Science.gov (United States)

    Smith, Kevin M; Duplantier, Neil L; Crump, Kimbelyn H; Delgado, Domenica A; Sullivan, Stephanie L; McCulloch, Patrick C; Harris, Joshua D

    2017-10-01

    To determine if (1) absorbed radiation dose and (2) fluoroscopy time decreased with experience over the first 100 cases of a single surgeon's hip arthroscopy practice. Subjects who underwent hip arthroscopy for symptomatic femoroacetabular impingement and labral injury were eligible for analysis. Inclusion criteria included the first 100 subjects who underwent hip arthroscopy by a single surgeon (December 2013 to December 2014). Subject demographics, procedure details, fluoroscopy absorbed dose (milligray [mGy]), and time were recorded. Subjects were categorized by date of surgery to one of 4 possible groups (25 per group). One-way analysis of variance was used to determine if a significant difference in dose (mGy) or time was present between groups. Simple linear regression analysis was performed to determine the relation between case number and both radiation dose and fluoroscopy time. Subjects underwent labral repair (n = 93), cam osteoplasty (n = 90), and pincer acetabuloplasty (n = 65). There was a significant (P arthroscopy practice learning curve. Level IV, therapeutic, retrospective, noncomparative case series. Copyright © 2017 Arthroscopy Association of North America. Published by Elsevier Inc. All rights reserved.

  4. Retroperitoneal laparoscopic nephrectomy: the effect of the learning curve, and concentrating expertise, on operating times.

    Science.gov (United States)

    Skinner, Adrian; Maoate, Kiki; Beasley, Spencer

    2010-05-01

    Laparoscopic nephrectomy is an accepted alternative to open nephrectomy. We analyzed our first 80 procedures of laparoscopic nephrectomy to evaluate the effect of experience and configuration of service on operative times. A retrospective review of 80 consecutive children who underwent retroperitoneal laparoscopic nephrectomy or heminephrectomy during an 11-year period from 1997 at Christchurch Hospital (Christchurch, New Zealand) was conducted. Operative times, in relation to the experience of the surgeon for this procedure, were analyzed. Four surgeons, assisted by an annually rotating trainee registrar, performed the procedure in 26 girls and 54 boys (range, 8 months to 15 years). Operating times ranged from 38 to 225 minutes (mean, 104). The average operative time fell from 105 to 90 minutes. One surgeon performed 40% of the procedures and assisted with a further 55%. The operative times for all surgeons showed a tendency to reduce, but this was not marked. Most procedures were performed by two surgeons working together, although one surgeon was involved in the majority of cases. The lead surgeon is often assisted by a fellow consultant colleague. Operative times were influenced by experience, but not markedly so. The shorter operative times and minimal "learning curve," compared with other reported series, may, in part, be due to the involvement of two surgeons experienced in laparoscopy for the majority of cases.

  5. "Alarm-corrected" ergonomic armrest use could improve learning curves of novices on robotic simulator.

    Science.gov (United States)

    Yang, Kun; Perez, Manuela; Hossu, Gabriela; Hubert, Nicolas; Perrenot, Cyril; Hubert, Jacques

    2017-01-01

    In robotic surgery, the professional ergonomic habit of using an armrest reduces operator fatigue and increases the precision of motion. We designed and validated a pressure surveillance system (PSS) based on force sensors to investigate armrest use. The objective was to evaluate whether adding an alarm to the PSS system could shorten ergonomic training and improve performance. Twenty robot and simulator-naïve participants were recruited and randomized in two groups (A and B). The PSS was installed on a robotic simulator, the dV-Trainer, to detect contact with the armrest. The Group A members completed three tasks on the dV-Trainer without the alarm, making 15 attempts at each task. The Group B members practiced the first two tasks with the alarm and then completed the final tasks without the alarm. The simulator provided an overall score reflecting the trainees' performance. We used the new concept of an "armrest load" score to describe the ergonomic habit of using the armrest. Group B had a significantly higher performance score (p ergonomic errors and accelerated professional ergonomic habit acquisition. The combination of the PSS and alarm is effective in significantly shortening the learning curve in the robotic training process.

  6. Descemet Membrane Endothelial Keratoplasty Learning Curve for Graft Preparation in an Eye Bank Using 645 Donor Corneas.

    Science.gov (United States)

    Parekh, Mohit; Ruzza, Alessandro; Romano, Vito; Favaro, Elisa; Baruzzo, Mattia; Salvalaio, Gianni; Grassetto, Andrea; Ferrari, Stefano; Ponzin, Diego

    2018-03-01

    To investigate the learning curve of Descemet membrane endothelial keratoplasty (DMEK) graft preparation in an eye bank. Four operators prepared 645 DMEK grafts using the stripping technique between 2014 and 2017 at the Veneto Eye Bank Foundation, Italy. Endothelial cell loss (ECL) and tissue wastage were recorded retrospectively after DMEK preparation and correlated with the number of tissues prepared each year by each operator. On average, our operators performed 1 donor preparation a week over the course of this study. Only donors older than 60 years were used in this study, and approximately 10% of donors had diabetes. The Wilcoxon test for paired data and 1-way ANOVA were used for checking statistical significance with the Tukey test as post hoc analysis. P 0.05). There is a learning curve for DMEK graft preparation. ECL and tissue wastage can be reduced with practice and skills. However, each operator may be limited to his or her own learning capability.

  7. Video-Based Surgical Learning: Improving Trainee Education and Preparation for Surgery.

    Science.gov (United States)

    Mota, Paulo; Carvalho, Nuno; Carvalho-Dias, Emanuel; João Costa, Manuel; Correia-Pinto, Jorge; Lima, Estevão

    2017-10-11

    Since the end of the XIX century, teaching of surgery has remained practically unaltered until now. With the dawn of video-assisted laparoscopy, surgery has faced new technical and learning challenges. Due to technological advances, from Internet access to portable electronic devices, the use of online resources is part of the educational armamentarium. In this respect, videos have already proven to be effective and useful, however the best way to benefit from these tools is still not clearly defined. To assess the importance of video-based learning, using an electronic questionnaire applied to residents and specialists of different surgical fields. Importance of video-based learning was assessed in a sample of 141 subjects, using a questionnaire distributed by a GoogleDoc online form. We found that 98.6% of the respondents have already used videos to prepare for surgery. When comparing video sources by formation status, residents were found to use Youtube significantly more often than specialists (p learning is currently a hallmark of surgical preparation among residents and specialists working in Portugal. Based on these findings we believe that the creation of quality and scientifically accurate videos, and subsequent compilation in available video-libraries appears to be the future landscape for video-based learning. Copyright © 2017 Association of Program Directors in Surgery. Published by Elsevier Inc. All rights reserved.

  8. Using a high-fidelity patient simulator with first-year medical students to facilitate learning of cardiovascular function curves.

    Science.gov (United States)

    Harris, David M; Ryan, Kathleen; Rabuck, Cynthia

    2012-09-01

    Students are relying on technology for learning more than ever, and educators need to adapt to facilitate student learning. High-fidelity patient simulators (HFPS) are usually reserved for the clinical years of medical education and are geared to improve clinical decision skills, teamwork, and patient safety. Finding ways to incorporate HFPS into preclinical medical education represents more of a challenge, and there is limited literature regarding its implementation. The main objective of this study was to implement a HFPS activity into a problem-based curriculum to enhance the learning of basic sciences. More specifically, the focus was to aid in student learning of cardiovascular function curves and help students develop heart failure treatment strategies based on basic cardiovascular physiology concepts. Pretests and posttests, along with student surveys, were used to determine student knowledge and perception of learning in two first-year medical school classes. There was an increase of 21% and 22% in the percentage of students achieving correct answers on a posttest compared with their pretest score. The median number of correct questions increased from pretest scores of 2 and 2.5 to posttest scores of 4 and 5 of a possible total of 6 in each respective year. Student survey data showed agreement that the activity aided in learning. This study suggests that a HFPS activity can be implemented during the preclinical years of medical education to address basic science concepts. Additionally, it suggests that student learning of cardiovascular function curves and heart failure strategies are facilitated.

  9. Huang's three-step maneuver shortens the learning curve of laparoscopic spleen-preserving splenic hilar lymphadenectomy.

    Science.gov (United States)

    Huang, Chang-Ming; Huang, Ze-Ning; Zheng, Chao-Hui; Li, Ping; Xie, Jian-Wei; Wang, Jia-Bin; Lin, Jian-Xian; Jun, Lu; Chen, Qi-Yue; Cao, Long-Long; Lin, Mi; Tu, Ru-Hong

    2017-12-01

    The goal of this study was to investigate the difference between the learning curves of different maneuvers in laparoscopic spleen-preserving splenic hilar lymphadenectomy for advanced upper gastric cancer. From January 2010 to April 2014, 53 consecutive patients who underwent laparoscopic spleen-preserving splenic hilar lymphadenectomy via the traditional-step maneuver (group A) and 53 consecutive patients via Huang's three-step maneuver (group B) were retrospectively analyzed. No significant difference in patient characteristics were found between the two groups. The learning curves of groups A and B were divided into phase 1 (1-43 cases and 1-30 cases, respectively) and phase 2 (44-53 cases and 31-53 cases, respectively). Compared with group A, the dissection time, bleeding loss and vascular injury were significantly decreased in group B. No significant differences in short-term outcomes were found between the two maneuvers. The multivariate analysis indicated that the body mass index, short gastric vessels, splenic artery type and maneuver were significantly associated with the dissection time in group B. No significant difference in the survival curve was found between the maneuvers. The learning curve of Huang's three-step maneuver was shorter than that of the traditional-step maneuver, and the former represents an ideal maneuver for laparoscopic spleen-preserving splenic hilar lymphadenectomy.To shorten the learning curve at the beginning of laparoscopic spleen-preserving splenic hilar lymphadenectomy, beginners should beneficially use Huang's three-step maneuver and select patients with advanced upper gastric cancer with a body mass index of less than 25 kg/m 2 and the concentrated type of splenic artery. Copyright © 2017. Published by Elsevier Ltd.

  10. Beliefs and Values about Intra-Operative Teaching and Learning: A Case Study of Surgical Teachers and Trainees

    Science.gov (United States)

    Ong, Caroline C.; Dodds, Agnes; Nestel, Debra

    2016-01-01

    Surgeons require advanced psychomotor skills, critical decision-making and teamwork skills. Much of surgical skills training involve progressive trainee participation in supervised operations where case variability, operating team interaction and environment affect learning, while surgical teachers face the key challenge of ensuring patient…

  11. Utility of Interobserver Agreement Statistics in Establishing Radiology Resident Learning Curves During Self-directed Radiologic Anatomy Training.

    Science.gov (United States)

    Tureli, Derya; Altas, Hilal; Cengic, Ismet; Ekinci, Gazanfer; Baltacioglu, Feyyaz

    2015-10-01

    The aim of the study was to ascertain the learning curves for the radiology residents when first introduced to an anatomic structure in magnetic resonance images (MRI) to which they have not been previously exposed to. The iliolumbar ligament is a good marker for testing learning curves of radiology residents because the ligament is not part of a routine lumbar MRI reporting and has high variability in detection. Four radiologists, three residents without previous training and one mentor, studied standard axial T1- and T2-weighted images of routine lumbar MRI examinations. Radiologists had to define iliolumbar ligament while blinded to each other's findings. Interobserver agreement analyses, namely Cohen and Fleiss κ statistics, were performed for groups of 20 cases to evaluate the self-learning curve of radiology residents. Mean κ values of resident-mentor pairs were 0.431, 0.608, 0.604, 0.826, and 0.963 in the analysis of successive groups (P 0.8). Therefore, a junior radiology resident can obtain enough experience in identifying a rather ambiguous anatomic structure in routine MRI after a brief instruction of a few minutes by a mentor and studying approximately 80 cases by oneself. Implementing this methodology will help radiology educators obtain more concrete ideas on the optimal time and effort required for supported self-directed visual learning processes in resident education. Copyright © 2015 AUR. Published by Elsevier Inc. All rights reserved.

  12. Overall Memory Impairment Identification with Mathematical Modeling of the CVLT-II Learning Curve in Multiple Sclerosis

    Science.gov (United States)

    Stepanov, Igor I.; Abramson, Charles I.; Hoogs, Marietta; Benedict, Ralph H. B.

    2012-01-01

    The CVLT-II provides standardized scores for each of the List A five learning trials, so that the clinician can compare the patient's raw trials 1–5 scores with standardized ones. However, frequently, a patient's raw scores fluctuate making a proper interpretation difficult. The CVLT-II does not offer any other methods for classifying a patient's learning and memory status on the background of the learning curve. The main objective of this research is to illustrate that discriminant analysis provides an accurate assessment of the learning curve, if suitable predictor variables are selected. Normal controls were ninety-eight healthy volunteers (78 females and 20 males). A group of MS patients included 365 patients (266 females and 99 males) with clinically defined multiple sclerosis. We show that the best predictor variables are coefficients B3 and B4 of our mathematical model B3 ∗ exp(−B2  ∗  (X − 1)) + B4  ∗  (1 − exp(−B2  ∗  (X − 1))) because discriminant functions, calculated separately for B3 and B4, allow nearly 100% correct classification. These predictors allow identification of separate impairment of readiness to learn or ability to learn, or both. PMID:22745911

  13. Overall Memory Impairment Identification with Mathematical Modeling of the CVLT-II Learning Curve in Multiple Sclerosis

    Directory of Open Access Journals (Sweden)

    Igor I. Stepanov

    2012-01-01

    Full Text Available The CVLT-II provides standardized scores for each of the List A five learning trials, so that the clinician can compare the patient's raw trials 1–5 scores with standardized ones. However, frequently, a patient's raw scores fluctuate making a proper interpretation difficult. The CVLT-II does not offer any other methods for classifying a patient's learning and memory status on the background of the learning curve. The main objective of this research is to illustrate that discriminant analysis provides an accurate assessment of the learning curve, if suitable predictor variables are selected. Normal controls were ninety-eight healthy volunteers (78 females and 20 males. A group of MS patients included 365 patients (266 females and 99 males with clinically defined multiple sclerosis. We show that the best predictor variables are coefficients 3 and 4 of our mathematical model 3∗exp(−2∗(−1+4∗(1−exp(−2∗(−1 because discriminant functions, calculated separately for 3 and 4, allow nearly 100% correct classification. These predictors allow identification of separate impairment of readiness to learn or ability to learn, or both.

  14. Transforaminal Lumbar Interbody Fusion with Rigid Interspinous Process Fixation: A Learning Curve Analysis of a Surgeon Team's First 74 Cases.

    Science.gov (United States)

    Doherty, Patrick; Welch, Arthur; Tharpe, Jason; Moore, Camille; Ferry, Chris

    2017-05-30

    Studies have shown that a significant learning curve may be associated with adopting minimally invasive transforaminal lumbar interbody fusion (MIS TLIF) with bilateral pedicle screw fixation (BPSF). Accordingly, several hybrid TLIF techniques have been proposed as surrogates to the accepted BPSF technique, asserting that less/fewer fixation(s) or less disruptive fixation may decrease the learning curve while still maintaining the minimally disruptive benefits. TLIF with interspinous process fixation (ISPF) is one such surrogate procedure. However, despite perceived ease of adaptability given the favorable proximity of the spinous processes, no evidence exists demonstrating whether or not the technique may possess its own inherent learning curve. The purpose of this study was to determine whether an intraoperative learning curve for one- and two-level TLIF + ISPF may exist for a single lead surgeon. Seventy-four consecutive patients who received one- or two-Level TLIF with rigid ISPF by a single lead surgeon were retrospectively reviewed. It was the first TLIF + ISPF case series for the lead surgeon. Intraoperative blood loss (EBL), hospitalization length-of-stay (LOS), fluoroscopy time, and postoperative complications were collected. EBL, LOS, and fluoroscopy time were modeled as a function of case number using multiple linear regression methods. A change point was included in each model to allow the trajectory of the outcomes to change during the duration of the case series. These change points were determined using profile likelihood methods. Models were fit using the maximum likelihood estimates for the change points. Age, sex, body mass index (BMI), and the number of treated levels were included as covariates. EBL, LOS, and fluoroscopy time did not significantly differ by age, sex, or BMI (p ≥ 0.12). Only EBL differed significantly by the number of levels (p = 0.026). The case number was not a significant predictor of EBL, LOS, or fluoroscopy time (p ≥ 0

  15. Impact of Three-Dimensional Laparoscopy in a Bariatric Surgery Program: Influence in the Learning Curve.

    Science.gov (United States)

    Padin, Esther Mariño; Santos, Raquel Sánchez; Fernández, Sonia González; Jimenez, Antonia Brox; Fernández, Sergio Estevez; Dacosta, Ester Carrera; Duran, Agata Rial; Artime Rial, Maria; Dominguez Sanchez, Ivan

    2017-10-01

    3D laparoscopy allows the surgeon to regain the sense of depth and improve accuracy. The aim of the study was to assess the impact of 3D in bariatric surgery. A retrospective cohort study was conducted. All our patients who underwent bariatric surgery (sleeve gastrectomy (SG) or gastric bypass (GB)) between 2013 and 2016 were included. We compared 3D laparoscopy cohort and 2D laparoscopy cohort. Variables are as follows: age, sex, DM, hypertension, surgeon experience, and type of intervention. Comparisons of operative time, hospital stay, conversion, complications, reoperation, and exitus are completed. Three hundred twelve consecutive patients were included. 56.9% of patients underwent GB and 43.1% SG. Global complications were 3.2% (fistula 2.5%, hemoperitoneum 0.3%, others 0.4%). One hundred four procedures were performed in the 3D cohort and 208 in the 2D cohort. The 2D cohort and 3D cohort were similar regarding the following: percentage of GB vs SG, age, gender, learning curve, diabetes mellitus 2, hypertension, and sleep apnea. The operating time and hospital stay were significantly reduced in the 3D cohort (144.07 ± 58.07 vs 172.11 ± 76.11 min and 5.12 ± 9.6 vs 7.7 ± 13.2 days. It was the same when we stratified the sample by type of surgery or experience of the surgeon. Complications were reduced in the 3D cohort in the surgeries performed by novice surgeons (10.2 vs 1.8%, p = 0.034). The use of 3D laparoscopy in bariatric surgery in our center has helped reducing the operating time and hospital stay, and improving the safety of the surgery, either in GB or SG, being equally favorable in novice or more experienced surgeons.

  16. What have we learned from quantum field theory in curved space-time

    International Nuclear Information System (INIS)

    Fulling, S.A.

    1984-01-01

    The paper reviews the quantum field theory in curved space-time. Field quantization in gravitational backgrounds; particle creation by black holes; Hawking radiation; quantum field theory in curved space-time; covariant renormalization of the stress-energy-momentum tensor; quantum field theory and quantum gravity; are all discussed. (U.K.)

  17. Are Surgeons Born or Made? A Comparison of Personality Traits and Learning Styles Between Surgical Trainees and Medical Students.

    Science.gov (United States)

    Preece, Ryan A; Cope, Alexandra C

    2016-01-01

    Medical students and surgical trainees differ considerably in both their preferential learning styles and personality traits. This study compares the personality profiles and learning styles of surgical trainees with a cohort of medical students specifically intent on pursuing a surgical career. A cross-sectional study was conducted contrasting surgical trainees with medical students specifying surgical career intent. The 50-item International Personality Item Pool Big-Five Factor Marker (FFM) questionnaire was used to score 5 personality domains (extraversion, conscientiousness, agreeableness, openness to experience, and neuroticism). The 24-item Learning Style Inventory (LSI) Questionnaire was used to determine the preferential learning styles (visual, auditory, or tactile). χ(2) Analysis and independent samples t-test were used to compare LSI and FFM scores, respectively. Surgical trainees from several UK surgical centers were contrasted to undergraduate medical students. A total of 53 medical students who had specifically declared desire to pursue a surgical career and were currently undertaking an undergraduate intercalated degree in surgical sciences were included and contrasted to 37 UK core surgical trainees (postgraduate years 3-4). The LSI questionnaire was completed by 53 students and 37 trainees. FFM questionnaire was completed by 29 medical students and 34 trainees. No significant difference for learning styles preference was detected between the 2 groups (p = 0.139), with the visual modality being the preferred learning style for both students and trainees (69.8% and 54.1%, respectively). Neuroticism was the only personality trait to differ significantly between the 2 groups, with medical students scoring significantly higher than trainees (2.9 vs. 2.6, p = 0.03). Medical students intent on pursuing a surgical career exhibit similar personality traits and learning styles to surgical trainees, with both groups preferring the visual learning modality

  18. Enucleation ratio efficacy might be a better predictor to assess learning curve of holmium laser enucleation of the prostate

    Directory of Open Access Journals (Sweden)

    Chang Wook Jeong

    2012-06-01

    Full Text Available PURPOSE: To appraise the evaluation methods for learning curve and to analyze the non-mentor-aided learning curve and early complications following the holmium laser enucleation of the prostate. MATERIALS AND METHODS:One-hundred and forty (n=140 consecutive patients who underwent HoLEP from July 2008 to July 2010 by a single surgeon (SJO were enrolled. Perioperative clinical variables, including enucleation time, morcellation time, enucleation ratio (enucleation weight/transitional zone volume, enucleation efficacy (enucleated weight/enucleation time, enucleation ratio efficacy (enucleation ratio/enucleation time, and early complication rate were analyzed. RESULTS: Mean prostate volume was 62.7 mL (range 21-162 and preoperative International Prostate Symptom Score (IPSS was 19.0 (4-35. Mean enucleation time and morcellation time were 49.9±23.8 (S.D. min and 11.0±9.7 min, respectively. Median duration of postoperative indwelling catheter was 1 (1-7 day and median hospital stay was 1 (1-6 day. There were a total of 31 surgery-related complications in 27 patients (19.3%, and all were manageable. There was an increasing trend of enucleation efficacy in the first 50 cases. However, enucleation efficacy was linearly correlated with the prostate size (correlation coefficients, R=0.701, p<0.001. But, enucleation ratio efficacy could eliminate the confounding effect of the prostate size (R=-0.101, p=0.233. The plateau of enucleation ratio efficacy was reached around the twenty-fifth case. CONCLUSIONS: Our results demonstrated that the operative learning curve plateau is reached after about 25 cases. We propose that a more appropriate parameter for estimating the operative learning curve is enucleation ratio efficacy, rather than enucleation efficacy.

  19. A Targeted E-Learning Program for Surgical Trainees to Enhance Patient Safety in Preventing Surgical Infection

    Science.gov (United States)

    McHugh, Seamus Mark; Corrigan, Mark; Dimitrov, Borislav; Cowman, Seamus; Tierney, Sean; Humphreys, Hilary; Hill, Arnold

    2010-01-01

    Introduction: Surgical site infection accounts for 20% of all health care-associated infections (HCAIs); however, a program incorporating the education of surgeons has yet to be established across the specialty. Methods: An audit of surgical practice in infection prevention was carried out in Beaumont Hospital from July to November 2009. An…

  20. Surgical training and the European Working Time Directive: The role of informal workplace learning.

    Science.gov (United States)

    Giles, James A

    2010-01-01

    The introduction of European Working Time Directive, limiting doctors' working hours to 48 per week, has caused recent controversy within the profession. The Royal College of Surgeons of England in particular has been one of the loudest critics of the legislation. One of the main concerns is regarding the negative impact on training hours for those embarking on surgical careers. Simulation technology has been suggested as a method to overcome this reduction in hospital training hours, and research suggests that this is a good substitute for operative training in a theatre. However, modern educational theory emphasises the power of informal workplace learning in postgraduate education, and the essential role of experience in training future surgeons. Copyright 2010 Surgical Associates Ltd. Published by Elsevier Ltd. All rights reserved.

  1. Uniportal video-assisted thoracoscopic surgery: safety, efficacy and learning curve during the first 250 cases in Quebec, Canada.

    Science.gov (United States)

    Drevet, Gabrielle; Ugalde Figueroa, Paula

    2016-03-01

    Video-assisted thoracoscopic surgery (VATS) using a single incision (uniportal) may result in better pain control, earlier mobilization and shorter hospital stays. Here, we review the safety and efficiency of our initial experience with uniportal VATS and evaluate our learning curve. We conducted a retrospective review of uniportal VATS using a prospectively maintained departmental database and analyzed patients who had undergone a lung anatomic resection separately from patients who underwent other resections. To assess the learning curve, we compared the first 10 months of the study period with the second 10 months. From January 2014 to August 2015, 250 patients underwent intended uniportal VATS, including 180 lung anatomic resections (72%) and 70 other resections (28%). Lung anatomic resection was successfully completed using uniportal VATS in 153 patients (85%), which comprised all the anatomic segmentectomies (29 patients), 80% (4 of 5) of the pneumonectomies and 82% (120 of 146) of the lobectomies attempted. The majority of lung anatomic resections that required conversion to thoracotomy occurred in the first half of our study period. Seventy patients underwent other uniportal VATS resections. Wedge resections were the most common of these procedures (25 patients, 35.7%). Although 24 of the 70 patients (34%) required the placement of additional ports, none required conversion to thoracotomy. Uniportal VATS was safe and feasible for both standard and complex pulmonary resections. However, when used for pulmonary anatomic resections, uniportal VATS entails a steep learning curve.

  2. Simulation-Based Learning Strategies to Teach Undergraduate Students Basic Surgical Skills: A Systematic Review.

    Science.gov (United States)

    Theodoulou, Iakovos; Nicolaides, Marios; Athanasiou, Thanos; Papalois, Apostolos; Sideris, Michail

    2018-02-16

    We aimed to identify and critically appraise all literature surrounding simulation-based learning (SBL) courses, to assess their relevance as tools for undergraduate surgical education, and create a design framework targeted at standardizing future SBL. We performed a systematic review of the literature using a specific keyword strategy to search at MEDLINE database. Of the 2371 potentially eligible titles, 472 were shortlisted and only 40 explored active interventions in undergraduate medical education. Of those, 20 were conducted in the United States, 9 in Europe and 11 in the rest of the world. Nineteen studies assessed the effectiveness of SBL by comparing students' attributes before and after interventions, 1 study assessed a new tool of surgical assessment and 16 studies evaluated SBL courses from the students' perspectives. Of those 40 studies, 12 used dry laboratory, 7 wet laboratory, 12 mixed, and 9 cadaveric SBL interventions. The extent to which positive results were obtained from dry, wet, mixed, and cadaveric laboratories were 75%, 57%, 92%, and 100%, respectively. Consequently, the SBL design framework was devised, providing a foundation upon which future SBL interventions can be designed such that learning outcomes are optimized. SBL is an important step in surgical education, investing in a safer and more efficient generation of surgeons. Standardization of these efforts can be accelerated with SBL design framework, a comprehensive guide to designing future interventions for basic surgical training at the undergraduate level. Copyright © 2018 Association of Program Directors in Surgery. Published by Elsevier Inc. All rights reserved.

  3. Analysis of the learning curve for peroral endoscopic myotomy for esophageal achalasia: Single-center, two-operator experience.

    Science.gov (United States)

    Lv, Houning; Zhao, Ningning; Zheng, Zhongqing; Wang, Tao; Yang, Fang; Jiang, Xihui; Lin, Lin; Sun, Chao; Wang, Bangmao

    2017-05-01

    Peroral endoscopic myotomy (POEM) has emerged as an advanced technique for the treatment of achalasia, and defining the learning curve is mandatory. From August 2011 to June 2014, two operators in our institution (A&B) carried out POEM on 35 and 33 consecutive patients, respectively. Moving average and cumulative sum (CUSUM) methods were used to analyze the POEM learning curve for corrected operative time (cOT), referring to duration of per centimeter myotomy. Additionally, perioperative outcomes were compared among distinct learning curve phases. Using the moving average method, cOT reached a plateau at the 29th case and at the 24th case for operators A and B, respectively. CUSUM analysis identified three phases: initial learning period (Phase 1), efficiency period (Phase 2) and mastery period (Phase 3). The relatively smooth state in the CUSUM graph occurred at the 26th case and at the 24th case for operators A and B, respectively. Mean cOT of distinct phases for operator A were 8.32, 5.20 and 3.97 min, whereas they were 5.99, 3.06 and 3.75 min for operator B, respectively. Eckardt score and lower esophageal sphincter pressure significantly decreased during the 1-year follow-up period. Data were comparable regarding patient characteristics and perioperative outcomes. This single-center study demonstrated that expert endoscopists with experience in esophageal endoscopic submucosal dissection reached a plateau in learning of POEM after approximately 25 cases. © 2016 Japan Gastroenterological Endoscopy Society.

  4. Training anesthesiology residents in providing anesthesia for awake craniotomy: learning curves and estimate of needed case load.

    Science.gov (United States)

    Bilotta, Federico; Titi, Luca; Lanni, Fabiana; Stazi, Elisabetta; Rosa, Giovanni

    2013-08-01

    To measure the learning curves of residents in anesthesiology in providing anesthesia for awake craniotomy, and to estimate the case load needed to achieve a "good-excellent" level of competence. Prospective study. Operating room of a university hospital. 7 volunteer residents in anesthesiology. Residents underwent a dedicated training program of clinical characteristics of anesthesia for awake craniotomy. The program was divided into three tasks: local anesthesia, sedation-analgesia, and intraoperative hemodynamic management. The learning curve for each resident for each task was recorded over 10 procedures. Quantitative assessment of the individual's ability was based on the resident's self-assessment score and the attending anesthesiologist's judgment, and rated by modified 12 mm Likert scale, reported ability score visual analog scale (VAS). This ability VAS score ranged from 1 to 12 (ie, very poor, mild, moderate, sufficient, good, excellent). The number of requests for advice also was recorded (ie, resident requests for practical help and theoretical notions to accomplish the procedures). Each task had a specific learning rate; the number of procedures necessary to achieve "good-excellent" ability with confidence, as determined by the recorded results, were 10 procedures for local anesthesia, 15 to 25 procedures for sedation-analgesia, and 20 to 30 procedures for intraoperative hemodynamic management. Awake craniotomy is an approach used increasingly in neuroanesthesia. A dedicated training program based on learning specific tasks and building confidence with essential features provides "good-excellent" ability. © 2013 Elsevier Inc. All rights reserved.

  5. The effect of surgical and psychological stress on learning and memory function in aged C57BL/6 mice.

    Science.gov (United States)

    Zhang, C; Li, C; Xu, Z; Zhao, S; Li, P; Cao, J; Mi, W

    2016-04-21

    Postoperative cognitive dysfunction (POCD) is an important complication following major surgery and general anesthesia in older patients. However, the etiology of POCD remains largely to be determined. It is unknown how surgical stress and psychological stress affect the postoperative learning and memory function in geriatric patients. We therefore established a pre-clinical model in aged C57BL/6 mice and aimed to investigate the effects of surgical stress and psychological stress on learning and memory function and the possible roles of the protein kinase B/mammalian target of rapamycin (AKT/mTOR) pathway. The surgical stress was induced by abdominal surgery under local anesthesia, and the psychological stress was induced by a communication box. Cognitive functions and markers of the AKT/mTOR pathway were assessed at 1, 3 and 7 days following the stress. The impairments of learning and memory function existed for up to 7 days following surgical stress and surgical stress plus psychological stress, whereas the psychological stress did not affect the cognitive function alone or combined with surgical stress. Analysis of brain tissue revealed a significant involvement of the AKT/mTOR pathway in the impairment of cognition. These data suggested that surgical stress could induce cognitive impairment in aged mice and perioperative psychological stress is not a constitutive factor of POCD. The AKT/mTOR pathway is likely involved as one of the underlying mechanisms of the development of POCD. Copyright © 2016 IBRO. Published by Elsevier Ltd. All rights reserved.

  6. A variation reduction allocation model for quality improvement to minimize investment and quality costs by considering suppliers’ learning curve

    Science.gov (United States)

    Rosyidi, C. N.; Jauhari, WA; Suhardi, B.; Hamada, K.

    2016-02-01

    Quality improvement must be performed in a company to maintain its product competitiveness in the market. The goal of such improvement is to increase the customer satisfaction and the profitability of the company. In current practice, a company needs several suppliers to provide the components in assembly process of a final product. Hence quality improvement of the final product must involve the suppliers. In this paper, an optimization model to allocate the variance reduction is developed. Variation reduction is an important term in quality improvement for both manufacturer and suppliers. To improve suppliers’ components quality, the manufacturer must invest an amount of their financial resources in learning process of the suppliers. The objective function of the model is to minimize the total cost consists of investment cost, and quality costs for both internal and external quality costs. The Learning curve will determine how the employee of the suppliers will respond to the learning processes in reducing the variance of the component.

  7. Self-directed Learning in Otolaryngology Residents' Preparation for Surgical Cases.

    Science.gov (United States)

    Jabbour, Jad; Bakeman, Anna; Robey, Thomas; Jabbour, Noel

    2017-04-01

    To characterize the nature of surgical preparation among otolaryngology residents nationwide, determine the self-rated effectiveness and efficiency of case preparation practices, and identify potential means for educational improvement. A survey examining the study objectives was developed and distributed to otolaryngology residents nationwide. Survey response data were submitted to descriptive analysis and comparative analyses between junior and senior residents. Literature regarding case preparation among otolaryngology residents was reviewed. Among 108 resident respondents, the most commonly used resources included textbooks (86.1%), surgical education websites (74.1%), and surgical atlases (66.7%). Time was the primary limitation (cited by 84.3%) and convenience the predominant factor influencing resource selection (92.5%). On a 5-point Likert scale, mean scores regarding effectiveness and efficiency of case preparation were 3.53 ± 0.68 and 3.19 ± 0.88, respectively. Senior residents compared to junior residents were more likely to rate their preparation as effective (3.75 ± 0.54 vs 3.40 ± 0.72, P = .008) and efficient (3.45 ± 0.85 vs 3.03 ± 0.86, P = .02). Otolaryngology residents do not consistently rate their case preparation as effective or efficient. While there appears to be progress in self-directed learning throughout residency, room for improvement remains, with potential avenues for such improvement explored here.

  8. Provincial carbon intensity abatement potential estimation in China: A PSO–GA-optimized multi-factor environmental learning curve method

    International Nuclear Information System (INIS)

    Yu, Shiwei; Zhang, Junjie; Zheng, Shuhong; Sun, Han

    2015-01-01

    This study aims to estimate carbon intensity abatement potential in China at the regional level by proposing a particle swarm optimization–genetic algorithm (PSO–GA) multivariate environmental learning curve estimation method. The model uses two independent variables, namely, per capita gross domestic product (GDP) and the proportion of the tertiary industry in GDP, to construct carbon intensity learning curves (CILCs), i.e., CO 2 emissions per unit of GDP, of 30 provinces in China. Instead of the traditional ordinary least squares (OLS) method, a PSO–GA intelligent optimization algorithm is used to optimize the coefficients of a learning curve. The carbon intensity abatement potentials of the 30 Chinese provinces are estimated via PSO–GA under the business-as-usual scenario. The estimation reveals the following results. (1) For most provinces, the abatement potentials from improving a unit of the proportion of the tertiary industry in GDP are higher than the potentials from raising a unit of per capita GDP. (2) The average potential of the 30 provinces in 2020 will be 37.6% based on the emission's level of 2005. The potentials of Jiangsu, Tianjin, Shandong, Beijing, and Heilongjiang are over 60%. Ningxia is the only province without intensity abatement potential. (3) The total carbon intensity in China weighted by the GDP shares of the 30 provinces will decline by 39.4% in 2020 compared with that in 2005. This intensity cannot achieve the 40%–45% carbon intensity reduction target set by the Chinese government. Additional mitigation policies should be developed to uncover the potentials of Ningxia and Inner Mongolia. In addition, the simulation accuracy of the CILCs optimized by PSO–GA is higher than that of the CILCs optimized by the traditional OLS method. - Highlights: • A PSO–GA-optimized multi-factor environmental learning curve method is proposed. • The carbon intensity abatement potentials of the 30 Chinese provinces are estimated by

  9. Does rating the operation videos with a checklist score improve the effect of E-learning for bariatric surgical training? Study protocol for a randomized controlled trial.

    Science.gov (United States)

    De La Garza, Javier Rodrigo; Kowalewski, Karl-Friedrich; Friedrich, Mirco; Schmidt, Mona Wanda; Bruckner, Thomas; Kenngott, Hannes Götz; Fischer, Lars; Müller-Stich, Beat-Peter; Nickel, Felix

    2017-03-21

    Laparoscopic training has become an important part of surgical education. Laparoscopic Roux-en-Y gastric bypass (RYGB) is the most common bariatric procedure performed. Surgeons must be well trained prior to operating on a patient. Multimodality training is vital for bariatric surgery. E-learning with videos is a standard approach for training. The present study investigates whether scoring the operation videos with performance checklists improves learning effects and transfer to a simulated operation. This is a monocentric, two-arm, randomized controlled trial. The trainees are medical students from the University of Heidelberg in their clinical years with no prior laparoscopic experience. After a laparoscopic basic virtual reality (VR) training, 80 students are randomized into one of two arms in a 1:1 ratio to the checklist group (group A) and control group without a checklist (group B). After all students are given an introduction of the training center, VR trainer and laparoscopic instruments, they start with E-learning while watching explanations and videos of RYGB. Only group A will perform ratings with a modified Bariatric Objective Structured Assessment of Technical Skill (BOSATS) scale checklist for all videos watched. Group B watches the same videos without rating. Both groups will then perform an RYGB in the VR trainer as a primary endpoint and small bowel suturing as an additional test in the box trainer for evaluation. This study aims to assess if E-learning and rating bariatric surgical videos with a modified BOSATS checklist will improve the learning curve for medical students in an RYGB VR performance. This study may help in future laparoscopic and bariatric training courses. German Clinical Trials Register, DRKS00010493 . Registered on 20 May 2016.

  10. Education Isn’t Education: The Creativity Response or How to Improve the Learning Curve in Our Society

    Directory of Open Access Journals (Sweden)

    Stefan Brunnhuber

    2017-06-01

    Full Text Available Despite rising expenditure and general enrolment rates on a global level, educational output is stagnating, if not declining. There is increasing empirical evidence that we need a completely different approach to enhancing the learning curve; this holds true for early childhood, primary education, secondary education and higher education. Most existing educational programs do not tap into the full creative potential of our minds and our brains and often lead to suboptimal outcomes both for the individual and for society as a whole. Findings in clinical psychology, neurobiology and social psychology are not sufficiently considered when setting up appropriate educational programs. It is not the cognitive part of the curriculum that makes a difference, but rather the non-cognitive features (including stress management, impulse control, self-regulation, emotional attachment etc. that improve creativity. A ‘six-pack’ of features, including exercise, nutrition, social contact, mindfulness-based practices, sleeping well, and multi-sensory learning, is introduced as part of a ‘creativity response’. They are simple, affordable, evidence-based and efficient strategies that can be implemented promptly without additional costs, increasing our learning curve.

  11. The learning curve of the three-port two-instrument complete thoracoscopic lobectomy for lung cancer—A feasible technique worthy of popularization

    Directory of Open Access Journals (Sweden)

    Yu-Jen Cheng

    2015-07-01

    Conclusion: Three-port complete thoracoscopic lobectomy with the two-instrument technique is feasible for lung cancer treatment. The length of the learning curve consisted of 28 cases. This TPTI technique should be popularized.

  12. Learning Curve Analyses in Neurodevelopmental Disorders: Are Children with Autism Spectrum Disorder Truly Visual Learners?

    Science.gov (United States)

    Erdodi, Laszlo; Lajiness-O'Neill, Renee; Schmitt, Thomas A.

    2013-01-01

    Visual and auditory verbal learning using a selective reminding format was studied in a mixed clinical sample of children with autism spectrum disorder (ASD) (n = 42), attention-deficit hyperactivity disorder (n = 83), velocardiofacial syndrome (n = 17) and neurotypicals (n = 38) using the Test of Memory and Learning to (1) more thoroughly…

  13. Analysis of the learning curve for pre-cut corneal specimens in preparation for lamellar transplantation: a prospective, single-centre, consecutive case series prepared at the Lions New South Wales Eye Bank.

    Science.gov (United States)

    Martin, Aifric Isabel; Devasahayam, Rajnesh; Hodge, Christopher; Cooper, Simon; Sutton, Gerard L

    2017-09-01

    This study is the first paper to establish a learning curve by a single technician. Preparation of pre-cut corneal endothelial grafts commenced at Lions New South Wales Eye Bank in December 2014. The primary objective of this study was to review the safety and reliability of the preparation method during the first year of production. This is a hospital-based, prospective case series. There were 234 consecutive donor corneal lenticules. Donor lenticules were prepared by a single operator using a linear cutting microkeratome. Immediately prior to cutting, central corneal thickness values were recorded. Measurements of the corneal bed were taken immediately following lenticule preparation. Outcomes were separated by blade sizes, and intended thickness was compared to actual thickness for each setting. Early specimens were compared to later ones to assess for a learning curve within the technique. The main parameter measured is the mean difference from intended lamellar cut thickness. The mean final cut thickness was 122.36 ± 20.35 μm, and the mean difference from intended cut was 30.17 ± 37.45 μm. No significant difference was found between results achieved with early specimens versus those achieved with later specimens (P = 0.425). Thin, reproducible endothelial grafts can routinely be produced by trained technicians at their respective eye banks without significant concerns for an extended learning curve. This service can reduce perioperative surgical complexity, required surgical paraphernalia and theatre times. The consistent preparation of single-pass, ultrathin pre-cut corneas may have additional advantages for surgeons seeking to introduce lamellar techniques. © 2017 Royal Australian and New Zealand College of Ophthalmologists.

  14. Diffusion of robotics into clinical practice in the United States: process, patient safety, learning curves, and the public health.

    Science.gov (United States)

    Mirheydar, Hossein S; Parsons, J Kellogg

    2013-06-01

    Robotic technology disseminated into urological practice without robust comparative effectiveness data. To review the diffusion of robotic surgery into urological practice. We performed a comprehensive literature review focusing on diffusion patterns, patient safety, learning curves, and comparative costs for robotic radical prostatectomy, partial nephrectomy, and radical cystectomy. Robotic urologic surgery diffused in patterns typical of novel technology spreading among practicing surgeons. Robust evidence-based data comparing outcomes of robotic to open surgery were sparse. Although initial Level 3 evidence for robotic prostatectomy observed complication outcomes similar to open prostatectomy, subsequent population-based Level 2 evidence noted an increased prevalence of adverse patient safety events and genitourinary complications among robotic patients during the early years of diffusion. Level 2 evidence indicated comparable to improved patient safety outcomes for robotic compared to open partial nephrectomy and cystectomy. Learning curve recommendations for robotic urologic surgery have drawn exclusively on Level 4 evidence and subjective, non-validated metrics. The minimum number of cases required to achieve competency for robotic prostatectomy has increased to unrealistically high levels. Most comparative cost-analyses have demonstrated that robotic surgery is significantly more expensive than open or laparoscopic surgery. Evidence-based data are limited but suggest an increased prevalence of adverse patient safety events for robotic prostatectomy early in the national diffusion period. Learning curves for robotic urologic surgery are subjective and based on non-validated metrics. The urological community should develop rigorous, evidence-based processes by which future technological innovations may diffuse in an organized and safe manner.

  15. An application of the learning curve-cumulative summation test to evaluate training for endotracheal intubation in emergency medicine.

    Science.gov (United States)

    Je, Sangmo; Cho, Youngsuk; Choi, Hyuk Joong; Kang, Boseung; Lim, Taeho; Kang, Hyunggoo

    2015-04-01

    The learning curve-cumulative summation (LC-CUSUM) test allows for quantitative and individual assessments of the learning process. In this study, we evaluated the process of skill acquisition for performing endotracheal intubation (ETI) in three emergency medicine (EM) residents over a 2 year period in their first 2 years of their EM residency. We evaluated 342 ETI cases performed by three EM residents using the LC-CUSUM test according to their rate of success or failure of ETI. A 90% success rate (SR) was chosen to define adequate performance and an SR of 80% was considered inadequate. After the learning phase, the standard CUSUM test was applied to ensure that performance was maintained. The mean number of ETI cases required to reach the predefined level of performance was 74.7 (95% CI 62.0 to 87.3). CUSUM tests confirmed that performance was maintained after the learning phase. By using the LC-CUSUM test, we were able to quantitatively monitor the acquisition of the skill of ETI by EM residents. The LC-CUSUM could be useful for monitoring the learning process for the training of airway management in the practice of EM. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.

  16. Learning curve for hysteroscopic sterilisation: lessons from the first 80 cases.

    Science.gov (United States)

    Rosen, David M B

    2004-02-01

    The present report looks at the first 80 patients of Essure sterilisation performed by a surgeon with experience in operative hysteroscopy. The results show that the procedure is well tolerated under local anaesthesia with or without sedation, and that devices can be successfully placed in 90% of cases. Surgical time is reduced with increased experience, and successful placement increased by improving visibility within the endometrial cavity (cycle timing).

  17. Assessment of performance measures and learning curves for use of a virtual-reality ultrasound simulator in transvaginal ultrasound examination

    DEFF Research Database (Denmark)

    Madsen, M E; Konge, L; Nørgaard, L N

    2014-01-01

    OBJECTIVE: To assess the validity and reliability of performance measures, develop credible performance standards and explore learning curves for a virtual-reality simulator designed for transvaginal gynecological ultrasound examination. METHODS: A group of 16 ultrasound novices, along with a group......-6), corresponding to an average of 219 min (range, 150-251 min) of training. The test/retest reliability was high, with an intraclass correlation coefficient of 0.93. CONCLUSIONS: Competence in the performance of gynecological ultrasound examination can be assessed in a valid and reliable way using virtual-reality...

  18. Performance of medical students on a virtual reality simulator for knee arthroscopy: an analysis of learning curves and predictors of performance.

    Science.gov (United States)

    Rahm, Stefan; Wieser, Karl; Wicki, Ilhui; Holenstein, Livia; Fucentese, Sandro F; Gerber, Christian

    2016-03-25

    Ethical concerns for surgical training on patients, limited working hours with fewer cases per trainee and the potential to better select talented persons for arthroscopic surgery raise the interest in simulator training for arthroscopic surgery. It was the purpose of this study to analyze learning curves of novices using a knee arthroscopy simulator and to correlate their performance with potentially predictive factors. Twenty medical students completed visuospatial tests and were then subjected to a simulator training program of eight 30 min sessions. Their test results were quantitatively correlated with their simulator performance at initiation, during and at the end of the program. The mean arthroscopic performance score (z-score in points) at the eight test sessions were 1. -35 (range, -126 to -5) points, 2. -16 (range, -30 to -2), 3. -11 (range, -35 to 4), 4. -3 (range, -16 to 5), 5. -2 (range, -28 to 7), 6. 1 (range, -18 to 8), 7. 2 (range, -9 to 8), 8. 2 (range, -4 to 7). Scores improved significantly from sessions 1 to 2 (p = 0.001), 2 to 3 (p = 0.052) and 3 to 4 (p = 0.001) but not thereafter. None of the investigated parameters predicted performance or development of arthroscopic performance. Novices improve significantly within four 30 min test virtual arthroscopy knee simulator training but not thereafter within the setting studied. No factors, predicting talent or speed and magnitude of improvement of skills could be identified.

  19. Learning Curve in a Western Training Center of the Circumferential En Bloc Esophageal Endoscopic Submucosal Dissection in an In Vivo Animal Model

    Directory of Open Access Journals (Sweden)

    Miguel A. Tanimoto

    2011-01-01

    Full Text Available Aim. Evaluate the feasibility to overcome the learning curve in a western training center of the en bloc circumferential esophageal (ECE- ESD in an in vivo animal model. Methods. ECE-ESD was performed on ten canine models under general anesthesia on artificial lesions at the esophagus marked with coagulation points. After the ESD each canine model was euthanized and surgical resection of the esophagus and stomach was carried out according to “the Principles of Humane Experimental Technique, Russel and Burch.” The specimen was fixed with needles on cork submerged in formalin with the esophagus and stomach then delivered to the pathology department to be analyzed. Results. ECE-ESD was completed without complications in the last 3/10 animal models. Mean duration for the procedures was 192±35 minutes (range 140–235 minutes. All the procedures were done at the animal lab surgery room with cardio pulmonary monitoring and artificial ventilation by staff surgery members and a staff member of the Gastroenterology department trained during 1999–2001 at the Fujigaoka hospital of the Showa U. in Yokohama, Japan, length (range 15–18 mm and 51±6.99 width (range 40–60 mm. Conclusion. ECE-ESD training is feasible in canine models for postgraduate endoscopy fellows.

  20. Learning curves of theta/beta neurofeedback in children with ADHD

    NARCIS (Netherlands)

    Janssen, T.W.P.; Bink, M.; Weeda, W.D.; Gelade, K.N.; Van, Mourik R.; Maras, A.; Oosterlaan, J.

    2017-01-01

    Neurofeedback is widely applied as non-pharmacological intervention aimed at reducing symptoms of ADHD, even though efficacy has not been unequivocally established. Neuronal changes during the neurofeedback intervention that resemble learning can provide crucial evidence for the feasibility and

  1. The learning curve for laparoscopic colectomy in colorectal cancer at a new regional hospital

    Directory of Open Access Journals (Sweden)

    Kuei-Yen Tsai

    2016-01-01

    Conclusion: Laparoscopic colectomy for colorectal cancer in a new regional hospital is feasible and safe. It does not need additional time for learning. Laparoscopic sigmoidectomy can be considered as the initial surgery for a trainee.

  2. Learning Curves: Making Quality Online Health Information Available at a Fitness Center

    OpenAIRE

    Dobbins, Montie T.; Tarver, Talicia; Adams, Mararia; Jones, Dixie A.

    2012-01-01

    Meeting consumer health information needs can be a challenge. Research suggests that women seek health information from a variety of resources, including the Internet. In an effort to make women aware of reliable health information sources, the Louisiana State University Health Sciences Center – Shreveport Medical Library engaged in a partnership with a franchise location of Curves International, Inc. This article will discuss the project, its goals and its challenges.

  3. Short-radius horizontal well re-entry learning curve: prize, cost and operational experience

    Energy Technology Data Exchange (ETDEWEB)

    Boote, K. [Ocelot Energy Inc., Calgary, AB (Canada); MacDonald, R. [Lauron Engineering Ltd, Calgary, AB (Canada)

    1997-12-01

    Six mature vertical wells in Alberta belonging to Ocelot Energy Inc., were reentered and drilled horizontally. Experiences gained, the modifications made to the drilling program and the rewards in the form of incremental oil, were discussed. Details of pre- and post-performance, operational experiences with exiting the casing, building the curve, overbalance versus underbalanced drilling, motors, directional equipment, setting liners, remedial workovers and the cost of the operation were part of the discussion.

  4. Ensemble Learning Method for Outlier Detection and its Application to Astronomical Light Curves

    Science.gov (United States)

    Nun, Isadora; Protopapas, Pavlos; Sim, Brandon; Chen, Wesley

    2016-09-01

    Outlier detection is necessary for automated data analysis, with specific applications spanning almost every domain from financial markets to epidemiology to fraud detection. We introduce a novel mixture of the experts outlier detection model, which uses a dynamically trained, weighted network of five distinct outlier detection methods. After dimensionality reduction, individual outlier detection methods score each data point for “outlierness” in this new feature space. Our model then uses dynamically trained parameters to weigh the scores of each method, allowing for a finalized outlier score. We find that the mixture of experts model performs, on average, better than any single expert model in identifying both artificially and manually picked outliers. This mixture model is applied to a data set of astronomical light curves, after dimensionality reduction via time series feature extraction. Our model was tested using three fields from the MACHO catalog and generated a list of anomalous candidates. We confirm that the outliers detected using this method belong to rare classes, like Novae, He-burning, and red giant stars; other outlier light curves identified have no available information associated with them. To elucidate their nature, we created a website containing the light-curve data and information about these objects. Users can attempt to classify the light curves, give conjectures about their identities, and sign up for follow up messages about the progress made on identifying these objects. This user submitted data can be used further train of our mixture of experts model. Our code is publicly available to all who are interested.

  5. Learning Curves: Making Quality Online Health Information Available at a Fitness Center.

    Science.gov (United States)

    Dobbins, Montie T; Tarver, Talicia; Adams, Mararia; Jones, Dixie A

    2012-01-01

    Meeting consumer health information needs can be a challenge. Research suggests that women seek health information from a variety of resources, including the Internet. In an effort to make women aware of reliable health information sources, the Louisiana State University Health Sciences Center - Shreveport Medical Library engaged in a partnership with a franchise location of Curves International, Inc. This article will discuss the project, its goals and its challenges.

  6. The Impact of Learning Curve Model Selection and Criteria for Cost Estimation Accuracy in the DoD

    Science.gov (United States)

    2016-04-30

    different in the future due to machines” • Heightened scrutiny of cost estimates • Budget Control Act of 2011 seeks to reduce federal deficit ...qÜáêíÉÉåíÜ=^ååì~ä= ^Åèìáëáíáçå=oÉëÉ~êÅÜ= póãéçëáìã= qÜìêëÇ~ó=pÉëëáçåë= sçäìãÉ=ff= = The Impact of Learning Curve Model Selection and Criteria for Cost...Assistant Division Director, Institute for Defense Analyses Bruce Harmon, Research Staff Member, Institute for Defense Analyses The Impact of Learning

  7. The integration of computerised accounting in the accounting curriculum as an educational learning curve for students entering the business world

    Directory of Open Access Journals (Sweden)

    Elmarie Papageorgiou

    2014-06-01

    Full Text Available At universities, educating students on real-life practices is one of the key drivers in a changing academic environment. Academic institutions encourage the study of the learning environment and ensure that appropriate strategies are in place for educating students. A first-year Accounting I student stated the importance of computerised accounting: ‘Computerised accounting is used in the workplace and therefore using it in varsity, grants students a view on how things will be after completion of their respective degrees.’ Accordingly, the purpose of this study was to empirically investigate the perceived acquisition of information technology (IT knowledge and determine the skills required for students to convert the knowledge gained into actions as a learning curve for accounting students entering the business world. The results indicated that students’ knowledge of Accounting I increased with the integration of computerised Accounting in the Accounting I Curriculum.

  8. Big Data and Machine Learning in Plastic Surgery: A New Frontier in Surgical Innovation.

    Science.gov (United States)

    Kanevsky, Jonathan; Corban, Jason; Gaster, Richard; Kanevsky, Ari; Lin, Samuel; Gilardino, Mirko

    2016-05-01

    Medical decision-making is increasingly based on quantifiable data. From the moment patients come into contact with the health care system, their entire medical history is recorded electronically. Whether a patient is in the operating room or on the hospital ward, technological advancement has facilitated the expedient and reliable measurement of clinically relevant health metrics, all in an effort to guide care and ensure the best possible clinical outcomes. However, as the volume and complexity of biomedical data grow, it becomes challenging to effectively process "big data" using conventional techniques. Physicians and scientists must be prepared to look beyond classic methods of data processing to extract clinically relevant information. The purpose of this article is to introduce the modern plastic surgeon to machine learning and computational interpretation of large data sets. What is machine learning? Machine learning, a subfield of artificial intelligence, can address clinically relevant problems in several domains of plastic surgery, including burn surgery; microsurgery; and craniofacial, peripheral nerve, and aesthetic surgery. This article provides a brief introduction to current research and suggests future projects that will allow plastic surgeons to explore this new frontier of surgical science.

  9. Laparoscopic colorectal surgery in learning curve: Role of implementation of a standardized technique and recovery protocol. A cohort study

    Science.gov (United States)

    Luglio, Gaetano; De Palma, Giovanni Domenico; Tarquini, Rachele; Giglio, Mariano Cesare; Sollazzo, Viviana; Esposito, Emanuela; Spadarella, Emanuela; Peltrini, Roberto; Liccardo, Filomena; Bucci, Luigi

    2015-01-01

    Background Despite the proven benefits, laparoscopic colorectal surgery is still under utilized among surgeons. A steep learning is one of the causes of its limited adoption. Aim of the study is to determine the feasibility and morbidity rate after laparoscopic colorectal surgery in a single institution, “learning curve” experience, implementing a well standardized operative technique and recovery protocol. Methods The first 50 patients treated laparoscopically were included. All the procedures were performed by a trainee surgeon, supervised by a consultant surgeon, according to the principle of complete mesocolic excision with central vascular ligation or TME. Patients underwent a fast track recovery programme. Recovery parameters, short-term outcomes, morbidity and mortality have been assessed. Results Type of resections: 20 left side resections, 8 right side resections, 14 low anterior resection/TME, 5 total colectomy and IRA, 3 total panproctocolectomy and pouch. Mean operative time: 227 min; mean number of lymph-nodes: 18.7. Conversion rate: 8%. Mean time to flatus: 1.3 days; Mean time to solid stool: 2.3 days. Mean length of hospital stay: 7.2 days. Overall morbidity: 24%; major morbidity (Dindo–Clavien III): 4%. No anastomotic leak, no mortality, no 30-days readmission. Conclusion Proper laparoscopic colorectal surgery is safe and leads to excellent results in terms of recovery and short term outcomes, even in a learning curve setting. Key factors for better outcomes and shortening the learning curve seem to be the adoption of a standardized technique and training model along with the strict supervision of an expert colorectal surgeon. PMID:25859386

  10. Effects of technological learning and uranium price on nuclear cost: Preliminary insights from a multiple factors learning curve and uranium market modeling

    International Nuclear Information System (INIS)

    Kahouli, Sondes

    2011-01-01

    This paper studies the effects of returns to scale, technological learning, i.e. learning-by-doing and learning-by-searching, and uranium price on the prospects of nuclear cost decrease. We use an extended learning curve specification, named multiple factors learning curve (MFLC). In a first stage, we estimate a single MFLC. In a second stage, we estimate the MFLC under the framework of simultaneous system of equations which takes into account the uranium supply and demand. This permits not only to enhance the reliability of the estimation by incorporating the uranium price formation mechanisms in the MFLC via the price variable, but also to give preliminary insights about uranium supply and demand behaviors and the associated effects on the nuclear expansion. Results point out that the nuclear cost has important prospects for decrease via capacity expansion, i.e. learning-by-doing effects. In contrast, they show that the learning-by-searching as well as the scale effects have a limited effect on the cost decrease prospects. Conversely, results also show that uranium price exerts a positive and significant effect on nuclear cost, implying that when the uranium price increases, the nuclear power generation cost decreases. Since uranium is characterized by important physical availability, and since it represents only a minor part in the total nuclear cost, we consider that in a context of increasing demand for nuclear energy the latter result can be explained by the fact that the positive learning effects on the cost of nuclear act in a way to dissipate the negative ones that an increase in uranium price may exert. Further, results give evidence of important inertia in the supply and demand sides as well as evidence of slow correlation between the uranium market and oil market which may limit the inter-fuels substituability effects, that is, nuclear capacity expansion and associated learning-by-doing benefits. - Highlights: → We study the prospects of nuclear cost

  11. Endoscopic Transsphenoidal Surgery Outcomes in 331 Nonfunctioning Pituitary Adenoma Cases After a Single Surgeon Learning Curve.

    Science.gov (United States)

    Kim, Jung Hee; Lee, Jung Hyun; Lee, Ji Hyun; Hong, A Ram; Kim, Yoon Ji; Kim, Yong Hwy

    2018-01-01

    The outcomes of recent endoscopic surgery of nonfunctioning pituitary adenomas (NFPAs) are controversial when compared with traditional microscopic surgery. We aimed to assess the outcomes of endoscopic transsphenoidal surgeries performed by 1 surgeon with 7 years of experience and elucidate the predictive factors for surgical outcomes for NFPAs. We included 331 patients (155 men and 176 women) with clinical NFPAs who underwent transsphenoidal surgery because of visual symptoms by a single surgeon in Seoul National University Hospital from March 2010 to May 2016. We assessed the tumor removal rate, hormonal outcomes, visual outcomes, and complications. The gross total resection rate of endoscopic transsphenoidal surgery for NFPAs by a single surgeon was 74.9%. Cavernous sinus invasion, a high Knosp grade, large tumor size, previous surgery, and lack of surgical experience in the neurosurgeon elevated the risk for residual tumors. Visual deficits were improved in 73.4% of the patients, which was associated with tumor size, preoperative visual impairment score, previous radiation, and surgical experience. Hormonal status was improved in 15.4% and aggravated in 32.9% after surgery. There were no predictors for hormonal recovery. Transient diabetes insipidus (DI) was the most common complication (9.1%), and among these patients, 3.0% had persistent DI. Endoscopic transsphenoidal surgery by a well-experienced surgeon was an effective and safe treatment for NFPAs, but the hormonal outcomes were not changed compared with previous reports of microscopic surgery. Large tumor size and cavernous sinus invasion were still the barriers for achieving total resection. Copyright © 2017 Elsevier Inc. All rights reserved.

  12. Evaluation of the learning curve for thulium laser enucleation of the prostate with the aid of a simulator tool but without tutoring: comparison of two surgeons with different levels of endoscopic experience.

    Science.gov (United States)

    Saredi, Giovanni; Pirola, Giacomo Maria; Pacchetti, Andrea; Lovisolo, Jon Alexander; Borroni, Giacomo; Sembenini, Federico; Marconi, Alberto Mario

    2015-06-09

    The aim of this study was to determine the learning curve for thulium laser enucleation of the prostate (ThuLEP) for two surgeons with different levels of urological endoscopic experience. From June 2012 to August 2013, ThuLEP was performed on 100 patients in our institution. We present the results of a prospective evaluation during which we analyzed data related to the learning curves for two surgeons of different levels of experience. The prostatic adenoma volumes ranged from 30 to 130 mL (average 61.2 mL). Surgeons A and B performed 48 and 52 operations, respectively. Six months after surgery, all patients were evaluated with the International Prostate Symptom Score questionnaire, uroflowmetry, and prostate-specific antigen test. Introduced in 2010, ThuLEP consists of blunt enucleation of the prostatic apex and lobes using the sheath of the resectoscope. This maneuver allows clearer visualization of the enucleation plane and precise identification of the prostatic capsule. These conditions permit total resection of the prostatic adenoma and coagulation of small penetrating vessels, thereby reducing the laser emission time. Most of the complications in this series were encountered during morcellation, which in some cases was performed under poor vision because of venous bleeding due to surgical perforation of the capsule during enucleation. Based on this analysis, we concluded that it is feasible for laser-naive urologists with endoscopic experience to learn to perform ThuLEP without tutoring. Those statements still require further validation in larger multicentric study cohort by several surgeon. The main novelty during the learning process was the use of a simulator that faithfully reproduced all of the surgical steps in prostates of various shapes and volumes.

  13. The learning curve to achieve satisfactory completion rates in upper GI endoscopy: an analysis of a national training database.

    Science.gov (United States)

    Ward, S T; Hancox, A; Mohammed, M A; Ismail, T; Griffiths, E A; Valori, R; Dunckley, P

    2017-06-01

    The aim of this study was to determine the number of OGDs (oesophago-gastro-duodenoscopies) trainees need to perform to acquire competency in terms of successful unassisted completion to the second part of the duodenum 95% of the time. OGD data were retrieved from the trainee e-portfolio developed by the Joint Advisory Group on GI Endoscopy (JAG) in the UK. All trainees were included unless they were known to have a baseline experience of >20 procedures or had submitted data for 90% trainees had attained a 95% completion rate. Total number of OGDs performed, trainee age and experience in lower GI endoscopy were factors independently associated with OGD completion. There are limited published data on the OGD learning curve. This is the largest study to date analysing the learning curve for competency acquisition. The JAG competency requirement for 200 procedures appears appropriate. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/.

  14. The learning curve, interobserver, and intraobserver agreement of endoscopic confocal laser endomicroscopy in the assessment of mucosal barrier defects.

    Science.gov (United States)

    Chang, Jeff; Ip, Matthew; Yang, Michael; Wong, Brendon; Power, Theresa; Lin, Lisa; Xuan, Wei; Phan, Tri Giang; Leong, Rupert W

    2016-04-01

    Confocal laser endomicroscopy can dynamically assess intestinal mucosal barrier defects and increased intestinal permeability (IP). These are functional features that do not have corresponding appearance on histopathology. As such, previous pathology training may not be beneficial in learning these dynamic features. This study aims to evaluate the diagnostic accuracy, learning curve, inter- and intraobserver agreement for identifying features of increased IP in experienced and inexperienced analysts and pathologists. A total of 180 endoscopic confocal laser endomicroscopy (Pentax EC-3870FK; Pentax, Tokyo, Japan) images of the terminal ileum, subdivided into 6 sets of 30 were evaluated by 6 experienced analysts, 13 inexperienced analysts, and 2 pathologists, after a 30-minute teaching session. Cell-junction enhancement, fluorescein leak, and cell dropout were used to represent increased IP and were either present or absent in each image. For each image, the diagnostic accuracy, confidence, and quality were assessed. Diagnostic accuracy was significantly higher for experienced analysts compared with inexperienced analysts from the first set (96.7% vs 83.1%, P 0.86 for experienced observers. Features representative of increased IP can be rapidly learned with high inter- and intraobserver agreement. Confidence and image quality were significant predictors of accurate interpretation. Previous pathology training did not have an effect on learning. Copyright © 2016 American Society for Gastrointestinal Endoscopy. Published by Elsevier Inc. All rights reserved.

  15. Electronic learning can facilitate student performance in undergraduate surgical education: a prospective observational study

    Directory of Open Access Journals (Sweden)

    Gorey Thomas

    2005-06-01

    Full Text Available Abstract Background Our institution recently introduced a novel internet accessible computer aided learning (iCAL programme to complement existing surgical undergraduate teaching methods. On graduation of the first full cycle of undergraduate students to whom this resource was available we assessed the utility of this new teaching facility. Method The computer programme prospectively records usage of the system on an individual user basis. We evaluated the utilisation of the web-based programme and its impact on class ranking changes from an entry-test evaluation to an exit examination in surgery. Results 74.4% of students were able to access iCAL from off-campus internet access. The majority of iCAL usage (64.6% took place during working hours (08:00–18:00 with little usage on the weekend (21.1%. Working hours usage was positively associated with improvement in class rank (P = 0.025, n = 148 but out-of hours usage was not (P = 0.306. Usage during weekdays was associated with improved rank (P = 0.04, whereas weekend usage was not (P = 0.504. There were no significant differences in usage between genders (P = 0.3. Usage of the iCAL system was positively correlated with improvement in class rank from the entry to the exit examination (P = 0.046. Students with lower ranks on entry examination, were found to use the computer system more frequently (P = 0.01. Conclusion Electronic learning complements traditional teaching methods in undergraduate surgical teaching. Its is more frequently used by students achieving lower class ranking with traditional teaching methods, and this usage is associated with improvements in class ranking.

  16. Goal orientation in surgical residents: a study of the motivation behind learning.

    Science.gov (United States)

    Hoffman, Rebecca L; Hudak-Rosander, Cristina; Datta, Jashodeep; Morris, Jon B; Kelz, Rachel R

    2014-08-01

    The subconscious way in which an individual approaches learning, goal orientation (GO), has been shown to influence job satisfaction, job performance, and burnout in nonmedical cohorts. The aim of this study was to adapt and validate an instrument to assess GO in surgical residents, so that in the future, we can better understand how differences in motivation affect professional development. Residents were recruited to complete a 17-item survey adapted from the Patterns of Adaptive Learning Scales (PALS). The survey included three scales assessing GO in residency-specific terms. Items were scored on a 5-point Likert scale, and the psychometric properties of the adapted and original PALS were compared. Ninety-five percent of residents (61/64) participated. Median age was 30 y and 33% were female. Mean (standard deviation) scale scores for the adapted PALS were: mastery 4.30 (0.48), performance approach (PAP) 3.17 (0.99), and performance avoid 2.75 (0.88). Mean (standard deviation) scale scores for the original PALS items were: mastery 3.35 (1.02), PAP 2.76 (1.15), and performance avoid 2.41 (0.91). Cronbach alpha were α = 0.89 and α = 0.84 for the adapted PAP and avoid scales, respectively, which were comparable with the original scales. For the adapted mastery scale, α = 0.54. Exploratory factor analysis revealed five factors, and factor loadings for individual mastery items did not load consistently onto a single factor. This study represents the first steps in the development of a novel tool to measure GO among surgical residents. Understanding motivational psychology in residents may facilitate improved education and professional development. Copyright © 2014 Elsevier Inc. All rights reserved.

  17. From Experiment to Theory: What Can We Learn from Growth Curves?

    Science.gov (United States)

    Kareva, Irina; Karev, Georgy

    2018-01-01

    Finding an appropriate functional form to describe population growth based on key properties of a described system allows making justified predictions about future population development. This information can be of vital importance in all areas of research, ranging from cell growth to global demography. Here, we use this connection between theory and observation to pose the following question: what can we infer about intrinsic properties of a population (i.e., degree of heterogeneity, or dependence on external resources) based on which growth function best fits its growth dynamics? We investigate several nonstandard classes of multi-phase growth curves that capture different stages of population growth; these models include hyperbolic-exponential, exponential-linear, exponential-linear-saturation growth patterns. The constructed models account explicitly for the process of natural selection within inhomogeneous populations. Based on the underlying hypotheses for each of the models, we identify whether the population that it best fits by a particular curve is more likely to be homogeneous or heterogeneous, grow in a density-dependent or frequency-dependent manner, and whether it depends on external resources during any or all stages of its development. We apply these predictions to cancer cell growth and demographic data obtained from the literature. Our theory, if confirmed, can provide an additional biomarker and a predictive tool to complement experimental research.

  18. Analysis of learning curves in the on-the-job training of air traffic controllers

    NARCIS (Netherlands)

    Oprins, E.A.P.B.; Bruggraaff, E.; Roe, R.

    2011-01-01

    This chapter describes a competence-based assessment system, called CBAS, for air traffic control (ATC) simulator and on-the-job training (OJT), developed at Air Traffic Control The Netherlands (LVNL). In contrast with simulator training, learning processes in OJT are difficult to assess, because

  19. Subjective Estimates of Job Performance after Job Preview: Determinants of Anticipated Learning Curves

    Science.gov (United States)

    Ackerman, Phillip L.; Shapiro, Stacey; Beier, Margaret E.

    2011-01-01

    When people choose a particular occupation, they presumably make an implicit judgment that they will perform well on a job at some point in the future, typically after extensive education and/or on-the-job experience. Research on learning and skill acquisition has pointed to a power law of practice, where large gains in performance come early in…

  20. Modelling ramp-up curves to reflect learning: improving capacity planning in secondary pharmaceutical production

    DEFF Research Database (Denmark)

    Hansen, Klaus Reinholdt Nyhuus; Grunow, Martin

    2015-01-01

    availability at market launch is ensured. Our MILP model is applied to a real industry case study using three empirically observed ramp-up curves to demonstrate its value as decision support tool. We demonstrate the superiority of our volume-dependent method over the traditional time-dependent ramp......The experience gained during production ramp-up leads to an increase of the effective production capacity over time. However, full utilisation of production capacity is not always possible during ramp-up. In such cases, the experience gained and hence the available effective capacity...... are overestimated. We develop a new method, which captures ramp-up as a function of the cumulative production volume to better reflect the experience gained while producing the new product. The use of the more accurate and computationally effective approach is demonstrated for the case of secondary pharmaceutical...

  1. "They Have to Adapt to Learn": Surgeons' Perspectives on the Role of Procedural Variation in Surgical Education.

    Science.gov (United States)

    Apramian, Tavis; Cristancho, Sayra; Watling, Chris; Ott, Michael; Lingard, Lorelei

    2016-01-01

    Clinical research increasingly acknowledges the existence of significant procedural variation in surgical practice. This study explored surgeons' perspectives regarding the influence of intersurgeon procedural variation on the teaching and learning of surgical residents. This qualitative study used a grounded theory-based analysis of observational and interview data. Observational data were collected in 3 tertiary care teaching hospitals in Ontario, Canada. Semistructured interviews explored potential procedural variations arising during the observations and prompts from an iteratively refined guide. Ongoing data analysis refined the theoretical framework and informed data collection strategies, as prescribed by the iterative nature of grounded theory research. Our sample included 99 hours of observation across 45 cases with 14 surgeons. Semistructured, audio-recorded interviews (n = 14) occurred immediately following observational periods. Surgeons endorsed the use of intersurgeon procedural variations to teach residents about adapting to the complexity of surgical practice and the norms of surgical culture. Surgeons suggested that residents' efforts to identify thresholds of principle and preference are crucial to professional development. Principles that emerged from the study included the following: (1) knowing what comes next, (2) choosing the right plane, (3) handling tissue appropriately, (4) recognizing the abnormal, and (5) making safe progress. Surgeons suggested that learning to follow these principles while maintaining key aspects of surgical culture, like autonomy and individuality, are important social processes in surgical education. Acknowledging intersurgeon variation has important implications for curriculum development and workplace-based assessment in surgical education. Adapting to intersurgeon procedural variations may foster versatility in surgical residents. However, the existence of procedural variations and their active use in surgeons

  2. Designing learning curves for carbon capture based on chemical absorption according to the minimum work of separation

    International Nuclear Information System (INIS)

    Rochedo, Pedro R.R.; Szklo, Alexandre

    2013-01-01

    Highlights: • This work defines the minimum work of separation (MWS) for a capture process. • Findings of the analysis indicated a MWS of 0.158 GJ/t for post-combustion. • A review of commercially available processes based on chemical absorption was made. • A review of learning models was conducted, with the addition on a novel model. • A learning curve for post-combustion carbon capture was successfully designed. - Abstract: Carbon capture is one of the most important alternatives for mitigating greenhouse gas emissions in energy facilities. The post-combustion route based on chemical absorption with amine solvents is the most feasible alternative for the short term. However, this route implies in huge energy penalties, mainly related to the solvent regeneration. By defining the minimum work of separation (MWS), this study estimated the minimum energy required to capture the CO 2 emitted by coal-fired thermal power plants. Then, by evaluating solvents and processes and comparing it to the MWS, it proposes the learning model with the best fit for the post-combustion chemical absorption of CO 2 . Learning models are based on earnings from experience, which can include the intensity of research and development. In this study, three models are tested: Wright, DeJong and D and L. Findings of the thermochemical analysis indicated a MWS of 0.158 GJ/t for post-combustion. Conventional solvents currently present an energy penalty eight times the MWS. By using the MWS as a constraint, this study found that the D and L provided the best fit to the available data of chemical solvents and absorption plants. The learning rate determined through this model is very similar to the ones found in the literature

  3. Impact of cap-assisted colonoscopy on the learning curve and quality in colonoscopy: a randomized controlled trial.

    Science.gov (United States)

    Tang, Zhouwen; Zhang, Daniel S; Thrift, Aaron P; Patel, Kalpesh K

    2018-03-01

    Colonoscopy competency assessment in trainees traditionally has been informal. Comprehensive metrics such as the Assessment of Competency in Endoscopy (ACE) tool suggest that competency thresholds are higher than assumed. Cap-assisted colonoscopy (CAC) may improve competency, but data regarding novice trainees are lacking. We compared CAC versus standard colonoscopy (SC) performed by novice trainees in a randomized controlled trial. All colonoscopies performed by 3 gastroenterology fellows without prior experience were eligible for the study. Exclusion criteria included patient age 90 years, pregnancy, prior colon resection, diverticulitis, colon obstruction, severe hematochezia, referral for EMR, or a procedure done without patient sedation. Patients were randomized to either CAC or SC in a 1:1 fashion. The primary outcome was the independent cecal intubation rate (ICIR). Secondary outcomes were cecal intubation time, polyp detection rate, polyp miss rate, adenoma detection rate, ACE tool scores, and cumulative summation learning curves. A total of 203 colonoscopies were analyzed, 101 in CAC and 102 in SC. CAC resulted in a significantly higher cecal intubation rate, at 79.2% in CAC compared with 66.7% in SC (P = .04). Overall cecal intubation time was significantly shorter at 13.7 minutes for CAC versus 16.5 minutes for SC (P =.02). Cecal intubation time in the case of successful independent fellow intubation was not significantly different between CAC and SC (11.6 minutes vs 12.7 minutes; P = .29). Overall ACE tool motor and cognitive scores were higher with CAC. Learning curves for ICIR approached the competency threshold earlier with cap use but reached competency for only 1 fellow. The polyp detection rate, polyp miss rate, and adenoma detection rate were not significantly different between groups. CAC resulted in significant improvement in ICIR, overall ACE tool scores, and trend toward competency on learning curves when compared with SC in colonoscopy

  4. A 5-year perspective over robotic general surgery: indications, risk factors and learning curves.

    Science.gov (United States)

    Sgarbură, O; Tomulescu, V; Blajut, C; Popescu, I

    2013-01-01

    Robotic surgery has opened a new era in several specialties but the diffusion of medical innovation is slower indigestive surgery than in urology due to considerations related to cost and cost-efficiency. Studies often discuss the launching of the robotic program as well as the technical or clinical data related to specific procedures but there are very few articles evaluating already existing robotic programs. The aims of the present study are to evaluate the results of a five-year robotic program and to assess the evolution of indications in a center with expertise in a wide range of thoracic and abdominal robotic surgery. All consecutive robotic surgery cases performed in our center since the beginning of the program and prior to the 31st of December 2012 were included in this study, summing up to 734 cases throughout five years of experience in the field. Demographic, clinical, surgical and postoperative variables were recorded and analyzed.Comparative parametric and non-parametric tests, univariate and multivariate analyses and CUSUM analysis were performed. In this group, the average age was 50,31 years. There were 60,9% females and 39,1% males. 55,3% of all interventions were indicated for oncological disease. 36% of all cases of either benign or malignant etiology were pelvic conditions whilst 15,4% were esogastric conditions. Conversion was performed in 18 cases (2,45%). Mean operative time was 179,4Â+-86,06 min. Mean docking time was 11,16Â+-2,82 min.The mean hospital length of stay was 8,54 (Â+-5,1) days. There were 26,2% complications of all Clavien subtypes but important complications (Clavien III-V) only represented 6,2%.Male sex, age over 65 years old, oncological cases and robotic suturing were identified as risk factors for unfavorable outcomes. The present data support the feasibility of different and complex procedures in a general surgery department as well as the ascending evolution of a well-designed and well-conducted robotic program. From

  5. Surgical resident learning styles: faculty and resident accuracy at identification of preferences and impact on ABSITE scores.

    Science.gov (United States)

    Kim, Roger H; Gilbert, Timothy; Ristig, Kyle; Chu, Quyen D

    2013-09-01

    As a consequence of surgical resident duty hour restrictions, there is a need for faculty to utilize novel teaching methods to convey information in a more efficient manner. The current paradigm of surgical training, which has not changed significantly since the time of Halsted, assumes that all residents assimilate information in a similar fashion. However, recent data has shown that learners have preferences for the ways in which they receive and process information. The VARK model categorizes learners as visual (V), aural (A), read/write (R), and kinesthetic (K). The VARK learning style preferences of surgical residents have not been previously evaluated. In this study, the preferred learning styles of general surgery residents were determined, along with faculty and resident perception of resident learning styles. In addition, we hypothesized that American Board of Surgery In-Training Exam (ABSITE) scores are associated with preference for a read/write (R) learning style. The Fleming VARK learning styles inventory was administered to all general surgery residents at a university hospital-based program. Responses on the inventory were scored to determine the preferred learning style for each resident. Faculty members were surveyed to determine their accuracy in identifying the preferred learning style of each resident. All residents were also surveyed to determine their accuracy in identifying their peers' VARK preferences. Resident ABSITE scores were examined for association with preferred learning styles. Twenty-nine residents completed the inventory. Most (18 of 29, 62%) had a multimodal preference, although more than a third (11 of 29, 38%) demonstrated a single-modality preference. Seventy-six percent of all residents (22 of 29) had some degree of kinesthetic (K) learning, while under 50% (14 of 29) were aural (A) learners. Although not significant, dominant (R) learners had the highest mean ABSITE scores. Faculty identified residents' learning styles

  6. Technology learning in a global - local perspective: - the interplay between technology diffusion, niche markets and experience curves

    International Nuclear Information System (INIS)

    Martinsen, Thomas

    2010-01-01

    Preventing dangerous global climate change requires timely deployment of nascent energy technologies with zero or low Co2 emissions. Managing the shift to a common sustainable technology path calls for insight about the influence of global technological change on the national energy system. Moreover, national policies are required to promote the shift to the new technology path. This calls for methods to analyse the national energy system within a global perspective. The objective of the work presented in this thesis was to investigate interplay between technology diffusion, niche markets and technology learning from the perspective of a small open economy like Norway. More specifically, develop methods to include the influence of technology learning manifested in experience and learning curves into national energy-economy-environment models. Moreover, apply the methods to investigate the potential influence and sensitivity to technology learning in a small open economy. In this thesis three such methods have been developed, applied and its importance assessed using Norway as an example. In this work three models have been linked. They are the global Energy Technology Perspectives model operated by the International Energy Agency, the Norwegian Markal model at the Institute for Energy Technology and the macro economic model MSG6 at Statistics Norway. Method one and two has been developed to manage the interplay between the models. In a local perspective technology learning in the global market is perceived as spillover. Based upon a review of the characteristics of technological change and learning curves and its application to energy system modelling some criteria important for the parameterization and modelling of spillover in a small open economy are suggested. The first method incorporates spillover into the national Markal model. The second method establishes a soft-link between the national models. The soft-link served two purposes; to provide input on demand

  7. Initial laparoscopic basic skills training shortens the learning curve of laparoscopic suturing and is cost-effective.

    Science.gov (United States)

    Stefanidis, Dimitrios; Hope, William W; Korndorffer, James R; Markley, Sarah; Scott, Daniel J

    2010-04-01

    Laparoscopic suturing is an advanced skill that is difficult to acquire. Simulator-based skills curricula have been developed that have been shown to transfer to the operating room. Currently available skills curricula need to be optimized. We hypothesized that mastering basic laparoscopic skills first would shorten the learning curve of a more complex laparoscopic task and reduce resource requirements for the Fundamentals of Laparoscopic Surgery suturing curriculum. Medical students (n = 20) with no previous simulator experience were enrolled in an IRB-approved protocol, pretested on the Fundamentals of Laparoscopic Surgery suturing model, and randomized into 2 groups. Group I (n = 10) trained (unsupervised) until proficiency levels were achieved on 5 basic tasks; Group II (n = 10) received no basic training. Both groups then trained (supervised) on the Fundamentals of Laparoscopic Surgery suturing model until previously reported proficiency levels were achieved. Two weeks later, they were retested to evaluate their retention scores, training parameters, instruction requirements, and cost between groups using t-test. Baseline characteristics and performance were similar for both groups, and 9 of 10 subjects in each group achieved the proficiency levels. The initial performance on the simulator was better for Group I after basic skills training, and their suturing learning curve was shorter compared with Group II. In addition, Group I required less active instruction. Overall time required to finish the curriculum was similar for both groups; but the Group I training strategy cost less, with a savings of $148 per trainee. Teaching novices basic laparoscopic skills before a more complex laparoscopic task produces substantial cost savings. Additional studies are needed to assess the impact of such integrated curricula on ultimate educational benefit. Copyright (c) 2010 American College of Surgeons. Published by Elsevier Inc. All rights reserved.

  8. Mild decentration measured by a Scheimpflug camera and its impact on visual quality following SMILE in the early learning curve.

    Science.gov (United States)

    Li, Meiyan; Zhao, Jing; Miao, Huamao; Shen, Yang; Sun, Ling; Tian, Mi; Wadium, Elizabeth; Zhou, Xingtao

    2014-05-20

    To measure decentration following femtosecond laser small incision lenticule extraction (SMILE) for the correction of myopia and myopic astigmatism in the early learning curve, and to investigate its impact on visual quality. A total of 55 consecutive patients (100 eyes) who underwent the SMILE procedure were included. Decentration was measured using a Scheimpflug camera 6 months after surgery. Uncorrected and corrected distance visual acuity (UDVA, CDVA), manifest refraction, and wavefront errors were also measured. Associations between decentration and the preoperative spherical equivalent were analyzed, as well as the associations between decentration and wavefront aberrations. Regarding efficacy and safety, 40 eyes (40%) had an unchanged CDVA; 32 eyes (32%) gained one line; and 11 eyes (11%) gained two lines. Fifteen eyes (15%) lost one line of CDVA, and two eyes (2%) lost two lines. Ninety-nine of the treated eyes (99%) had a postoperative UDVA better than 1.0, and 100 eyes (100%) had a UDVA better than 0.8. The mean decentered displacement was 0.17 ± 0.09 mm. The decentered displacement of all treated eyes (100%) was within 0.50 mm; 70 eyes (70%) were within 0.20 mm; and 90 eyes (90%) were within 0.30 mm. The vertical coma showed the greatest increase in magnitude. The magnitude of horizontal decentration was found to be associated with an induced horizontal coma. This study suggests that, although mild decentration occurred in the early learning curve, good visual outcomes were achieved after the SMILE surgery. Special efforts to minimize induced vertical coma are necessary. Copyright 2014 The Association for Research in Vision and Ophthalmology, Inc.

  9. Learning curve in the detection of ovarian and deep endometriosis by using Magnetic Resonance

    International Nuclear Information System (INIS)

    Saba, Luca; Guerriero, Stefano; Sulis, Rosa; Pilloni, Monica; Ajossa, Silvia; Melis, Gianbenedetto; Mallarini, Giorgio

    2011-01-01

    Purpose: Determining if Magnetic Resonance Imaging (MRI) accuracy in diagnosing endometriosis is related to radiologist's expertise. Methods and materials: Written informed consent was obtained from all patients. This study is compliant to STARD method. Thirty patients (mean age 34; range 21-45 years) who had undergone MRI study for suspected endometriosis underwent surgery were retrospectively evaluated. MRI at 1.5 T was performed with SE and TSE sequences, T1 and T2-weighted with and without fat suppression. Four localizations were analyzed: ovary, uterosacral ligaments (USL), vaginal fornix and Rectum/Sigma/Douglas (R.S.D.). One radiologist evaluated each dataset; sensitivity, specificity, PPV and NPV, accuracy, LR+ and LR- were calculated according to the surgical results (first analysis). Dataset were then re-analyzed 12 months (second analysis) and 24 months (third analysis) later. McNemar test was applied to determine differences between the three analysis. Results: Sensitivity, specificity and accuracy for the ovary at the first analysis were 88.9%, 87% and 88%, at the second 92.6%, 87% and 90% whereas at the third 92.6%, 91.3% and 92%. Sensitivity, specificity and accuracy for the USLs at the first analysis were 62.5%, 76.9% and 70%, at the second 72%, 80.8% and 76% whereas at the third 80%, 84.6% and 82%. Sensitivity, specificity and accuracy for the vaginal fornix at the first analysis were 63.2%, 64.5% and 64%, at the second 73.7%, 77.4% and 76% whereas at the third 73.7%, 83.9% and 80%. Sensitivity, specificity and accuracy for the R.S.D. at the first analysis were 39.1%, 81.5% and 62%, at the second 62.5%, 85.2% and 76% whereas at the third 73.9%, 88.9% and 82%. McNemar test indicated a significant statistical difference in sensitivity in detecting nodules of endometriosis in R.S.D. between first and third analysis (p = 0.0215). The mean review time decreased (p = 0.0001). Conclusions: Accuracy of MRI in diagnosing endometriosis increased with

  10. Learning curve in the detection of ovarian and deep endometriosis by using Magnetic Resonance

    Energy Technology Data Exchange (ETDEWEB)

    Saba, Luca, E-mail: lucasaba@tiscali.it [Department of Science of the Images, Azienda Ospedaliero Universitaria di Cagliari, s.s. 554 Monserrato (Cagliari) 09045 (Italy); Guerriero, Stefano [Department of Gynaecology, Azienda Ospedaliero Universitaria di Cagliari, Via Ospedale (Cagliari) 09100 (Italy); Sulis, Rosa [Department of Science of the Images, Azienda Ospedaliero Universitaria di Cagliari, s.s. 554 Monserrato (Cagliari) 09045 (Italy); Pilloni, Monica [Department of Gynaecology, Azienda Ospedaliero Universitaria di Cagliari, Via Ospedale (Cagliari) 09100 (Italy); Ajossa, Silvia [Department of Science of the Images, Azienda Ospedaliero Universitaria di Cagliari, s.s. 554 Monserrato (Cagliari) 09045 (Italy); Department of Gynaecology, Azienda Ospedaliero Universitaria di Cagliari, Via Ospedale (Cagliari) 09100 (Italy); Melis, Gianbenedetto [Department of Gynaecology, Azienda Ospedaliero Universitaria di Cagliari, Via Ospedale (Cagliari) 09100 (Italy); Mallarini, Giorgio [Department of Science of the Images, Azienda Ospedaliero Universitaria di Cagliari, s.s. 554 Monserrato (Cagliari) 09045 (Italy)

    2011-08-15

    Purpose: Determining if Magnetic Resonance Imaging (MRI) accuracy in diagnosing endometriosis is related to radiologist's expertise. Methods and materials: Written informed consent was obtained from all patients. This study is compliant to STARD method. Thirty patients (mean age 34; range 21-45 years) who had undergone MRI study for suspected endometriosis underwent surgery were retrospectively evaluated. MRI at 1.5 T was performed with SE and TSE sequences, T1 and T2-weighted with and without fat suppression. Four localizations were analyzed: ovary, uterosacral ligaments (USL), vaginal fornix and Rectum/Sigma/Douglas (R.S.D.). One radiologist evaluated each dataset; sensitivity, specificity, PPV and NPV, accuracy, LR+ and LR- were calculated according to the surgical results (first analysis). Dataset were then re-analyzed 12 months (second analysis) and 24 months (third analysis) later. McNemar test was applied to determine differences between the three analysis. Results: Sensitivity, specificity and accuracy for the ovary at the first analysis were 88.9%, 87% and 88%, at the second 92.6%, 87% and 90% whereas at the third 92.6%, 91.3% and 92%. Sensitivity, specificity and accuracy for the USLs at the first analysis were 62.5%, 76.9% and 70%, at the second 72%, 80.8% and 76% whereas at the third 80%, 84.6% and 82%. Sensitivity, specificity and accuracy for the vaginal fornix at the first analysis were 63.2%, 64.5% and 64%, at the second 73.7%, 77.4% and 76% whereas at the third 73.7%, 83.9% and 80%. Sensitivity, specificity and accuracy for the R.S.D. at the first analysis were 39.1%, 81.5% and 62%, at the second 62.5%, 85.2% and 76% whereas at the third 73.9%, 88.9% and 82%. McNemar test indicated a significant statistical difference in sensitivity in detecting nodules of endometriosis in R.S.D. between first and third analysis (p = 0.0215). The mean review time decreased (p = 0.0001). Conclusions: Accuracy of MRI in diagnosing endometriosis increased with

  11. LEARNING CURVES OF LAPAROSCOPY – BARRIERS TO ADOPTION: A MNJIO EXPERIENCE!

    Directory of Open Access Journals (Sweden)

    Ramesh Maturi

    2016-06-01

    Full Text Available BACKGROUND Laparoscopy has been a new entry in the field of surgery with an active history of around just two decades. Today, it is in a position to challenge the conventional surgery which is in use since ages. It is making rapid inroads into various disciplines of surgery. Rapid improvements in optics, along with improvements in energy devices and mechanical stapling devices gave a fillip to acceptance of laparoscopy by the majority of surgeons. Also accumulating data and evidence has started influencing the sceptical, mobilising them to jump into the bandwagon. Barriers to adoption of new techniques, resistance to learning are common to human nature and it is necessary to have a systematic overview of the issues that might crop, so as to be prepared to overcome the problems of accepting laparoscopy into established centres of surgery. AIMS This publication is a reflection of our experience, our trials and tribulations in taking forward the laparoscopy program at our institution. This publication will give an overview of the steps involved in initiation of laparoscopy and aspires to be a source of answers, for day-to-day issues that crop during the process of learning laparoscopy. METHODS AND MATERIALS Just the way, executing laparoscopic surgery is a team effort, incorporating laparoscopy program in an institution is also a team effort where the members of team extend beyond the operating room. Involvement and co-operation of individuals across departments is a must along with benevolent seniors and a proactive administration. So we collated data by interviewing all the stakeholders of laparoscopy program, analysed observations of the faculty from the operating room and reviewed literature on the world wide web. Opinions of the administrators about their perceptions and the issues faced by the junior staff of the department were taken into consideration. Patients were interviewed before and after laparoscopic surgery. CONCLUSIONS Success at

  12. Use of the cumulative sum method (CUSUM) to assess the learning curves of ultrasound-guided continuous femoral nerve block.

    Science.gov (United States)

    Kollmann-Camaiora, A; Brogly, N; Alsina, E; Gilsanz, F

    2017-10-01

    Although ultrasound is a basic competence for anaesthesia residents (AR) there is few data available on the learning process. This prospective observational study aims to assess the learning process of ultrasound-guided continuous femoral nerve block and to determine the number of procedures that a resident would need to perform in order to reach proficiency using the cumulative sum (CUSUM) method. We recruited 19 AR without previous experience. Learning curves were constructed using the CUSUM method for ultrasound-guided continuous femoral nerve block considering 2 success criteria: a decrease of pain score>2 in a [0-10] scale after 15minutes, and time required to perform it. We analyse data from 17 AR for a total of 237 ultrasound-guided continuous femoral nerve blocks. 8/17 AR became proficient for pain relief, however all the AR who did more than 12 blocks (8/8) became proficient. As for time of performance 5/17 of AR achieved the objective of 12minutes, however all the AR who did more than 20 blocks (4/4) achieved it. The number of procedures needed to achieve proficiency seems to be 12, however it takes more procedures to reduce performance time. The CUSUM methodology could be useful in training programs to allow early interventions in case of repeated failures, and develop competence-based curriculum. Copyright © 2017 Sociedad Española de Anestesiología, Reanimación y Terapéutica del Dolor. Publicado por Elsevier España, S.L.U. All rights reserved.

  13. A MACHINE-LEARNING METHOD TO INFER FUNDAMENTAL STELLAR PARAMETERS FROM PHOTOMETRIC LIGHT CURVES

    International Nuclear Information System (INIS)

    Miller, A. A.; Bloom, J. S.; Richards, J. W.; Starr, D. L.; Lee, Y. S.; Butler, N. R.; Tokarz, S.; Smith, N.; Eisner, J. A.

    2015-01-01

    A fundamental challenge for wide-field imaging surveys is obtaining follow-up spectroscopic observations: there are >10 9 photometrically cataloged sources, yet modern spectroscopic surveys are limited to ∼few× 10 6 targets. As we approach the Large Synoptic Survey Telescope era, new algorithmic solutions are required to cope with the data deluge. Here we report the development of a machine-learning framework capable of inferring fundamental stellar parameters (T eff , log g, and [Fe/H]) using photometric-brightness variations and color alone. A training set is constructed from a systematic spectroscopic survey of variables with Hectospec/Multi-Mirror Telescope. In sum, the training set includes ∼9000 spectra, for which stellar parameters are measured using the SEGUE Stellar Parameters Pipeline (SSPP). We employed the random forest algorithm to perform a non-parametric regression that predicts T eff , log g, and [Fe/H] from photometric time-domain observations. Our final optimized model produces a cross-validated rms error (RMSE) of 165 K, 0.39 dex, and 0.33 dex for T eff , log g, and [Fe/H], respectively. Examining the subset of sources for which the SSPP measurements are most reliable, the RMSE reduces to 125 K, 0.37 dex, and 0.27 dex, respectively, comparable to what is achievable via low-resolution spectroscopy. For variable stars this represents a ≈12%-20% improvement in RMSE relative to models trained with single-epoch photometric colors. As an application of our method, we estimate stellar parameters for ∼54,000 known variables. We argue that this method may convert photometric time-domain surveys into pseudo-spectrographic engines, enabling the construction of extremely detailed maps of the Milky Way, its structure, and history

  14. Self-learning computers for surgical planning and prediction of postoperative alignment.

    Science.gov (United States)

    Lafage, Renaud; Pesenti, Sébastien; Lafage, Virginie; Schwab, Frank J

    2018-02-01

    In past decades, the role of sagittal alignment has been widely demonstrated in the setting of spinal conditions. As several parameters can be affected, identifying the driver of the deformity is the cornerstone of a successful treatment approach. Despite the importance of restoring sagittal alignment for optimizing outcome, this task remains challenging. Self-learning computers and optimized algorithms are of great interest in spine surgery as in that they facilitate better planning and prediction of postoperative alignment. Nowadays, computer-assisted tools are part of surgeons' daily practice; however, the use of such tools remains to be time-consuming. NARRATIVE REVIEW AND RESULTS: Computer-assisted methods for the prediction of postoperative alignment consist of a three step analysis: identification of anatomical landmark, definition of alignment objectives, and simulation of surgery. Recently, complex rules for the prediction of alignment have been proposed. Even though this kind of work leads to more personalized objectives, the number of parameters involved renders it difficult for clinical use, stressing the importance of developing computer-assisted tools. The evolution of our current technology, including machine learning and other types of advanced algorithms, will provide powerful tools that could be useful in improving surgical outcomes and alignment prediction. These tools can combine different types of advanced technologies, such as image recognition and shape modeling, and using this technique, computer-assisted methods are able to predict spinal shape. The development of powerful computer-assisted methods involves the integration of several sources of information such as radiographic parameters (X-rays, MRI, CT scan, etc.), demographic information, and unusual non-osseous parameters (muscle quality, proprioception, gait analysis data). In using a larger set of data, these methods will aim to mimic what is actually done by spine surgeons, leading

  15. Use of structure-activity landscape index curves and curve integrals to evaluate the performance of multiple machine learning prediction models

    Directory of Open Access Journals (Sweden)

    LeDonne Norman C

    2011-02-01

    Full Text Available Abstract Background Standard approaches to address the performance of predictive models that used common statistical measurements for the entire data set provide an overview of the average performance of the models across the entire predictive space, but give little insight into applicability of the model across the prediction space. Guha and Van Drie recently proposed the use of structure-activity landscape index (SALI curves via the SALI curve integral (SCI as a means to map the predictive power of computational models within the predictive space. This approach evaluates model performance by assessing the accuracy of pairwise predictions, comparing compound pairs in a manner similar to that done by medicinal chemists. Results The SALI approach was used to evaluate the performance of continuous prediction models for MDR1-MDCK in vitro efflux potential. Efflux models were built with ADMET Predictor neural net, support vector machine, kernel partial least squares, and multiple linear regression engines, as well as SIMCA-P+ partial least squares, and random forest from Pipeline Pilot as implemented by AstraZeneca, using molecular descriptors from SimulationsPlus and AstraZeneca. Conclusion The results indicate that the choice of training sets used to build the prediction models is of great importance in the resulting model quality and that the SCI values calculated for these models were very similar to their Kendall τ values, leading to our suggestion of an approach to use this SALI/SCI paradigm to evaluate predictive model performance that will allow more informed decisions regarding model utility. The use of SALI graphs and curves provides an additional level of quality assessment for predictive models.

  16. Use of structure-activity landscape index curves and curve integrals to evaluate the performance of multiple machine learning prediction models.

    Science.gov (United States)

    Ledonne, Norman C; Rissolo, Kevin; Bulgarelli, James; Tini, Leonard

    2011-02-07

    Standard approaches to address the performance of predictive models that used common statistical measurements for the entire data set provide an overview of the average performance of the models across the entire predictive space, but give little insight into applicability of the model across the prediction space. Guha and Van Drie recently proposed the use of structure-activity landscape index (SALI) curves via the SALI curve integral (SCI) as a means to map the predictive power of computational models within the predictive space. This approach evaluates model performance by assessing the accuracy of pairwise predictions, comparing compound pairs in a manner similar to that done by medicinal chemists. The SALI approach was used to evaluate the performance of continuous prediction models for MDR1-MDCK in vitro efflux potential. Efflux models were built with ADMET Predictor neural net, support vector machine, kernel partial least squares, and multiple linear regression engines, as well as SIMCA-P+ partial least squares, and random forest from Pipeline Pilot as implemented by AstraZeneca, using molecular descriptors from SimulationsPlus and AstraZeneca. The results indicate that the choice of training sets used to build the prediction models is of great importance in the resulting model quality and that the SCI values calculated for these models were very similar to their Kendall τ values, leading to our suggestion of an approach to use this SALI/SCI paradigm to evaluate predictive model performance that will allow more informed decisions regarding model utility. The use of SALI graphs and curves provides an additional level of quality assessment for predictive models.

  17. See me, touch me, heal me : the role of visuo-spatial ability in virtual anatomical learning and surgical simulator training

    NARCIS (Netherlands)

    Luursema, J.M.

    2010-01-01

    Medical learning and training are fields in transition. Catalyst in this change is the introduction of digital technology, for example in the form of simulator technology in surgical training, and virtual learning environments in anatomical learning. The primary aim of this thesis is to help

  18. Practical skills teaching in contemporary surgical education: how can educational theory be applied to promote effective learning?

    Science.gov (United States)

    Sadideen, Hazim; Kneebone, Roger

    2012-09-01

    Teaching practical skills is a core component of undergraduate and postgraduate surgical education. It is crucial to optimize our current learning and teaching models, particularly in a climate of decreased clinical exposure. This review explores the role of educational theory in promoting effective learning in practical skills teaching. Peer-reviewed publications, books, and online resources from national bodies (eg, the UK General Medical Council) were reviewed. This review highlights several aspects of surgical education, modeling them on current educational theory. These include the following: (1) acquisition and retention of motor skills (Miller's triangle; Fitts' and Posner's theory), (2) development of expertise after repeated practice and regular reinforcement (Ericsson's theory), (3) importance of the availability of expert assistance (Vygotsky's theory), (4) learning within communities of practice (Lave and Wenger's theory), (5) importance of feedback in learning practical skills (Boud, Schon, and Endes' theories), and (6) affective component of learning. It is hoped that new approaches to practical skills teaching are designed in light of our understanding of educational theory. Copyright © 2012 Elsevier Inc. All rights reserved.

  19. The influence of prior multiport experience on the learning curve for single-port thoracoscopic lobectomy: a multicentre comparative study†.

    Science.gov (United States)

    Martin-Ucar, Antonio E; Aragon, Javier; Bolufer Nadal, Sergio; Galvez Munoz, Carlos; Luo, Qigang; Perez Mendez, Itzel; Sihoe, Alan D L; Socci, Laura

    2017-06-01

    Competency in video-assisted thoracoscopic (VATS) lobectomy is estimated to be reached after the surgeon completes 50 cases. We wanted to explore the impact of competency in performing multiport VATS lobectomies on completing the needed number of single-port VATS. In a retrospective multicentre study, 6 individual surgeons (3 with previous competency in multiport VATS lobectomy and 3 without) submitted their first 50 cases of single-port VATS lobectomies. Extended and sublobar resections were excluded. Pre-, peri- and postoperative data were compared between the groups of surgeons. Chi-square and Wilcoxon's rank tests were used. The less experienced surgeons had previously attended dedicated training courses and visited with experts. A total of 300 cases were included [150 in Group A (surgeons with previous experience performing multiport VATS) and 150 in Group B (surgeons without extensive experience performing multiport VATS)]. Surgeons in Group B performed significantly more elective open lobectomies during their learning curve period than surgeons of Group A (58 vs 1). Patients in Group B were older and had more risk factors. There were 3 in-hospital deaths (respiratory failure, sepsis and fatal stroke). There were no differences between the groups in operative time, intensive care unit admissions, hospital stay, total complications, tumour size or number of N2 stations explored. Only the duration of intercostal drainage (2 vs 3 days, 0.012), incidence of respiratory tract infections (1% vs 7%, P  = 0.002) and conversion rates (4% vs 12%, P  = 0.018) were better in Group A. Patients characteristics played a role in the development of respiratory infections and longer drainage times but not in the need for conversion. Overall, postoperative outcomes during the learning curve period for single-port VATS lobectomies are not noticeably affected by previous multiport VATS experience. Less experienced surgeons were more selective in order to achieve

  20. Irreversible electroporation ablation (IRE of unresectable soft tissue tumors: learning curve evaluation in the first 150 patients treated.

    Directory of Open Access Journals (Sweden)

    Prejesh Philips

    Full Text Available BACKGROUND: Irreversible electroporation (IRE is a novel technology that uses peri-target discrete probes to deliver high-voltage localized electric current to induce cell death without thermal-induced coagulative necrosis. "Learnability" and consistently effective results by novice practitioners is essential for determining acceptance of novel techniques. This multi-center prospectively-collected database study evaluates the learning curve of IRE. METHODS: Analysis of 150 consecutive patients over 7 institutions from 9/2010-7/2012 was performed with patients treated divided into 3 groups A (1(st 50 patients treated, B (2(nd 50 and C (3(rd 50 patients treated chronologically and analyzed for outcomes. RESULTS: A total of 167 IRE procedures were performed, with a majority being liver(39.5% and pancreatic(35.5% lesions. The three groups were similar with respect to co-morbidities and demographics. Group C had larger lesions (3.9 vs 3 cm,p=0.001, more numerous lesions (3.2 vs 2.2,p=0.07, more vascular invasion(p=0.001, underwent more associated procedures(p=0.001 and had longer operative times(p<0.001. Despite this, they had similar complication and high-grade complication rates(p=0.24. Attributable morbidity rate was 13.3%(total 29.3% and high-grade complications were seen in 4.19%(total 12.6%. Pancreatic lesions(p=0.001 and laparotomy(p=0.001 were associated with complications. CONCLUSION: The review represents that single largest review of IRE soft tissue ablation demonstrating initial patient selection and safety. Over time, complex treatments of larger lesions and lesions with greater vascular involvement were performed without a significant increase in adverse effects or impact on local relapse free survival. This evolution demonstrates the safety profile of IRE and speed of graduation to more complex lesions, which was greater than 5 cases by institution. IRE is a safe and effective alternative to conventional ablation with a demonstrable

  1. Learned helplessness among families and surrogate decision-makers of patients admitted to medical, surgical, and trauma ICUs.

    Science.gov (United States)

    Sullivan, Donald R; Liu, Xinggang; Corwin, Douglas S; Verceles, Avelino C; McCurdy, Michael T; Pate, Drew A; Davis, Jennifer M; Netzer, Giora

    2012-12-01

    We sought to determine the prevalence of and clinical variables associated with learned helplessness, a psychologic state characterized by reduced motivation, difficulty in determining causality, and depression, in family members of patients admitted to ICUs. We conducted an observational survey study of a prospectively defined cohort of family members, spouses, and partners of patients admitted to surgical, medical, and trauma ICUs at a large academic medical center. Two validated instruments, the Learned Helplessness Scale and the Perceived Stress Scale, were used, and self-report of patient clinical characteristics and subject demographics were collected. Four hundred ninety-nine family members were assessed. Of these, 238 of 460 (51.7%) had responses consistent with a significant degree of learned helplessness. Among surrogate decision-makers, this proportion was 50% (92 of 184). Characteristics associated with significant learned helplessness included grade or high school education (OR, 3.27; 95% CI, 1.29-8.27; P = .01) and Perceived Stress Scale score > 18 (OR, 4.15; 95% CI, 2.65-6.50; P learned helplessness (OR, 0.56; 95% CI, 0.32-0.98; P = .05). The majority of family members of patients in the ICU experience significant learned helplessness. Risk factors for learned helplessness include lower educational levels, absence of an advance directive or DNR order, and higher stress levels among family members. Significant learned helplessness in family members may have negative implications in the collaborative decision-making process.

  2. Surgical treatment for the subclavian steal syndrome. Surgical indication and selection of procedures by {sup 123}I-IMP-SPECT imaging and {sup 99m}Tc-HSA accumulation curve in upper extremities

    Energy Technology Data Exchange (ETDEWEB)

    Fujita, Toyohisa; Tokunaga, Hidemori; Akita, Nobuhisa; Nonaka, Masahiro [Saiseikai Chuwa Hospital, Sakurai, Nara (Japan)

    1998-03-01

    To select reasonable operative procedures in the respective patients, we have studied the cerebral blood flow, especially in the posterior circulation, by {sup 123}I-IMP-SPECT imaging, and the blood flow in the upper extremities by {sup 99m}Tc-HSA accumulation curve in 11 patients with subclavian steal syndrome. Although all patients presented distinct symptoms and signs of vertebrobasilar insufficiency, {sup 123}I-IMP-SPECT early image demonstrated no evident finding of decreased blood flow in the posterior circulation. However, in the delayed image 5 out of 11 patients revealed laterality of IMP uptake in cerebellar hemisphere. Four patients presented symptoms of the upper extremities including arm claudication, and all of them revealed {sup 99m}Tc-HSA accumulation curve indicated decreased blood flow in the affected side of arm and forearm. We performed transposition of vertebral artery to common carotid artery in 7 patients without evidence of decreased blood flow in the upper extremities by {sup 99m}Tc-HSA accumulation curve, common carotid-subclavian dacron graft bypass in 3 cases with evidence of decreased blood flow in the upper extremities, and arch aorta-common carotid dacron graft bypass for the innominate artery occlusion. When the ischemia in the anterior circulation had existed in patients with multiple cerebrovascular occlusive disease, we first corrected the anterior circulation, and then performed the revascularization for the posterior circulation mentioned above by staged operation, resulting in successful treatment of all patients. (K.H.)

  3. Using learning curves on energy-efficient technologies to estimate future energy savings and emission reduction potentials in the U.S. iron and steel industry

    Energy Technology Data Exchange (ETDEWEB)

    Karali, Nihan [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Park, Won Young [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); McNeil, Michael A. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)

    2015-06-18

    Increasing concerns on non-sustainable energy use and climate change spur a growing research interest in energy efficiency potentials in various critical areas such as industrial production. This paper focuses on learning curve aspects of energy efficiency measures in the U.S iron and steel sector. A number of early-stage efficient technologies (i.e., emerging or demonstration technologies) are technically feasible and have the potential to make a significant contribution to energy saving and CO2 emissions reduction, but fall short economically to be included. However, they may also have the cost effective potential for significant cost reduction and/or performance improvement in the future under learning effects such as ‘learning-by-doing’. The investigation is carried out using ISEEM, a technology oriented, linear optimization model. We investigated how steel demand is balanced with/without the availability learning curve, compared to a Reference scenario. The retrofit (or investment in some cases) costs of energy efficient technologies decline in the scenario where learning curve is applied. The analysis also addresses market penetration of energy efficient technologies, energy saving, and CO2 emissions in the U.S. iron and steel sector with/without learning impact. Accordingly, the study helps those who use energy models better manage the price barriers preventing unrealistic diffusion of energy-efficiency technologies, better understand the market and learning system involved, predict future achievable learning rates more accurately, and project future savings via energy-efficiency technologies with presence of learning. We conclude from our analysis that, most of the existing energy efficiency technologies that are currently used in the U.S. iron and steel sector are cost effective. Penetration levels increases through the years, even though there is no price reduction. However, demonstration technologies are not economically

  4. High-Risk Breast Lesions: A Machine Learning Model to Predict Pathologic Upgrade and Reduce Unnecessary Surgical Excision.

    Science.gov (United States)

    Bahl, Manisha; Barzilay, Regina; Yedidia, Adam B; Locascio, Nicholas J; Yu, Lili; Lehman, Constance D

    2018-03-01

    Purpose To develop a machine learning model that allows high-risk breast lesions (HRLs) diagnosed with image-guided needle biopsy that require surgical excision to be distinguished from HRLs that are at low risk for upgrade to cancer at surgery and thus could be surveilled. Materials and Methods Consecutive patients with biopsy-proven HRLs who underwent surgery or at least 2 years of imaging follow-up from June 2006 to April 2015 were identified. A random forest machine learning model was developed to identify HRLs at low risk for upgrade to cancer. Traditional features such as age and HRL histologic results were used in the model, as were text features from the biopsy pathologic report. Results One thousand six HRLs were identified, with a cancer upgrade rate of 11.4% (115 of 1006). A machine learning random forest model was developed with 671 HRLs and tested with an independent set of 335 HRLs. Among the most important traditional features were age and HRL histologic results (eg, atypical ductal hyperplasia). An important text feature from the pathologic reports was "severely atypical." Instead of surgical excision of all HRLs, if those categorized with the model to be at low risk for upgrade were surveilled and the remainder were excised, then 97.4% (37 of 38) of malignancies would have been diagnosed at surgery, and 30.6% (91 of 297) of surgeries of benign lesions could have been avoided. Conclusion This study provides proof of concept that a machine learning model can be applied to predict the risk of upgrade of HRLs to cancer. Use of this model could decrease unnecessary surgery by nearly one-third and could help guide clinical decision making with regard to surveillance versus surgical excision of HRLs. © RSNA, 2017.

  5. Use of a machine learning algorithm to classify expertise: analysis of hand motion patterns during a simulated surgical task.

    Science.gov (United States)

    Watson, Robert A

    2014-08-01

    To test the hypothesis that machine learning algorithms increase the predictive power to classify surgical expertise using surgeons' hand motion patterns. In 2012 at the University of North Carolina at Chapel Hill, 14 surgical attendings and 10 first- and second-year surgical residents each performed two bench model venous anastomoses. During the simulated tasks, the participants wore an inertial measurement unit on the dorsum of their dominant (right) hand to capture their hand motion patterns. The pattern from each bench model task performed was preprocessed into a symbolic time series and labeled as expert (attending) or novice (resident). The labeled hand motion patterns were processed and used to train a Support Vector Machine (SVM) classification algorithm. The trained algorithm was then tested for discriminative/predictive power against unlabeled (blinded) hand motion patterns from tasks not used in the training. The Lempel-Ziv (LZ) complexity metric was also measured from each hand motion pattern, with an optimal threshold calculated to separately classify the patterns. The LZ metric classified unlabeled (blinded) hand motion patterns into expert and novice groups with an accuracy of 70% (sensitivity 64%, specificity 80%). The SVM algorithm had an accuracy of 83% (sensitivity 86%, specificity 80%). The results confirmed the hypothesis. The SVM algorithm increased the predictive power to classify blinded surgical hand motion patterns into expert versus novice groups. With further development, the system used in this study could become a viable tool for low-cost, objective assessment of procedural proficiency in a competency-based curriculum.

  6. Three-dimensional computer graphics for surgical procedure learning: Web three-dimensional application for cleft lip repair.

    Science.gov (United States)

    Kobayashi, Masahiro; Nakajima, Tatsuo; Mori, Ayako; Tanaka, Daigo; Fujino, Toyomi; Chiyokura, Hiroaki

    2006-05-01

    In surgical procedures for cleft lip, surgeons attempt to use various skin incisions and small flaps to achieve a better and more natural shape postoperatively. They must understand the three-dimensional (3D) structure of the lips. However, they may have difficulty learning the surgical procedures precisely from normal textbooks with two-dimensional illustrations. Recent developments in 3D computed tomography (3D-CT) and laser stereolithography have enabled surgeons to visualize the structures of cleft lips from desired viewpoints. However, this method cannot reflect the advantages offered by specific surgical procedures. To solve this problem, we used the benefits offered by 3D computer graphics (3D-CG) and 3D animation. By using scanning 3D-CT image data of patients with cleft lips, 3D-CG models of the cleft lips were created. Several animations for surgical procedures such as incision designs, rotation of small skin flaps, and sutures were made. This system can recognize the details of an operation procedure clearly from any viewpoint, which cannot be acquired from the usual textbook illustrations. This animation system can be used for developing new skin-flap design, understanding the operational procedure, and using tools in case presentations. The 3D animations can also be uploaded to the World Wide Web for use in teleconferencing.

  7. Two-year Outcomes from a Single Surgeon's Learning Curve Experience of Oblique Lateral Interbody Fusion without Intraoperative Neuromonitoring.

    Science.gov (United States)

    Woods, Kamal; Fonseca, Ahtziri; Miller, Larry E

    2017-12-22

    Introduction Oblique lumbar interbody fusion (OLIF) is a newer procedure that avoids the psoas and lumbosacral plexus due to its oblique trajectory into the retroperitoneal space. While early experience with OLIF is reassuring, the longer-term clinical efficacy has not been well established. The purpose of this study was to describe two-year clinical outcomes with OLIF performed by a single surgeon during the learning curve without the aid of the neuromonitoring. Materials and methods Chart review was performed for the consecutive patients who underwent OLIF by a single surgeon. Back pain severity on a visual analog scale (VAS) and Oswestry Disability Index (ODI) were collected preoperatively and postoperatively at six weeks, three months, six months, one year and two years. Results A total of 21 patients (38 levels) were included in this study. The indications for surgery were degenerative disc disease (n=10, 47.6%), spondylolisthesis (n=9, 42.9%) and spinal stenosis (n=6, 28.6%). The median operating room time was 351 minutes (interquartile range (IQR): 279-406 minutes), blood loss was 40 ml (IQR: 30-150 ml), and hospital stay was 2.0 days (IQR: 1.0-3.5 days). The complication rate was 9.5%, both venous injuries. There were no other perioperative complications. Back pain severity decreased by 70%, on average, over two years (p safe and clinically efficacious for up to two years. The complication rate in this cohort is similar to other published OLIF series and appears acceptable when compared to the lateral lumbar interbody fusion (LLIF) and the anterior lumbar interbody fusion (ALIF). No motor or sensory deficits were observed in this study, supporting the premise that the neuromonitoring is unnecessary in OLIF.

  8. The learning curve for access creation in solo ultrasonography-guided percutaneous nephrolithotomy and the associated skills.

    Science.gov (United States)

    Yu, Weimin; Rao, Ting; Li, Xing; Ruan, Yuan; Yuan, Run; Li, Chenglong; Li, Haoyong; Cheng, Fan

    2017-03-01

    The aim of the current trial was to evaluate the learning curve of access creation through solo ultrasonography (US)-guided percutaneous nephrolithotomy (PCNL), and clarify the technical details of the procedure. We evaluated the first 240 solo US-guided PCNLs performed by one surgeon at our institution. The data including the puncture procedure, access characteristics, access-related complications and stone-free rates were assessed in four sequential groups. The puncture duration and number of times decreased from a mean of 4.4 min and 2.1 times for the first 60 patients to 1.3 min and 1.2 times for the last 60 patients. There was a significant decrease from 3.7 min and 1.8 times for the 61th-120th patients to 1.5 min and 1.3 times for the 121th-180th patients. All of the access-related severe bleeding appeared in the first 120 patients, while perforations only occurred in the first 60 patients. The stone-free rates were 68.3, 83.3, 90.0, and 93.3% for the four sequential groups. The increase in experience lead to an improvement in the puncture duration and times, which accompany with better stone-free rates and lower complications. We propose that 60 operations are sufficient to gain competency, and a cutoff point of 120 operations will allow the surgeon to achieve excellence in the solo US-guided PCNL.

  9. Ultrasensitive prostate specific antigen assay following laparoscopic radical prostatectomy--an outcome measure for defining the learning curve.

    Science.gov (United States)

    Viney, R; Gommersall, L; Zeif, J; Hayne, D; Shah, Z H; Doherty, A

    2009-07-01

    Radical retropubic prostatectomy (RRP) performed laparoscopically is a popular treatment with curative intent for organ-confined prostate cancer. After surgery, prostate specific antigen (PSA) levels drop to low levels which can be measured with ultrasensitive assays. This has been described in the literature for open RRP but not for laparoscopic RRP. This paper describes PSA changes in the first 300 consecutive patients undergoing non-robotic laparoscopic RRP by a single surgeon. To use ultrasensitive PSA (uPSA) assays to measure a PSA nadir in patients having laparoscopic radical prostatectomy below levels recorded by standard assays. The aim was to use uPSA nadir at 3 months' post-prostatectomy as an early surrogate end-point of oncological outcome. In so doing, laparoscopic oncological outcomes could then be compared with published results from other open radical prostatectomy series with similar end-points. Furthermore, this end-point could be used in the assessment of the surgeon's learning curve. Prospective, comprehensive, demographic, clinical, biochemical and operative data were collected from all patients undergoing non-robotic laparoscopic RRP. We present data from the first 300 consecutive patients undergoing laparoscopic RRP by a single surgeon. uPSA was measured every 3 months post surgery. Median follow-up was 29 months (minimum 3 months). The likelihood of reaching a uPSA of bench-marking performance. With experience, a surgeon can achieve in excess of an 80% chance of obtaining a uPSA nadir of < or = 0.01 ng/ml at 3 months after laparoscopic RRP for a British population. This is equivalent to most published open series.

  10. Computational Sensing of Staphylococcus aureus on Contact Lenses Using 3D Imaging of Curved Surfaces and Machine Learning.

    Science.gov (United States)

    Veli, Muhammed; Ozcan, Aydogan

    2018-03-27

    We present a cost-effective and portable platform based on contact lenses for noninvasively detecting Staphylococcus aureus, which is part of the human ocular microbiome and resides on the cornea and conjunctiva. Using S. aureus-specific antibodies and a surface chemistry protocol that is compatible with human tears, contact lenses are designed to specifically capture S. aureus. After the bacteria capture on the lens and right before its imaging, the captured bacteria are tagged with surface-functionalized polystyrene microparticles. These microbeads provide sufficient signal-to-noise ratio for the quantification of the captured bacteria on the contact lens, without any fluorescent labels, by 3D imaging of the curved surface of each lens using only one hologram taken with a lens-free on-chip microscope. After the 3D surface of the contact lens is computationally reconstructed using rotational field transformations and holographic digital focusing, a machine learning algorithm is employed to automatically count the number of beads on the lens surface, revealing the count of the captured bacteria. To demonstrate its proof-of-concept, we created a field-portable and cost-effective holographic microscope, which weighs 77 g, controlled by a laptop. Using daily contact lenses that are spiked with bacteria, we demonstrated that this computational sensing platform provides a detection limit of ∼16 bacteria/μL. This contact-lens-based wearable sensor can be broadly applicable to detect various bacteria, viruses, and analytes in tears using a cost-effective and portable computational imager that might be used even at home by consumers.

  11. Putting experience curves in context : links to and between technology development, market diffusion, learning mechanisms and systems innovation theory

    NARCIS (Netherlands)

    Junginger, M.; Suurs, R.; Verbong, G.P.J.; Schaeffer, G.J.; Sark, W. van; Faaij, A. xx

    2010-01-01

    As far as the experience curve approach goes, the focus is mainly on quantifying the cost reductions of the technological artefact (e.g. a wind turbine or biomass power plant) due to technological development. However, the experience curve by itself offers no explanation why costs should decline in

  12. The learning curve for narrow-band imaging in the diagnosis of precancerous gastric lesions by using Web-based video.

    Science.gov (United States)

    Dias-Silva, Diogo; Pimentel-Nunes, Pedro; Magalhães, Joana; Magalhães, Ricardo; Veloso, Nuno; Ferreira, Carlos; Figueiredo, Pedro; Moutinho, Pedro; Dinis-Ribeiro, Mário

    2014-06-01

    A simplified narrow-band imaging (NBI) endoscopy classification of gastric precancerous and cancerous lesions was derived and validated in a multicenter study. This classification comes with the need for dissemination through adequate training. To address the learning curve of this classification by endoscopists with differing expertise and to assess the feasibility of a YouTube-based learning program to disseminate it. Prospective study. Five centers. Six gastroenterologists (3 trainees, 3 fully trained endoscopists [FTs]). Twenty tests provided through a Web-based program containing 10 randomly ordered NBI videos of gastric mucosa were taken. Feedback was sent 7 days after every test submission. Measures of accuracy of the NBI classification throughout the time. From the first to the last 50 videos, a learning curve was observed with a 10% increase in global accuracy, for both trainees (from 64% to 74%) and FTs (from 56% to 65%). After 200 videos, sensitivity and specificity of 80% and higher for intestinal metaplasia were observed in half the participants, and a specificity for dysplasia greater than 95%, along with a relevant likelihood ratio for a positive result of 7 to 28 and likelihood ratio for a negative result of 0.21 to 0.82, were achieved by all of the participants. No constant learning curve was observed for the identification of Helicobacter pylori gastritis and sensitivity to dysplasia. The trainees had better results in all of the parameters, except specificity for dysplasia, compared with the FTs. Globally, participants agreed that the program's structure was adequate, except on the feedback, which should have consisted of a more detailed explanation of each answer. No formal sample size estimate. A Web-based learning program could be used to teach and disseminate classifications in the endoscopy field. In this study, an NBI classification for gastric mucosal features seems to be easily learned for the identification of gastric preneoplastic

  13. Learning from the Sun. Analysis of the use of experience curves for energy policy purposes. The case of photovoltaic power. Final report of the Photex project

    International Nuclear Information System (INIS)

    Schaeffer, G.J.; Seebregts, A.J.; Beurskens, L.W.M.; De Moor, H.H.C.; Alsema, E.; Sark, W.; Durstewicz, M.; Perrin, M.; Boulanger, P.; Laukamp, H.; Zuccaro, C.

    2004-08-01

    Since the 1990s energy policy scientists have started to explore the possibilities of using the experience curve approach for energy policy making. The concept of the experience curve is simple, at least in principle. It states that, for every doubling of cumulative produced capacity of a product or technology, the cost for making it declines with a fixed percentage (learning rate). Historical statistical analysis can be used to define this percentage. Extrapolating the trend thus found, into the future will then give relevant information about future cost developments and will also give information how much 'learning money' will be needed to get to the break-even point. The Photex project used the development of solar PV as a case to further explore this approach, and also to deduce lessons for PV policy. Other aims were to look at learning rates of the different components of PV-systems and to combine the experience curve analyses with bottom-up engineering studies. The main conclusion with regard to the use of experience curves for energy policy making is that this is an interesting approach, but that such an analysis should be done with much care. For the historical analysis the availability of reliable and firm data is essential. As cost data often are not available, price data could be used as a proxy, as long as sufficient long time ranges are used. Also, the analyst should take care he considers the right learning system boundaries. Furthermore the number of years to be included in the statistical analysis should at least be 10 years and this period sample should not over-represent stable price periods or periods of steep price decline. If possible, data uncertainties should be taken into account as well. An interesting finding was that, at least in the case of PV, the learning rate is not a constant, but can vary over time. In the case of PV it improved from 20% to 23%. Extrapolations into the future should take uncertainties into account and always be

  14. The effects of cooperative learning on students enrolled in a level 1 medical-surgical nursing course.

    Science.gov (United States)

    Gumbs, J

    2001-01-01

    This study was undertaken to create an environment that the literature contends will be more conducive to learning and one that will build the necessary social skills impacting students' performance. These social skills are essential if a nurse is to be effective in her role as a competent provider of care as well as an effective member of the inter-disciplinary health care team. The concept of cooperative learning was applied to nursing theoretical content in an effort to (a) decrease attrition rates in a first level medical-surgical nursing course, (b) increase student's knowledge and (c) enhance student's patient-teaching skills. Increased knowledge was assessed by student's performance on teacher-made paper and pencil examinations. The Classroom Life Instrument questionnaire was used for feedback on the teaching strategy and the Griffin tool was the basis for the pre-test and post-test assessment and implementation of the patient teaching plan.

  15. Impact of learning curve and technical changes on dosimetry in low-dose brachytherapy for prostate cancer

    Energy Technology Data Exchange (ETDEWEB)

    Le Fur, E. [CHU Brest (France). Radiation Therapy Dept.; Universite de Bretagne Occidentale, Brest (France). Faculte de Medecine et des Sciences de la Sante; Malhaire, J.P.; Baverez, D.; Schlurmann, F. [CHU Brest (France). Radiation Therapy Dept.; Delage, F.; Perrouin-Verbe, M.A. [CHU Brest (France). Urology Dept.; Guerif, S. [University Hospital La Miletrie, Poitiers (France). Radiation Therapy Dept.; Poitiers Univ. (France); Fournier, G.; Valeri, A. [CHU Brest (France). Urology Dept.; Universite de Bretagne Occidentale, Brest (France). Faculte de Medecine et des Sciences de la Sante; Universite Europeenne de Bretagne, Rennes (France); APHP, Hopital Tenon, Paris (France). CeRe.PP; Pradier, O. [CHU Brest (France). Radiation Therapy Dept.; Universite de Bretagne Occidentale, Brest (France). Faculte de Medecine et des Sciences de la Sante; Universite Europeenne de Bretagne, Rennes (France); CHU Brest (France). LaTIM, INSERM U650

    2012-12-15

    Purpose: To assess the impact of experience and technical changes on peri- and postimplantation (1 month later) dosimetry for permanent prostate brachytherapy (PPB). Patients and methods: From July 2003 to May 2010, 150 prostate cancer patients underwent low-dose, loose-seed I{sup 125} PPB as monotherapy with intraoperative planning. Patients were divided into three groups - P1 (n = 64), P2 (n = 45), P3 (n = 41) - according to the technical changes that occurred during the study period: use of an automatic stepper at the beginning of P2 and a high-frequency ultrasound probe in P3. Peri- and postimplantation dosimetric parameters (on day 30) were reported: D90 (dose received by 90% of prostate volume), V100 and V150 (prostate volume receiving, respectively, 100% and 150% of the prescribed dose), D2 cc and D0.1 cc (doses received by 2 cc and 0.1 cc of the rectum), R100 (rectum volume that received 100% of the prescribed dose), and D10 and D30 (doses received by 10% and 30% of the urethra, only during peri-implantation). Results: We observed a decrease in the number of needles and seeds used over time. The mean peri-implantation D90 was 187.52 Gy without a significant difference between the three periods (p = 0.48). The postimplantation D90, V100, and V150 parameters were, respectively, 168.3 Gy, 91.9%, and 55% with no significant difference between the three periods. The peri-implantation and postimplantation D0.1 cc and R100 significantly decreased over time; on day 30: D0.1 cc P1 = 223.1 Gy vs. D0.1 cc P3 = 190.4 Gy (p = 8.10- 5) and R100 P1 = 1.06 cc vs. R100 P3 = 0.53 cc (p = 0.0008). Conclusion: We observed a learning curve for the implantation parameters, which led to a significant decrease in the rectal doses without having any impact on the prostate dosimetric parameters. (orig.)

  16. Impact of learning curve and technical changes on dosimetry in low-dose brachytherapy for prostate cancer

    International Nuclear Information System (INIS)

    Le Fur, E.; Fournier, G.; Valeri, A.; Universite de Bretagne Occidentale, Brest; Universite Europeenne de Bretagne, Rennes; APHP, Hopital Tenon, Paris; Pradier, O.; Universite de Bretagne Occidentale, Brest; Universite Europeenne de Bretagne, Rennes; CHU Brest

    2012-01-01

    Purpose: To assess the impact of experience and technical changes on peri- and postimplantation (1 month later) dosimetry for permanent prostate brachytherapy (PPB). Patients and methods: From July 2003 to May 2010, 150 prostate cancer patients underwent low-dose, loose-seed I 125 PPB as monotherapy with intraoperative planning. Patients were divided into three groups - P1 (n = 64), P2 (n = 45), P3 (n = 41) - according to the technical changes that occurred during the study period: use of an automatic stepper at the beginning of P2 and a high-frequency ultrasound probe in P3. Peri- and postimplantation dosimetric parameters (on day 30) were reported: D90 (dose received by 90% of prostate volume), V100 and V150 (prostate volume receiving, respectively, 100% and 150% of the prescribed dose), D2 cc and D0.1 cc (doses received by 2 cc and 0.1 cc of the rectum), R100 (rectum volume that received 100% of the prescribed dose), and D10 and D30 (doses received by 10% and 30% of the urethra, only during peri-implantation). Results: We observed a decrease in the number of needles and seeds used over time. The mean peri-implantation D90 was 187.52 Gy without a significant difference between the three periods (p = 0.48). The postimplantation D90, V100, and V150 parameters were, respectively, 168.3 Gy, 91.9%, and 55% with no significant difference between the three periods. The peri-implantation and postimplantation D0.1 cc and R100 significantly decreased over time; on day 30: D0.1 cc P1 = 223.1 Gy vs. D0.1 cc P3 = 190.4 Gy (p = 8.10- 5) and R100 P1 = 1.06 cc vs. R100 P3 = 0.53 cc (p = 0.0008). Conclusion: We observed a learning curve for the implantation parameters, which led to a significant decrease in the rectal doses without having any impact on the prostate dosimetric parameters. (orig.)

  17. Effective and efficient learning in the operating theater with intraoperative video-enhanced surgical procedure training

    NARCIS (Netherlands)

    van Det, M.J.; Meijerink, W.J.; Hoff, C.; Middel, B.; Pierie, J.P.

    INtraoperative Video Enhanced Surgical procedure Training (INVEST) is a new training method designed to improve the transition from basic skills training in a skills lab to procedural training in the operating theater. Traditionally, the master-apprentice model (MAM) is used for procedural training

  18. Getting educated: e-learning resources in the design and execution of surgical trials.

    Science.gov (United States)

    Bains, Simrit

    2009-01-01

    An evidence-based approach to research, which includes important aspects such as critical appraisal, is essential for the effective conduct of clinical trials. Researchers who are interested in educating themselves about its principles in order to incorporate them into their trials face challenges when attempting to acquire this information from traditional learning sources. E-learning resources offer an intriguing possibility of overcoming the challenges posed by traditional learning, and show promise as a way to expand accessibility to quality education about evidence-based principles. An assessment of existing e-learning resources reveals positive educational avenues for researchers, although significant flaws exist. The Global EducatorTM by Global Research Solutions addresses many of these flaws and is an e-learning resource that combines convenience with comprehensiveness.

  19. Surgical Fires and Operative Burns: Lessons Learned From a 33-Year Review of Medical Litigation.

    Science.gov (United States)

    Choudhry, Asad J; Haddad, Nadeem N; Khasawneh, Mohammad A; Cullinane, Daniel C; Zielinski, Martin D

    2017-03-01

    We aimed to understand the setting and litigation outcomes of surgical fires and operative burns. Westlaw, an online legal research data-set, was utilized. Data were collected on patient, procedure, and case characteristics. One hundred thirty-nine cases were identified; 114 (82%) operative burns and 25 (18%) surgical fires. Median plaintiff (patient) age was 46 (IQR:28-59). Most common site of operative burn was the face (26% [n = 36]). Most common source of injury was a high energy device (43% [n = 52]). Death was reported in 2 (1.4%) cases. Plaintiff age <18 vs age 18-50 and mention of a non-surgical physician as a defendant both were shown to be independently associated with an award payout (OR = 4.90 [95% CI, 1.23-25.45]; p = .02) and (OR = 4.50 [95% CI, 1.63-13.63]; p = .003) respectively. Plaintiff award payment (settlement or plaintiff verdict) was reported in 83 (60%) cases; median award payout was $215,000 (IQR: $82,000-$518,000). High energy devices remain as the most common cause of injury. Understanding and addressing pitfalls in operative care may mitigate errors and potentially lessen future liability. III. Copyright © 2016 Elsevier Inc. All rights reserved.

  20. Colorectal endoscopic submucosal dissection (ESD) in the West - when can satisfactory results be obtained? A single-operator learning curve analysis.

    Science.gov (United States)

    Spychalski, Michał; Skulimowski, Aleksander; Dziki, Adam; Saito, Yutaka

    2017-12-01

    Up to date we lack a detailed description of the colorectal endoscopic submucosal dissection (ESD) learning curve, that would represent the experience of the Western center. The aim of this study was to define the critical points of the learning curve and to draw up lesions qualification guidelines tailored to the endoscopists experience. We have carried out a single center prospective study. Between June 2013 and December 2016, 228 primary colorectal lesions were managed by ESD procedure. In order to create a learning curve model and to carry out the analysis the cases were divided into six periods, each consisting of 38 cases. The overall en bloc resection rate was 79.39%. The lowest en bloc resection rate (52.36%) was observed in the first period. After completing 76 procedures, the resection rate surged to 86% and it was accompanied by the significant increase in the mean procedure speed of ≥9 cm 2 /h. Lesions localization and diameter had a signification impact on the outcomes. After 76 procedures, en bloc resection rate of 90.9 and 90.67% were achieved for the left side of colon and rectum, respectively. In the right side of colon statistically significant lower resection rate of 67.57% was observed. We have proved that in the setting of the Western center, colorectal ESD can yield excellent results. It seems that the key to the success during the learning period is 'tailoring' lesions qualification guidelines to the experience of the endoscopist, as lesions diameter and localization highly influence the outcomes.

  1. Establishing pediatric surgical services in emerging countries: What the first world can learn from Vanuatu.

    Science.gov (United States)

    Leodoro, Basil M; Beasley, Spencer W; Maoate, Kiki

    2015-05-01

    Conventional surgical aid to emerging countries often does little to build capacity or infrastructure. An evolving model in the South Pacific has been designed to promote local expertise by training local surgeons to a high standard and helping establish sustainable pediatric surgical services in those regions. This review identifies the key elements required to improve and expand local specialist pediatric surgical capacity in Vanuatu. It highlights some of the challenges that face external agencies in helping to create sufficient local infrastructure to achieve these goals and describes how the impediments can be overcome. We conducted a review of the program that provides a sustainable pediatric surgical service to the small and poor Pacific nation of Vanuatu through the involvement and support of the Pacific Island Project administered by the Royal Australasian College of Surgeons. A needs assessment must be done from the recipient's perspective and can be achieved by collaboration between an external agency and existing local surgeons. The key to a sustainable service is identifying and training high quality young indigenous doctors early and providing mentorship and support, including after their return. A sustainable and viable service requires an adequately resourced position for the new surgeons(s) within a framework of a long term strategic plan for the specialty and adequate infrastructure in place on their return. Development of rapport with government and influencing strategic health priorities is a prerequisite of a new national specialty service. (1) Establishing long term viable pediatric surgical capability can only be achieved through the local health system with local leadership and ownership. (2) Internal capability includes governance, alignment with ministry of health priorities and policies, and effective clinical leadership. (3) Selection of person(s) to be trained is best done early, and he/she must be supported throughout training and

  2. Surgical management of aortopulmonary window: 24 years of experience and lessons learned.

    Science.gov (United States)

    Gowda, Deepak; Gajjar, Trushar; Rao, Jinaga Nageswar; Chavali, Praveen; Sirohi, Aaditya; Pandarinathan, Naveen; Desai, Neelam

    2017-08-01

    Aortopulmonary window represents 0.2-0.3% of all congenital heart lesions. Progressive pulmonary arterial hypertension and its consequences are more common with this anomaly. The purpose of this study was to share 24 years of surgical experience in managing a spectrum of 55 cases of aortopulmonary window, followed up to 17 years in a single institution. This retrospective study was done from November 1991 to November 2015 of 55 patients with aortopulmonary window who underwent successful surgical repair. Age ranged from 5 months to 31 years with 45 children (12 years and younger) and 10 adults (older than 12 years). The male:female ratio was 2.2:1. The mean weight at operation was 14.63 kg (range 3.5-50 kg). An initial diagnosis was obtained from 2D echocardiography, which showed echo dropout in the parasternal short-axis view. Cardiac catheterization and angiography were performed in 54 out of 55 patients. Cardiac catheterization was not done in 1 patient who was 4 months of age. The mean right ventricular systolic pressure (RVSP) was 94 ± 2 mmHg, and the pulmonary artery mean pressure was 68 ± 2 mmHg. The average left to right shunt was 5.2:1, and the pulmonary vascular resistance index in room air was 7.97 ± 0.5 Wood units, whereas after oxygen administration, it declined to 2.0 ± 0.5 Wood units. Four surgical techniques were used based on the size of the communication and the anatomical conditions. There were no early or late deaths. There were no pulmonary hypertensive crises. All patients underwent echocardiography before discharge; none showed a residual shunt. Mild left ventricular dysfunction was seen in 2 patients. This dysfunction regressed with afterload reduction and diuretics on follow-up. All patients were followed up at intervals of 3 months, 1, 5 and 10 years, with the longest follow-up being 17 years. The mean follow-up period was 7 years. At follow-up, all patients were New York Heart Association class I. The mean RVSP

  3. Data-driven methods towards learning the highly nonlinear inverse kinematics of tendon-driven surgical manipulators.

    Science.gov (United States)

    Xu, Wenjun; Chen, Jie; Lau, Henry Y K; Ren, Hongliang

    2017-09-01

    Accurate motion control of flexible surgical manipulators is crucial in tissue manipulation tasks. The tendon-driven serpentine manipulator (TSM) is one of the most widely adopted flexible mechanisms in minimally invasive surgery because of its enhanced maneuverability in torturous environments. TSM, however, exhibits high nonlinearities and conventional analytical kinematics model is insufficient to achieve high accuracy. To account for the system nonlinearities, we applied a data driven approach to encode the system inverse kinematics. Three regression methods: extreme learning machine (ELM), Gaussian mixture regression (GMR) and K-nearest neighbors regression (KNNR) were implemented to learn a nonlinear mapping from the robot 3D position states to the control inputs. The performance of the three algorithms was evaluated both in simulation and physical trajectory tracking experiments. KNNR performed the best in the tracking experiments, with the lowest RMSE of 2.1275 mm. The proposed inverse kinematics learning methods provide an alternative and efficient way to accurately model the tendon driven flexible manipulator. Copyright © 2016 John Wiley & Sons, Ltd.

  4. Learning thoracoscopic lobectomy

    DEFF Research Database (Denmark)

    Petersen, René Horsleben; Hansen, Henrik Jessen

    2010-01-01

    Thoracoscopic (video-assisted thoracoscopic surgery (VATS)) lobectomy is a safe and effective method for treating early-stage lung cancer. Despite this, it is still not widely practised, which could be due to a shallow learning curve. We have evaluated the surgical outcome in a training programme...

  5. A randomized control trial to evaluate the importance of pre-training basic laparoscopic psychomotor skills upon the learning curve of laparoscopic intra-corporeal knot tying.

    Science.gov (United States)

    Molinas, Carlos Roger; Binda, Maria Mercedes; Sisa, Cesar Manuel; Campo, Rudi

    2017-01-01

    Training of basic laparoscopic psychomotor skills improves the acquisition of more advanced laparoscopic tasks, such as laparoscopic intra-corporeal knot tying (LICK). This randomized controlled trial was designed to evaluate whether pre-training of basic skills, as laparoscopic camera navigation (LCN), hand-eye coordination (HEC), and bimanual coordination (BMC), and the combination of the three of them, has any beneficial effect upon the learning curve of LICK. The study was carried out in a private center in Asunción, Paraguay, by 80 medical students without any experience in surgery. Four laparoscopic tasks were performed in the ENCILAP model (LCN, HEC, BMC, and LICK). Participants were allocated to 5 groups (G1-G5). The study was structured in 5 phases. In phase 1, they underwent a base-line test ( T 1 ) for all tasks (1 repetition of each task in consecutive order). In phase 2, participants underwent different training programs (30 consecutive repetitions) for basic tasks according to the group they belong to (G1: none; G2: LCN; G3: HEC; G4: BMC; and G5: LCN, HEC, and BMC). In phase 3, they were tested again ( T 2 ) in the same manner than at T 1 . In phase 4, they underwent a standardized training program for LICK (30 consecutive repetitions). In phase 5, they were tested again ( T 3 ) in the same manner than at T 1 and T 2 . At each repetition, scoring was based on the time taken for task completion system. The scores were plotted and non-linear regression models were used to fit the learning curves to one- and two-phase exponential decay models for each participant (individual curves) and for each group (group curves). The LICK group learning curves fitted better to the two-phase exponential decay model. From these curves, the starting points ( Y 0), the point after HEC training/before LICK training ( Y 1), the Plateau, and the rate constants ( K ) were calculated. All groups, except for G4, started from a similar point ( Y 0). At Y 1, G5 scored already

  6. Learning curve for the management of tyrosine kinase inhibitors as the first line of treatment for patients with metastatic renal cancer.

    Science.gov (United States)

    Lendínez-Cano, G; Osman García, I; Congregado Ruiz, C B; Conde Sánchez, J M; Medina López, R A

    2018-03-07

    To analyse the learning curve for the management of tyrosine kinase inhibitors as the first line of treatment for patients with metastatic renal cancer. We evaluated 32 consecutive patients treated in our department for metastatic renal cancer with tyrosine kinase inhibitors (pazopanib or sunitinib) as first-line treatment between September 2012 and November 2015. We retrospectively analysed this sample. We measured the time to the withdrawal of the first-line treatment, the time to progression and overall survival using Kaplan-Meier curves. The learning curve was analysed with the cumulative sum (CUSUM) methodology. In our series, the median time to the withdrawal of the first-line treatment was 11 months (95% CI 4.9-17.1). The mean time to progression was 30.4 months (95% CI 22.7-38.1), and the mean overall survival was 34.9 months (95% CI 27.8-42). By applying the CUSUM methodology, we obtained a graph for the CUSUM value of the time to withdrawal of the first-line treatment (CUSUM TW), observing 3 well-differentiated phases: phase 1 or initial learning phase (1-15), phase 2 (16-26) in which the management of the drug progressively improved and phase 3 (27-32) of maximum experience or mastery of the management of these drugs. The number of treated patients needed to achieve the proper management of these patients was estimated at 15. Despite the limitations of the sample size and follow-up time, we estimated (in 15 patients) the number needed to reach the necessary experience in the management of these patients with tyrosine kinase inhibitors. We observed no relationship between the time to the withdrawal of the first-line treatment for any cause and progression. Copyright © 2018 AEU. Publicado por Elsevier España, S.L.U. All rights reserved.

  7. Learning curves in highly skilled chess players: a test of the generality of the power law of practice.

    Science.gov (United States)

    Howard, Robert W

    2014-09-01

    The power law of practice holds that a power function best interrelates skill performance and amount of practice. However, the law's validity and generality are moot. Some researchers argue that it is an artifact of averaging individual exponential curves while others question whether the law generalizes to complex skills and to performance measures other than response time. The present study tested the power law's generality to development over many years of a very complex cognitive skill, chess playing, with 387 skilled participants, most of whom were grandmasters. A power or logarithmic function best fit grouped data but individuals showed much variability. An exponential function usually was the worst fit to individual data. Groups differing in chess talent were compared and a power function best fit the group curve for the more talented players while a quadratic function best fit that for the less talented. After extreme amounts of practice, a logarithmic function best fit grouped data but a quadratic function best fit most individual curves. Individual variability is great and the power law or an exponential law are not the best descriptions of individual chess skill development. Copyright © 2014 Elsevier B.V. All rights reserved.

  8. Survey compare team based learning and lecture teaching method, on learning-teaching process nursing student\\'s, in Surgical and Internal Diseases course

    Directory of Open Access Journals (Sweden)

    AA Vaezi

    2015-12-01

    Full Text Available Introduction: The effect of teaching methods on learning process of students will help teachers to improve the quality of teaching by selecting an appropriate method. This study aimed to compare the team- based learning and lecture teaching method on learning-teaching process of nursing students in surgical and internal diseases courses. Method: This quasi-experimental study was carried on the nursing students in the School of Nursing and Midwifery in Yazd and Meybod cities. Studied sample was all of the students in the sixth term in the Faculty of Nursing in Yazd (48 persons and the Faculty of Nursing in Meybod (28 persons. The rate of students' learning through lecture was measured using MCQ tests and teaching based on team-based learning (TBL method was run using MCQ tests (IRAT, GRAT, Appeals and Task group. Therefore, in order to examine the students' satisfaction about the TBL method, a 5-point Likert scale (translated questionnaire (1=completely disagree, 2= disagree, 3=not effective, 4=agree, and 5=completely agree consisted of 22 items was utilized. The reliability and validity of this translated questionnaire was measured. The collected data were analyzed through SPSS 17.0 using descriptive and analytical statistic. Result: The results showed that the mean scores in team-based learning were meaningful in individual assessment (17±84 and assessment group (17.2±1.17. The mean of overall scores in TBL method (17.84±0.98% was higher compared with the lecture teaching method (16±2.31. Most of the students believed that TBL method has improved their interpersonal and group interaction skills (100%. Among them, 97.7% of students mentioned that this method (TBL helped them to understand the course content better. The lowest levels of the satisfaction have related to the continuous learning during lifelong (51.2%. Conclusion: The results of the present study showed that the TBL method led to improving the communication skills, understanding

  9. Placement of central venous port catheters and peripherally inserted central catheters in the routine clinical setting of a radiology department: analysis of costs and intervention duration learning curve.

    Science.gov (United States)

    Rotzinger, Roman; Gebauer, Bernhard; Schnapauff, Dirk; Streitparth, Florian; Wieners, Gero; Grieser, Christian; Freyhardt, Patrick; Hamm, Bernd; Maurer, Martin H

    2017-12-01

    Background Placement of central venous port catheters (CVPS) and peripherally inserted central catheters (PICC) is an integral component of state-of-the-art patient care. In the era of increasing cost awareness, it is desirable to have more information to comprehensively assess both procedures. Purpose To perform a retrospective analysis of interventional radiologic implantation of CVPS and PICC lines in a large patient population including a cost analysis of both methods as well as an investigation the learning curve in terms of the interventions' durations. Material and Methods All CVPS and PICC line related interventions performed in an interventional radiology department during a three-year period from January 2011 to December 2013 were examined. Documented patient data included sex, venous access site, and indication for CVPS or PICC placement. A cost analysis including intervention times was performed based on the prorated costs of equipment use, staff costs, and expenditures for disposables. The decrease in intervention duration in the course of time conformed to the learning curve. Results In total, 2987 interventions were performed by 16 radiologists: 1777 CVPS and 791 PICC lines. An average implantation took 22.5 ± 0.6 min (CVPS) and 10.1 ± 0.9 min (PICC lines). For CVPS, this average time was achieved by seven radiologists newly learning the procedures after performing 20 CVPS implantations. Total costs per implantation were €242 (CVPS) and €201 (PICC lines). Conclusion Interventional radiologic implantations of CVPS and PICC lines are well-established procedures, easy to learn by residents, and can be implanted at low costs.

  10. Underlying mechanisms of mistreatment in the surgical learning environment: A thematic analysis of medical student perceptions.

    Science.gov (United States)

    Brandford, Elena; Hasty, Brittany; Bruce, Janine S; Bereknyei Merrell, Sylvia; Shipper, Edward S; Lin, Dana T; Lau, James N

    2018-02-01

    Medical students experience more psychological distress than the general population. One contributing factor is mistreatment. This study aims to understand the mechanisms of mistreatment as perceived by medical students. Students completed anonymous surveys during the first and last didactic session of their surgery clerkship in which they defined and gave examples of mistreatment. Team-based thematic analysis was performed on responses. Between January 2014 and June 2016, 240 students participated in the surgery clerkship. Eighty-nine percent of students completed a survey. Themes observed included (1) Obstruction of Students' Learning, (2) Exploitation of Student Vulnerability, (3) Exclusion from the Medical Team, and (4) Contextual Amplifiers of Mistreatment Severity. The themes observed in this study improve our understanding of the students' perspective on mistreatment as it relates to their role in the clinical learning context, which can serve as a starting point for interventions that ultimately improve students' experiences in the clinical setting. Copyright © 2017 Elsevier Inc. All rights reserved.

  11. Is there a learning curve for the TVT-O procedure? A prospective single-surgeon study of 372 consecutive cases.

    Science.gov (United States)

    Serati, Maurizio; Bogani, Giorgio; Braga, Andrea; Sorice, Paola; Salvatore, Stefano; Uccella, Stefano; Ghezzi, Fabio

    2015-03-01

    To evaluate for the first time in the literature the learning curve of Inside-out transobturator tape (TVT-O™). A prospective observational study was conducted in a tertiary reference center. Consecutive women treated by TVT-O™ performed by one surgeon were included. Data regarding subjective, objective cure rates, and adverse events were collected. Trends, over the number of procedures, were estimated using assay analyses. Number of procedures and variables were interpolating in standard curves using linear lines. Three hundred and seventy two procedures were included. Postoperative pain levels decreased with the increase in the level of expertise (pain levels: 1-day: from 6.6 (±3.3) to 4.3 (±3.1); 95%CI: -0.01603 to 0.001235, p=0.04; 2-day: from 5.6 (±4.1) to 3.6 (±3.7); 95%CI: -0.02092 to -0.002497, p=0.01; 12-month: from 0.1 (±0.7) to 0 (±0); 95%CI: -0.001814 to 0.05019, p=0.07). Overall, objective cure rate was achieved in 93.5% of patients. Additionally, 88.2% and 88.7% patients reported "much better" feeling at PGI-I scale and 80% reduction in UDI score, respectively. We observed, that delta ICIQ-sf (from 12 (±8.7) to 14 (±6.0); p=0.04) and delta-UDI (from 91% to 97%; p=0.04) improved over the time. TVT-O procedure offers excellent outcomes with high objective and subjective cure rates and low complications rate, even at the beginning of the surgeon's learning curve. However, a high experience of the surgeon could significantly improve the subjective cure rate and could reduce postoperative the groin pain. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

  12. How Good Is Good: Improved Tracking and Managing of Safety Goals, Performance Indicators, Production Targets and Significant Events Using Learning Curves

    International Nuclear Information System (INIS)

    Duffey, Rommey B.; Saull, John W.

    2002-01-01

    We show a new way to track and measure safety and performance using learning curves derived on a mathematical basis. When unusual or abnormal events occur in plants and equipment, the regulator and good management practice requires they be reported, investigated, understood and rectified. In addition to reporting so-called 'significant events', both management and the regulator often set targets for individual and collective performance, which are used for both reward and criticism. For almost completely safe systems, like nuclear power plants, commercial aircraft and chemical facilities, many parameters are tracked and measured. Continuous improvement has to be demonstrated, as well as meeting reduced occurrence rates, which are set as management goals or targets. This process usually takes the form of statistics for availability of plant and equipment, forced or unplanned maintenance outage, loss of safety function, safety or procedural violations, etc. These are often rolled up into a set of so-called 'Performance Indicators' as measures of how well safety and operation is being managed at a given facility. The overall operating standards of an industry are also measured. A whole discipline is formed of tracking, measuring, reporting, managing and understanding the plethora of indicators and data. Decreasing occurrence rates and meeting or exceeding goals are seen and rewarded as virtues. Managers and operators need to know how good is their safety management system that has been adopted and used (and paid for), and whether it can itself be improved. We show the importance of accumulated experience in correctly measuring and tracking the decreasing event and error rates speculating a finite minimum rate. We show that the rate of improvement constitutes a measurable 'learning curve', and the attainment of the goals and targets can be affected by the adopted measures. We examine some of the available data on significant events, reportable occurrences, and loss of

  13. Surgical Assisting

    Science.gov (United States)

    ... instruction, including: Microbiology Pathophysiology Pharmacology Anatomy and physiology Medical terminology Curriculum . Course content includes: Advanced surgical anatomy Surgical microbiology Surgical pharmacology Anesthesia methods and agents Bioscience Ethical ...

  14. Surgical innovation: the ethical agenda: A systematic review.

    Science.gov (United States)

    Broekman, Marike L; Carrière, Michelle E; Bredenoord, Annelien L

    2016-06-01

    The aim of the present article was to systematically review the ethics of surgical innovation and introduce the components of the learning health care system to guide future research and debate on surgical innovation.Although the call for evidence-based practice in surgery is increasingly high on the agenda, most surgeons feel that the format of the randomized controlled trial is not suitable for surgery. Innovation in surgery has aspects of, but should be distinguished from both research and clinical care and raises its own ethical challenges.To answer the question "What are the main ethical aspects of surgical innovation?", we systematically searched PubMed and Embase. Papers expressing an opinion, point of view, or position were included, that is, normative ethical papers.We included 59 studies discussing ethical aspects of surgical innovation. These studies discussed 4 major themes: oversight, informed consent, learning curve, and vulnerable patient groups. Although all papers addressed the ethical challenges raised by surgical innovation, surgeons hold no uniform view of surgical innovation, and there is no agreement on the distinction between innovation and research. Even though most agree to some sort of oversight, they offer different alternatives ranging from the formation of new surgical innovation committees to establishing national registries. Most agree that informed consent is necessary for innovative procedures and that surgeons should be adequately trained to assure their competence to tackle the learning curve problem. All papers agree that in case of vulnerable patients, alternatives must be found for the informed consent procedure.We suggest that the concept of the learning health care system might provide guidance for thinking about surgical innovation. The underlying rationale of the learning health care system is to improve the quality of health care by embedding research within clinical care. Two aspects of a learning health care system might

  15. Surgical simulation in orthopaedic skills training.

    Science.gov (United States)

    Atesok, Kivanc; Mabrey, Jay D; Jazrawi, Laith M; Egol, Kenneth A

    2012-07-01

    Mastering rapidly evolving orthopaedic surgical techniques requires a lengthy period of training. Current work-hour restrictions and cost pressures force trainees to face the challenge of acquiring more complex surgical skills in a shorter amount of time. As a result, alternative methods to improve the surgical skills of orthopaedic trainees outside the operating room have been developed. These methods include hands-on training in a laboratory setting using synthetic bones or cadaver models as well as software tools and computerized simulators that enable trainees to plan and simulate orthopaedic operations in a three-dimensional virtual environment. Laboratory-based training offers potential benefits in the development of basic surgical skills, such as using surgical tools and implants appropriately, achieving competency in procedures that have a steep learning curve, and assessing already acquired skills while minimizing concerns for patient safety, operating room time, and financial constraints. Current evidence supporting the educational advantages of surgical simulation in orthopaedic skills training is limited. Despite this, positive effects on the overall education of orthopaedic residents, and on maintaining the proficiency of practicing orthopaedic surgeons, are anticipated.

  16. Abortion - surgical

    Science.gov (United States)

    Suction curettage; Surgical abortion; Elective abortion - surgical; Therapeutic abortion - surgical ... Surgical abortion involves dilating the opening to the uterus (cervix) and placing a small suction tube into the uterus. ...

  17. Análise de conglomerados em curvas de aprendizado para formação de agrupamentos homogêneos de trabalhadores Cluster analysis of learning curves for grouping workers with homogeneous learning profiles

    Directory of Open Access Journals (Sweden)

    Renato Eduardo Stroieke

    2012-01-01

    Full Text Available Em diversos setores da indústria é desejado que trabalhadores reunidos em uma estação de trabalho apresentem perfil de aprendizado similar. O presente artigo apresenta um método de agrupamento de trabalhadores utilizando modelagem por curva de aprendizado e técnicas de clusterização. O método modela dados de desempenho de trabalhadores por intermédio de diversos modelos de curvas de aprendizado; os parâmetros de aprendizado dos modelos testados permitem predizer o desempenho dos trabalhadores em intervalos de tempo pré-determinados. Os valores preditos são agrupados através de ferramentas de clusterização. O maior índice de ajuste (IA, gerado a partir do Silhouette Index e do coeficiente de determinação, indica o modelo de curva mais consistente em termos de aderência aos dados e qualidade de agrupamento de perfis de aprendizado. Ao ser aplicado em dados de uma indústria de calçados, o método gerou agrupamentos consistentes de trabalhadores com base nos distintos perfis de aprendizado.In many industrial segments, it is desirable to allocate workers with similar learning profiles in the same workstation. This paper presents a method that groups workers based on learning curve modeling and clustering techniques. Workers' performance data are modeled through several learning curve models; learning parameters allow for workers' performance prediction at intervals of predetermined time. The predicted values are then grouped by clustering techniques. The largest Adjustment Index (AI, derived from the Silhouette Index and Coefficient of Determination, indicates the model yielding superior adherence to data and better clustering of learning profiles. When applied to a shoe manufacturing process, the method generated consistent groups of workers based on their learning profiles.

  18. Analysis on learning curves of end-use appliances for the establishment of price-sensitivity load model in competitive electricity market

    Energy Technology Data Exchange (ETDEWEB)

    Hwang, Sung Wook; Kim, Jung Hoon [Hongik University (Korea); Song, Kyung Bin [Keimyung University (Korea); Choi, Joon Young [Jeonju University (Korea)

    2001-07-01

    The change of the electricity charge from cost base to price base due to the introduction to the electricity market competition causes consumer to choose a variety of charge schemes and a portion of loads to be affected by this change. Besides, it is required the index that consolidate the price volatility experienced on the power exchange with gaming and strategic bidding by suppliers to increase profits. Therefore, in order to find a mathematical model of the sensitively-responding to-price loads, the price-sensitive load model is needed. And the development of state-of- the-art technologies affects the electricity price, so the diffusion of high-efficient end-uses and these price affect load patterns. This paper shows the analysis on learning curves algorithms which is used to investigate the correlation of the end-uses' price and load patterns. (author). 6 refs., 4 figs., 4 tabs.

  19. Water exchange method for colonoscopy: learning curve of an experienced colonoscopist in a U.S. community practice setting.

    Science.gov (United States)

    Fischer, Leonard S; Lumsden, Antoinette; Leung, Felix W

    2012-07-01

    Water exchange colonoscopy has been reported to reduce examination discomfort and to provide salvage cleansing in unsedated or minimally sedated patients. The prolonged insertion time and perceived difficulty of insertion associated with water exchange have been cited as a barrier to its widespread use. To assess the feasibility of learning and using the water exchange method of colonoscopy in a U.S. community practice setting. Quality improvement program in nonacademic community endoscopy centers. Patients undergoing sedated diagnostic, surveillance, or screening colonoscopy. After direct coaching by a knowledgeable trainer, an experienced colonoscopist initiated colonoscopy using the water method. Whenever >5 min elapsed without advancing the colonoscope, conversion to air insufflation was made to ensure timely completion of the examination. Water Method Intention-to-treat (ITT) cecal intubation rate (CIR). Female patients had a significantly higher rate of past abdominal surgery and a significantly lower ITTCIR. The ITTCIR showed a progressive increase over time in both males and females to 85-90%. Mean insertion time was maintained at 9 to 10 min. The overall CIR was 99%. Use of water exchange did not preclude cecal intubation upon conversion to usual air insufflation in sedated patients examined by an experienced colonoscopist. With practice ITTCIR increased over time in both male and female patients. Larger volumes of water exchanged were associated with higher ITTCIR and better quality scores of bowel preparation. The data suggest that learning water exchange by a busy colonoscopist in a community practice setting is feasible and outcomes conform to accepted quality standards.

  20. Machine learning classification of surgical pathology reports and chunk recognition for information extraction noise reduction.

    Science.gov (United States)

    Napolitano, Giulio; Marshall, Adele; Hamilton, Peter; Gavin, Anna T

    2016-06-01

    Machine learning techniques for the text mining of cancer-related clinical documents have not been sufficiently explored. Here some techniques are presented for the pre-processing of free-text breast cancer pathology reports, with the aim of facilitating the extraction of information relevant to cancer staging. The first technique was implemented using the freely available software RapidMiner to classify the reports according to their general layout: 'semi-structured' and 'unstructured'. The second technique was developed using the open source language engineering framework GATE and aimed at the prediction of chunks of the report text containing information pertaining to the cancer morphology, the tumour size, its hormone receptor status and the number of positive nodes. The classifiers were trained and tested respectively on sets of 635 and 163 manually classified or annotated reports, from the Northern Ireland Cancer Registry. The best result of 99.4% accuracy - which included only one semi-structured report predicted as unstructured - was produced by the layout classifier with the k nearest algorithm, using the binary term occurrence word vector type with stopword filter and pruning. For chunk recognition, the best results were found using the PAUM algorithm with the same parameters for all cases, except for the prediction of chunks containing cancer morphology. For semi-structured reports the performance ranged from 0.97 to 0.94 and from 0.92 to 0.83 in precision and recall, while for unstructured reports performance ranged from 0.91 to 0.64 and from 0.68 to 0.41 in precision and recall. Poor results were found when the classifier was trained on semi-structured reports but tested on unstructured. These results show that it is possible and beneficial to predict the layout of reports and that the accuracy of prediction of which segments of a report may contain certain information is sensitive to the report layout and the type of information sought. Copyright

  1. Assessing Technical Performance and Determining the Learning Curve in Cleft Palate Surgery Using a High-Fidelity Cleft Palate Simulator.

    Science.gov (United States)

    Podolsky, Dale J; Fisher, David M; Wong Riff, Karen W; Szasz, Peter; Looi, Thomas; Drake, James M; Forrest, Christopher R

    2018-06-01

    This study assessed technical performance in cleft palate repair using a newly developed assessment tool and high-fidelity cleft palate simulator through a longitudinal simulation training exercise. Three residents performed five and one resident performed nine consecutive endoscopically recorded cleft palate repairs using a cleft palate simulator. Two fellows in pediatric plastic surgery and two expert cleft surgeons also performed recorded simulated repairs. The Cleft Palate Objective Structured Assessment of Technical Skill (CLOSATS) and end-product scales were developed to assess performance. Two blinded cleft surgeons assessed the recordings and the final repairs using the CLOSATS, end-product scale, and a previously developed global rating scale. The average procedure-specific (CLOSATS), global rating, and end-product scores increased logarithmically after each successive simulation session for the residents. Reliability of the CLOSATS (average item intraclass correlation coefficient (ICC), 0.85 ± 0.093) and global ratings (average item ICC, 0.91 ± 0.02) among the raters was high. Reliability of the end-product assessments was lower (average item ICC, 0.66 ± 0.15). Standard setting linear regression using an overall cutoff score of 7 of 10 corresponded to a pass score for the CLOSATS and the global score of 44 (maximum, 60) and 23 (maximum, 30), respectively. Using logarithmic best-fit curves, 6.3 simulation sessions are required to reach the minimum standard. A high-fidelity cleft palate simulator has been developed that improves technical performance in cleft palate repair. The simulator and technical assessment scores can be used to determine performance before operating on patients.

  2. From the curve of the snake, and the scene of the crocodile: musings on learning and losing space, place and body

    Directory of Open Access Journals (Sweden)

    Susanne Gannon

    2012-12-01

    Full Text Available Where else can educational research begin and end, if not with the body of the researcher, if not with the particular material/ corporeal/ affective assemblages that this body is and has been part of? This paper traces the mutual constitution of bodies, identities and landscapes through memory as the body of this educator travels through multiple scenes of geo-spatial-temporal movement, and down the east coast of Australia. This movement parallels the movement from being a school teacher to becoming an academic. Throughout the paper landscape is foregrounded, and the body in landscape is evoked through poetic and literary modes of writing around the themes of learning and losing. The body in landscape is not merely the body of the writer. Other bodies in the landscape include ‘the curve of the snake’ - the row of protective hills that were said to protect her tropical home from cyclones – and the ‘scene of the crocodile’ – the rock that hung over the valley she passed on her way to school that she had learned of from Indigenous teachers. The political and ethical consequences of memory work, of body and place writing, and of genres of writing in educational research, are also considered. The paper argues for an embodied and reflexive literacy of place that incorporates multiple modes of knowing, being and writing.

  3. Supervised Learning of Two-Layer Perceptron under the Existence of External Noise — Learning Curve of Boolean Functions of Two Variables in Tree-Like Architecture —

    Science.gov (United States)

    Uezu, Tatsuya; Kiyokawa, Shuji

    2016-06-01

    We investigate the supervised batch learning of Boolean functions expressed by a two-layer perceptron with a tree-like structure. We adopt continuous weights (spherical model) and the Gibbs algorithm. We study the Parity and And machines and two types of noise, input and output noise, together with the noiseless case. We assume that only the teacher suffers from noise. By using the replica method, we derive the saddle point equations for order parameters under the replica symmetric (RS) ansatz. We study the critical value αC of the loading rate α above which the learning phase exists for cases with and without noise. We find that αC is nonzero for the Parity machine, while it is zero for the And machine. We derive the exponents barβ of order parameters expressed as (α - α C)bar{β} when α is near to αC. Furthermore, in the Parity machine, when noise exists, we find a spin glass solution, in which the overlap between the teacher and student vectors is zero but that between student vectors is nonzero. We perform Markov chain Monte Carlo simulations by simulated annealing and also by exchange Monte Carlo simulations in both machines. In the Parity machine, we study the de Almeida-Thouless stability, and by comparing theoretical and numerical results, we find that there exist parameter regions where the RS solution is unstable, and that the spin glass solution is metastable or unstable. We also study asymptotic learning behavior for large α and derive the exponents hat{β } of order parameters expressed as α - hat{β } when α is large in both machines. By simulated annealing simulations, we confirm these results and conclude that learning takes place for the input noise case with any noise amplitude and for the output noise case when the probability that the teacher's output is reversed is less than one-half.

  4. Anxiety in veterinary surgical students

    DEFF Research Database (Denmark)

    Langebæk, Rikke; Eika, Berit; Jensen, Asger Lundorff

    2012-01-01

    The surgical educational environment is potentially stressful and this can negatively affect students' learning. The aim of this study was to investigate whether veterinary students' level of anxiety is higher in a surgical course than in a non-surgical course and if pre-surgical training...... in a Surgical Skills Lab (SSL) has an anxiety reducing effect. Investigations were carried out as a comparative study and a parallel group study. Potential participants were fourth-year veterinary students who attended a surgical course (Basic Surgical Skills) and a non-surgical course (Clinical Examination...... and 28 students from 2010). Our results show that anxiety levels in veterinary students are significantly higher in a surgical course than in a non-surgical course (p...

  5. Post-operative 3D CT feedback improves accuracy and precision in the learning curve of anatomic ACL femoral tunnel placement.

    Science.gov (United States)

    Sirleo, Luigi; Innocenti, Massimo; Innocenti, Matteo; Civinini, Roberto; Carulli, Christian; Matassi, Fabrizio

    2018-02-01

    tunnel placement in order to obtain anatomic ACL reconstruction and helps to reduce also arthroscopic time and learning curve. For clinical relevance, trainee-surgeons should use feedback from post-operative 3DCT to learn anatomic ACL femoral tunnel placement and apply it appropriately. Consecutive case series, Level IV.

  6. Surgical lighting

    NARCIS (Netherlands)

    Knulst, A.J.

    2017-01-01

    The surgical light is an important tool for surgeons to create and maintain good visibility on the surgical task. Chapter 1 gives background to the field of (surgical) lighting and related terminology. Although the surgical light has been developed strongly since its introduction a long time ago,

  7. Do We Need to Clamp the Renal Hilum Liberally during the Initial Phase of the Learning Curve of Robot-Assisted Nephron-Sparing Surgery?

    Directory of Open Access Journals (Sweden)

    Ömer Acar

    2014-01-01

    Full Text Available Objective. We aimed to compare the results of our initial robot-assisted nephron-sparing surgeries (RANSS performed with or without hilar clamping. Material and Method. Charts of the initial RANSSs (n=44, which were performed by a single surgeon, were retrospectively reviewed. R.E.N.A.L. nephrometry system, modified Clavien classification, and M.D.R.D. equation were used to record tumoral complexity, complications, and estimated glomerular filtration rate (eGFR, respectively. Outcomes of the clamped (group 1, n=14 versus off-clamp (group 2, n=30 RANSSs were compared. Results. The difference between the two groups was insignificant regarding mean patient age, mean tumor size, and mean R.E.N.A.L. nephrometry score. Mean operative time, mean estimated blood loss amount, and mean length of hospitalization were similar between groups. A total of 4 patients in each group suffered 11 Clavien grade ≥2 complications early postoperatively. Open conversion rates were similar. The difference between the 2 groups in terms of the mean postoperative change in eGFR was insignificant. We did not encounter any local recurrence after a mean follow-up of 18.9 months. Conclusions. Creating warm-ischemic conditions during RANSS should not be a liberal decision, even in the initial phases of the learning curve for a highly experienced open surgeon.

  8. The Climate Change Learning Curve

    OpenAIRE

    Andrew J. Leach

    2004-01-01

    The key element in the tension between those who believe climate change is an issue and those who do not is essentially the question of whether we are merely in a long period of shock-induced above average temperatures or if we have led to this increase in temperatures by anthropogenic carbon emissions. The model proposed in this paper allows for a model in which we weigh observations on temperature against the potential that these are generated by a combination of uncertain parameters; namel...

  9. Preclinical endoscopic training using a part-task simulator: learning curve assessment and determination of threshold score for advancement to clinical endoscopy.

    Science.gov (United States)

    Jirapinyo, Pichamol; Abidi, Wasif M; Aihara, Hiroyuki; Zaki, Theodore; Tsay, Cynthia; Imaeda, Avlin B; Thompson, Christopher C

    2017-10-01

    Preclinical simulator training has the potential to decrease endoscopic procedure time and patient discomfort. This study aims to characterize the learning curve of endoscopic novices in a part-task simulator and propose a threshold score for advancement to initial clinical cases. Twenty novices with no prior endoscopic experience underwent repeated endoscopic simulator sessions using the part-task simulator. Simulator scores were collected; their inverse was averaged and fit to an exponential curve. The incremental improvement after each session was calculated. Plateau was defined as the session after which incremental improvement in simulator score model was less than 5%. Additionally, all participants filled out questionnaires regarding simulator experience after sessions 1, 5, 10, 15, and 20. A visual analog scale and NASA task load index were used to assess levels of comfort and demand. Twenty novices underwent 400 simulator sessions. Mean simulator scores at sessions 1, 5, 10, 15, and 20 were 78.5 ± 5.95, 176.5 ± 17.7, 275.55 ± 23.56, 347 ± 26.49, and 441.11 ± 38.14. The best fit exponential model was [time/score] = 26.1 × [session #] -0.615 ; r 2  = 0.99. This corresponded to an incremental improvement in score of 35% after the first session, 22% after the second, 16% after the third and so on. Incremental improvement dropped below 5% after the 12th session corresponding to the predicted score of 265. Simulator training was related to higher comfort maneuvering an endoscope and increased readiness for supervised clinical endoscopy, both plateauing between sessions 10 and 15. Mental demand, physical demand, and frustration levels decreased with increased simulator training. Preclinical training using an endoscopic part-task simulator appears to increase comfort level and decrease mental and physical demand associated with endoscopy. Based on a rigorous model, we recommend that novices complete a minimum of 12 training

  10. LCC: Light Curves Classifier

    Science.gov (United States)

    Vo, Martin

    2017-08-01

    Light Curves Classifier uses data mining and machine learning to obtain and classify desired objects. This task can be accomplished by attributes of light curves or any time series, including shapes, histograms, or variograms, or by other available information about the inspected objects, such as color indices, temperatures, and abundances. After specifying features which describe the objects to be searched, the software trains on a given training sample, and can then be used for unsupervised clustering for visualizing the natural separation of the sample. The package can be also used for automatic tuning parameters of used methods (for example, number of hidden neurons or binning ratio). Trained classifiers can be used for filtering outputs from astronomical databases or data stored locally. The Light Curve Classifier can also be used for simple downloading of light curves and all available information of queried stars. It natively can connect to OgleII, OgleIII, ASAS, CoRoT, Kepler, Catalina and MACHO, and new connectors or descriptors can be implemented. In addition to direct usage of the package and command line UI, the program can be used through a web interface. Users can create jobs for ”training” methods on given objects, querying databases and filtering outputs by trained filters. Preimplemented descriptors, classifier and connectors can be picked by simple clicks and their parameters can be tuned by giving ranges of these values. All combinations are then calculated and the best one is used for creating the filter. Natural separation of the data can be visualized by unsupervised clustering.

  11. Learning curve of sentinel lymph nodes in early breast cancer at the Teaching Hospital 'Hospital das Clinicas' in Belo Horizonte, MG

    International Nuclear Information System (INIS)

    Homma, L.A.H.; Campos, T.P.R.; Silva, S.Z.C.; Siqueira, C.F.; Lima, C.F.

    2007-01-01

    The research of the sentinel lymph node in early breast cancer, an already worldwide established method, was standardized at the teaching hospital 'Hospital das Clinicas' in Belo Horizonte (MG, Brazil). This standardization was carried out from December 2000 through December 2002, in which 39 patients were included in a learning curve and method validation. The applied methodology is based on the combination of a lymphoscintillography and the blue stain. A periareolar colloid 99m Tc injection was given 24 hours before the surgery. The blue dye was injected in the peritumoral region during the surgery. The sentinel lymph node was identified by the blue color pattern of the lymph node and by the use of a portable gamma probe detector. Radioactive contamination was evaluated before, during and after the surgery. The measurement of the radioactivity of the breast area was taken by using a GM detector and an ionization chamber on a humid piece of gauze (passed on the breast area), from which the radioactivity was recorded as well as the gloves used during the surgery, and the gauzes with contaminated blood. The sentinel lymph node identification rate was found to be 95%, there was a false negative rate of 4,8% and a predictive negative value (PNV) of 94%. The identification figures, the predictive negative value and the false negative rate were similar to the figures found in technical literature. The technique of the biopsy of the sentinel lymph node (BSL) is the method chosen for staging patients with invasive breast cancer and with clinically negative results for the armpit. The combined method using radio-colloid and the stain is the most indicated. There is a minimum radio isotopic contamination and there is scarcely any danger for the patient or the medical staff involved in the procedure. (author)

  12. Tracking-by-detection of surgical instruments in minimally invasive surgery via the convolutional neural network deep learning-based method.

    Science.gov (United States)

    Zhao, Zijian; Voros, Sandrine; Weng, Ying; Chang, Faliang; Li, Ruijian

    2017-12-01

    Worldwide propagation of minimally invasive surgeries (MIS) is hindered by their drawback of indirect observation and manipulation, while monitoring of surgical instruments moving in the operated body required by surgeons is a challenging problem. Tracking of surgical instruments by vision-based methods is quite lucrative, due to its flexible implementation via software-based control with no need to modify instruments or surgical workflow. A MIS instrument is conventionally split into a shaft and end-effector portions, while a 2D/3D tracking-by-detection framework is proposed, which performs the shaft tracking followed by the end-effector one. The former portion is described by line features via the RANSAC scheme, while the latter is depicted by special image features based on deep learning through a well-trained convolutional neural network. The method verification in 2D and 3D formulation is performed through the experiments on ex-vivo video sequences, while qualitative validation on in-vivo video sequences is obtained. The proposed method provides robust and accurate tracking, which is confirmed by the experimental results: its 3D performance in ex-vivo video sequences exceeds those of the available state-of -the-art methods. Moreover, the experiments on in-vivo sequences demonstrate that the proposed method can tackle the difficult condition of tracking with unknown camera parameters. Further refinements of the method will refer to the occlusion and multi-instrumental MIS applications.

  13. Surgical smoke.

    Science.gov (United States)

    Fan, Joe King-Man; Chan, Fion Siu-Yin; Chu, Kent-Man

    2009-10-01

    Surgical smoke is the gaseous by-product formed during surgical procedures. Most surgeons, operating theatre staff and administrators are unaware of its potential health risks. Surgical smoke is produced by various surgical instruments including those used in electrocautery, lasers, ultrasonic scalpels, high speed drills, burrs and saws. The potential risks include carbon monoxide toxicity to the patient undergoing a laparoscopic operation, pulmonary fibrosis induced by non-viable particles, and transmission of infectious diseases like human papilloma virus. Cytotoxicity and mutagenicity are other concerns. Minimisation of the production of surgical smoke and modification of any evacuation systems are possible solutions. In general, a surgical mask can provide more than 90% protection to exposure to surgical smoke; however, in most circumstances it cannot provide air-tight protection to the user. An at least N95 grade or equivalent respirator offers the best protection against surgical smoke, but whether such protection is necessary is currently unknown.

  14. Lagrangian Curves on Spectral Curves of Monopoles

    International Nuclear Information System (INIS)

    Guilfoyle, Brendan; Khalid, Madeeha; Ramon Mari, Jose J.

    2010-01-01

    We study Lagrangian points on smooth holomorphic curves in TP 1 equipped with a natural neutral Kaehler structure, and prove that they must form real curves. By virtue of the identification of TP 1 with the space LE 3 of oriented affine lines in Euclidean 3-space, these Lagrangian curves give rise to ruled surfaces in E 3 , which we prove have zero Gauss curvature. Each ruled surface is shown to be the tangent lines to a curve in E 3 , called the edge of regression of the ruled surface. We give an alternative characterization of these curves as the points in E 3 where the number of oriented lines in the complex curve Σ that pass through the point is less than the degree of Σ. We then apply these results to the spectral curves of certain monopoles and construct the ruled surfaces and edges of regression generated by the Lagrangian curves.

  15. What have we learned from reporting safety incidents in the Surgical Block?: Cross-sectional descriptive study of two-years of activity of a multidisciplinary analytical group.

    Science.gov (United States)

    Caba Barrientos, F; Rodríguez Morillo, A; Galisteo Domínguez, R; Del Nozal Nalda, M; Almeida González, C V; Echevarría Moreno, M

    2018-05-01

    Incident Reporting Systems (IRS) are considered a tool that facilitates learning and safety culture. Using the experience gained with SENSAR, we evaluated the feasibility and the activity of a multidisciplinary group analyzing incidents in the surgical patient notified to a general community system, that of the Observatory for Patient Safety (OPS). Cross-sectional observational study planned for two years. After training in the analysis, a multidisciplinary group was created in terms of specialties and professional categories, which would analyze the incidents in the surgical patient notified to the OPS. Incidents are classified and their circumstances analyzed. Between March 2015 and 2017, 95 incidents were reported (4 by non-professionals). Doctors reported more than nurses, at 54 (56.84%) vs. 37 (38.94%). The anaesthesia unit reported most at 46 (48.42%) (P=.025). The types of incidents mainly related to the care procedure (30.52%); to the preoperative period (42.10%); and to the place, the surgical area (48.42%). Significant differences were detected according to the origin of the notifier (P=.03). No harm, or minor morbidity, constituted 88% of the incidents. Errors were identified in 79%. The analysis of the incidents directed the measures to be taken. The activity undertaken by the multidisciplinary analytical group during the period of study facilitated knowledge of the system among the professionals and enabled the identification of areas for improvement in the Surgical Block at different levels. Copyright © 2017 Sociedad Española de Anestesiología, Reanimación y Terapéutica del Dolor. Publicado por Elsevier España, S.L.U. All rights reserved.

  16. The effect of surgical resident learning style preferences on American Board of Surgery In-training Examination scores.

    Science.gov (United States)

    Kim, Roger H; Gilbert, Timothy; Ristig, Kyle

    2015-01-01

    There is a growing body of literature that suggests that learners assimilate information differently, depending on their preferred learning style. The VARK model categorizes learners as visual (V), aural (A), read/write (R), kinesthetic (K), or multimodal (MM). We hypothesized that resident VARK learning style preferences and American Board of Surgery In-Training Examination (ABSITE) performance are associated. The Fleming VARK learning styles inventory was administered to all general surgery residents at a university hospital-based program each year to determine their preferred learning style. Resident scores from the 2012 and 2013 ABSITE were examined to identify any correlation with learning style preferences. Over a 2-year period, residents completed 53 VARK inventory assessments. Most (51%) had a multimodal preference. Dominant aural and read/write learners had the lowest and highest mean ABSITE scores, respectively (p = 0.03). Residents with dominant read/write learning preferences perform better on the ABSITE than their peers did, whereas residents with dominant aural learning preferences underperform on the ABSITE. This may reflect an inherent and inadvertent bias of the examination against residents who prefer to learn via aural modalities. Copyright © 2015 Association of Program Directors in Surgery. Published by Elsevier Inc. All rights reserved.

  17. The new courses of ethanol production in Brazil: an analysis from learning curves; Os novos rumos da producao de alcool combustivel no Brasil: uma analise a partir de curvas de aprendizagem

    Energy Technology Data Exchange (ETDEWEB)

    Pereira, Junior, Amaro Olimpio [Empresa de Pesquisa Energetica (EPE), Brasilia, DF (Brazil); Pereira, Andre Santos [Centre de Recherche sur Environement et Developement (CIRED), Paris (France); Mendonca, Marco Aurelio [Instituto de Pesquisa Economica Aplicada (IPEA), Brasilia, DF (Brazil); Costa, Ricardo Cunha da [Universidade Federal do Rio de Janeiro (PPE/COPPE/UFRJ), RJ (Brazil). Coordenacao do Programa de Pos-Graduacao em Engenharia. Programa de Pos-Graduacao em Planejamento Energetico

    2008-07-01

    PROALCOOL is known internationally as the most successful biofuel promotion program. Prior analysis of the effectiveness of such a program is fundamental to formulation of public policy, not only in the area of energy, but in all sectors of the economy. The article applies learning curve methodology to evaluate the ethanol market in Brazil in order to give an idea about the effort, in terms of investments, required for its advancement. (author)

  18. Assessment of minimally invasive surgical skills of pre-medical students: What can we learn from future learners?

    Science.gov (United States)

    Borahay, Mostafa A; Jackson, Mary; Tapısız, Omer L; Lyons, Elizabeth; Patel, Pooja R; Nassar, Ramsey; Kılıç, Gökhan Sami

    2014-01-01

    Knowledge of baseline laparoscopic and robotic surgical skills of future learners is essential to develop teaching strategies that best fit them. The objectives of this study are to determine baseline laparoscopic and robotic skills of high school and college students and compare them to those of current obstetrics and gynecology residents. A cross-sectional (Class II-2) pilot study. Laparoscopic and robotic surgical skills of college and high (secondary) school students were evaluated using simulators and compared to those of obstetrics and gynecology residents. In addition, questionnaire data were collected regarding video game playing and computer use. A total of 17 students, both high school (n=9) and college (n=8), in addition to 11 residents, completed the study. Overall, students performed comparably to the residents in simple exercises (p>.05). However, students took significantly longer time to complete complex exercises (p=.001). Finally, students played video games significantly more than residents (pskill set. This difference may be related to improved hand-eye coordination, possibly due to playing video games. The results of this pilot study should spur more research into surgical teaching strategies.

  19. The New Keynesian Phillips Curve

    DEFF Research Database (Denmark)

    Ólafsson, Tjörvi

    This paper provides a survey on the recent literature on the new Keynesian Phillips curve: the controversies surrounding its microfoundation and estimation, the approaches that have been tried to improve its empirical fit and the challenges it faces adapting to the open-economy framework. The new......, learning or state-dependant pricing. The introduction of openeconomy factors into the new Keynesian Phillips curve complicate matters further as it must capture the nexus between price setting, inflation and the exchange rate. This is nevertheless a crucial feature for any model to be used for inflation...... forecasting in a small open economy like Iceland....

  20. Radical prostatectomy: evolution of surgical technique from the laparoscopic point of view

    Directory of Open Access Journals (Sweden)

    Xavier Cathelineau

    2010-04-01

    Full Text Available PURPOSE: To review the literature and present a current picture of the evolution in radical prostatectomy from the laparoscopic point of view. MATERIALS AND METHODS: We conducted an extensive Medline literature search. Articles obtained regarding laparoscopic radical prostatectomy (LRP and our experience at Institut Montsouris were used for reassessing anatomical and technical issues in radical prostatectomy. RESULTS: LRP nuances were reassessed by surgical teams in order to verify possible weaknesses in their performance. Our basic approach was to carefully study the anatomy and pioneer open surgery descriptions in order to standardized and master a technique. The learning curve is presented in terms of an objective evaluation of outcomes for cancer control and functional results. In terms of technique-outcomes, there are several key elements in radical prostatectomy, such as dorsal vein control-apex exposure and nerve sparing with particular implications in oncological and functional results. Major variations among the surgical teams' performance and follow-up prevented objective comparisons in radical prostatectomy. The remarkable evolution of LRP needs to be supported by comprehensive results. CONCLUSIONS: Radical prostatectomy is a complex surgical operation with difficult objectives. Surgical technique should be standardized in order to allow an adequate and reliable performance in all settings, keeping in mind that cancer control remains the primary objective. Reassessing anatomy and a return to basics in surgical technique is the means to improve outcomes and overcome the difficult task of the learning curve, especially in minimally access urological surgery.

  1. ECM using Edwards curves

    DEFF Research Database (Denmark)

    Bernstein, Daniel J.; Birkner, Peter; Lange, Tanja

    2013-01-01

    -arithmetic level are as follows: (1) use Edwards curves instead of Montgomery curves; (2) use extended Edwards coordinates; (3) use signed-sliding-window addition-subtraction chains; (4) batch primes to increase the window size; (5) choose curves with small parameters and base points; (6) choose curves with large...

  2. Rational points on elliptic curves

    CERN Document Server

    Silverman, Joseph H

    2015-01-01

    The theory of elliptic curves involves a pleasing blend of algebra, geometry, analysis, and number theory. This book stresses this interplay as it develops the basic theory, thereby providing an opportunity for advanced undergraduates to appreciate the unity of modern mathematics. At the same time, every effort has been made to use only methods and results commonly included in the undergraduate curriculum. This accessibility, the informal writing style, and a wealth of exercises make Rational Points on Elliptic Curves an ideal introduction for students at all levels who are interested in learning about Diophantine equations and arithmetic geometry. Most concretely, an elliptic curve is the set of zeroes of a cubic polynomial in two variables. If the polynomial has rational coefficients, then one can ask for a description of those zeroes whose coordinates are either integers or rational numbers. It is this number theoretic question that is the main subject of this book. Topics covered include the geometry and ...

  3. Ahmed glaucoma valve implant: surgical technique and complications

    Directory of Open Access Journals (Sweden)

    Riva I

    2017-02-01

    Full Text Available Ivano Riva,1 Gloria Roberti,1 Francesco Oddone,1 Anastasios GP Konstas,2 Luciano Quaranta3 1IRCCS “Fondazione GB Bietti per l’Oftalmologia”, Rome, Italy; 21st University Department of Ophthalmology, Glaucoma Unit, AHEPA Hospital, Thessaloniki, Greece; 3Department of Medical and Surgical Specialties, Section of Ophthalmology, University of Brescia, Brescia, Italy Abstract: Implantation of Ahmed glaucoma valve is an effective surgical technique to reduce intraocular pressure in patients affected with glaucoma. While in the past, the use of this device was reserved to glaucoma refractory to multiple filtration surgical procedures, up-to-date mounting experience has encouraged its use also as a primary surgery for selected cases. Implantation of Ahmed glaucoma valve can be challenging for the surgeon, especially in patients who already underwent previous multiple surgeries. Several tips have to be acquired by the surgeon, and a long learning curve is always needed. Although the valve mechanism embedded in the Ahmed glaucoma valve decreases the risk of postoperative hypotony-related complications, it does not avoid the need of a careful follow-up. Complications related to this type of surgery include early and late postoperative hypotony, excessive capsule fibrosis around the plate, erosion of the tube or plate edge, and very rarely infection. The aim of this review is to describe surgical technique for Ahmed glaucoma valve implantation and to report related complications. Keywords: glaucoma, surgical technique, glaucoma drainage devices, Ahmed glaucoma valve, complications

  4. Longitudinal Examination of Procrastination and Anxiety, and Their Relation to Self-Efficacy for Self- Regulated Learning: Latent Growth Curve Modeling

    Science.gov (United States)

    Yerdelen, Sündüs; McCaffrey, Adam; Klassen, Robert M.

    2016-01-01

    This study investigated the longitudinal association between students' anxiety and procrastination and the relation of self-efficacy for self-regulation to these constructs. Latent Growth Curve Modeling was used to analyze data gathered from 182 undergraduate students (134 female, 48 male) at 4 times during a semester. Our results showed that…

  5. Future technological and economic performance of IGCC and FT production facilities with and without CO2 capture: Combining component based learning curve and bottom-up analysis

    NARCIS (Netherlands)

    Knoope, M.M.J.; Meerman, J.C.; Ramirez, C.A.; Faaij, A.P.C.

    2013-01-01

    This study aims to investigate the technological and economic prospects of integrated gasification facilities for power (IGCC) and Fischer–Tropsch (FT) liquid production with and without CCS over time. For this purpose, a component based experience curve was constructed and applied to identify the

  6. Surgical orthodontics.

    Science.gov (United States)

    Strohl, Alexis M; Vitkus, Lauren

    2017-08-01

    The article reviews some commonly used orthodontic treatments as well as new strategies to assist in the correction of malocclusion. Many techniques are used in conjunction with surgical intervention and are a necessary compliment to orthognathic surgery. Basic knowledge of these practices will aid in the surgeon's ability to adequately treat the patient. Many orthodontists and surgeons are eliminating presurgical orthodontics to adopt a strategy of 'surgery first' orthodontics in orthognathic surgery. This has the benefit of immediate improvement in facial aesthetics and shorter treatment times. The advent of virtual surgical planning has helped facilitate the development of this new paradigm by making surgical planning faster and easier. Furthermore, using intraoperative surgical navigation is improving overall precision and outcomes. A variety of surgical and nonsurgical treatments may be employed in the treatment of malocclusion. It is important to be familiar with all options available and tailor the patient's treatment plan accordingly. Surgery-first orthodontics, intraoperative surgical navigation, virtual surgical planning, and 3D printing are evolving new techniques that are producing shorter treatment times and subsequently improving patient satisfaction without sacrificing long-term stability.

  7. Contractibility of curves

    Directory of Open Access Journals (Sweden)

    Janusz Charatonik

    1991-11-01

    Full Text Available Results concerning contractibility of curves (equivalently: of dendroids are collected and discussed in the paper. Interrelations tetween various conditions which are either sufficient or necessary for a curve to be contractible are studied.

  8. The potential for machine learning algorithms to improve and reduce the cost of 3-dimensional printing for surgical planning.

    Science.gov (United States)

    Huff, Trevor J; Ludwig, Parker E; Zuniga, Jorge M

    2018-05-01

    3D-printed anatomical models play an important role in medical and research settings. The recent successes of 3D anatomical models in healthcare have led many institutions to adopt the technology. However, there remain several issues that must be addressed before it can become more wide-spread. Of importance are the problems of cost and time of manufacturing. Machine learning (ML) could be utilized to solve these issues by streamlining the 3D modeling process through rapid medical image segmentation and improved patient selection and image acquisition. The current challenges, potential solutions, and future directions for ML and 3D anatomical modeling in healthcare are discussed. Areas covered: This review covers research articles in the field of machine learning as related to 3D anatomical modeling. Topics discussed include automated image segmentation, cost reduction, and related time constraints. Expert commentary: ML-based segmentation of medical images could potentially improve the process of 3D anatomical modeling. However, until more research is done to validate these technologies in clinical practice, their impact on patient outcomes will remain unknown. We have the necessary computational tools to tackle the problems discussed. The difficulty now lies in our ability to collect sufficient data.

  9. Mentor Tutoring: An Efficient Method for Teaching Laparoscopic Colorectal Surgical Skills in a General Hospital.

    Science.gov (United States)

    Ichikawa, Nobuki; Homma, Shigenori; Yoshida, Tadashi; Ohno, Yosuke; Kawamura, Hideki; Wakizaka, Kazuki; Nakanishi, Kazuaki; Kazui, Keizo; Iijima, Hiroaki; Shomura, Hiroki; Funakoshi, Tohru; Nakano, Shiro; Taketomi, Akinobu

    2017-12-01

    We retrospectively assessed the efficacy of our mentor tutoring system for teaching laparoscopic colorectal surgical skills in a general hospital. A series of 55 laparoscopic colectomies performed by 1 trainee were evaluated. Next, the learning curves for high anterior resection performed by the trainee (n=20) were compared with those of a self-trained surgeon (n=19). Cumulative sum analysis and multivariate regression analyses showed that 38 completed cases were needed to reduce the operative time. In high anterior resection, the mean operative times were significantly shorter after the seventh average for the tutored surgeon compared with that for the self-trained surgeon. In cumulative sum charting, the curve reached a plateau by the seventh case for the tutored surgeon, but continued to increase for the self-trained surgeon. Mentor tutoring effectively teaches laparoscopic colorectal surgical skills in a general hospital setting.

  10. Surgical Instrument Sets for Special Operations Expeditionary Surgical Teams.

    Science.gov (United States)

    Hale, Diane F; Sexton, Justin C; Benavides, Linda C; Benavides, Jerry M; Lundy, Jonathan B

    The deployment of surgical assets has been driven by mission demands throughout years of military operations in Iraq and Afghanistan. The transition to the highly expeditious Golden Hour Offset Surgical Transport Team (GHOST- T) now offers highly mobile surgical assets in nontraditional operating rooms; the content of the surgical instrument sets has also transformed to accommodate this change. The 102nd Forward Surgical Team (FST) was attached to Special Operations assigned to southern Afghanistan from June 2015 to March 2016. The focus was to decrease overall size and weight of FST instrument sets without decreasing surgical capability of the GHOST-T. Each instrument set was evaluated and modified to include essential instruments to perform damage control surgery. The overall number of main instrument sets was decreased from eight to four; simplified augmentation sets have been added, which expand the capabilities of any main set. The overall size was decreased by 40% and overall weight decreased by 58%. The cardiothoracic, thoracotomy, and emergency thoracotomy trays were condensed to thoracic set. The orthopedic and amputation sets were replaced with an augmentation set of a prepackaged orthopedic external fixator set). An augmentation set to the major or minor basic sets, specifically for vascular injuries, was created. Through the reorganization of conventional FST surgical instrument sets to maintain damage control capabilities and mobility, the 102nd GHOST-T reduced surgical equipment volume and weight, providing a lesson learned for future surgical teams operating in austere environments. 2017.

  11. Surgical competence.

    Science.gov (United States)

    Patil, Nivritti G; Cheng, Stephen W K; Wong, John

    2003-08-01

    Recent high-profile cases have heightened the need for a formal structure to monitor achievement and maintenance of surgical competence. Logbooks, morbidity and mortality meetings, videos and direct observation of operations using a checklist, motion analysis devices, and virtual reality simulators are effective tools for teaching and evaluating surgical skills. As the operating theater is also a place for training, there must be protocols and guidelines, including mandatory standards for supervision, to ensure that patient care is not compromised. Patients appreciate frank communication and honesty from surgeons regarding their expertise and level of competence. To ensure that surgical competence is maintained and keeps pace with technologic advances, professional registration bodies have been promoting programs for recertification. They evaluate performance in practice, professional standing, and commitment to ongoing education.

  12. Are minimally invasive procedures harder to acquire than conventional surgical procedures?

    Science.gov (United States)

    Hiemstra, Ellen; Kolkman, Wendela; le Cessie, Saskia; Jansen, Frank Willem

    2011-01-01

    It is frequently suggested that minimally invasive surgery (MIS) is harder to acquire than conventional surgery. To test this hypothesis, residents' learning curves of both surgical skills are compared. Residents had to be assessed using a general global rating scale of the OSATS (Objective Structured Assessment of Technical Skills) for every procedure they performed as primary surgeon during a 3-month clinical rotation in gynecological surgery. Nine postgraduate-year-4 residents collected a total of 319 OSATS during the 2 years and 3 months investigation period. These assessments concerned 129 MIS (laparoscopic and hysteroscopic) and 190 conventional (open abdominal and vaginal) procedures. Learning curves (in this study defined as OSATS score plotted against procedure-specific caseload) for MIS and conventional surgery were compared using a linear mixed model. The MIS curve revealed to be steeper than the conventional curve (1.77 vs. 0.75 OSATS points per assessed procedure; 95% CI 1.19-2.35 vs. 0.15-1.35, p < 0.01). Basic MIS procedures do not seem harder to acquire during residency than conventional surgical procedures. This may have resulted from the incorporation of structured MIS training programs in residency. Hopefully, this will lead to a more successful implementation of the advanced MIS procedures. Copyright © 2010 S. Karger AG, Basel.

  13. Surgical specimen handover from the operating theatre to laboratory-Can we improve patient safety by learning from aviation and other high-risk organisations?

    Science.gov (United States)

    Brennan, Peter A; Brands, Marieke T; Caldwell, Lucy; Fonseca, Felipe Paiva; Turley, Nic; Foley, Susie; Rahimi, Siavash

    2018-02-01

    Essential communication between healthcare staff is considered one of the key requirements for both safety and quality care when patients are handed over from one clinical area to other. This is particularly important in environments such as the operating theatre and intensive care where mistakes can be devastating. Health care has learned from other high-risk organisations (HRO) such as aviation where the use of checklists and human factors awareness has virtually eliminated human error and mistakes. To our knowledge, little has been published around ways to improve pathology specimen handover following surgery, with pathology request forms often conveying the bare minimum of information to assist the laboratory staff. Furthermore, the request form might not warn staff about potential hazards. In this article, we provide a brief summary of the factors involved in human error and introduce a novel checklist that can be readily completed at the same time as the routine pathology request form. This additional measure enhances safety, can help to reduce processing and mislabelling errors and provides essential information in a structured way assisting both laboratory staff and pathologists when handling head and neck surgical specimens. © 2017 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  14. Integrating Patient-Reported Outcomes into Spine Surgical Care through Visual Dashboards: Lessons Learned from Human-Centered Design.

    Science.gov (United States)

    Hartzler, Andrea L; Chaudhuri, Shomir; Fey, Brett C; Flum, David R; Lavallee, Danielle

    2015-01-01

    The collection of patient-reported outcomes (PROs) draws attention to issues of importance to patients-physical function and quality of life. The integration of PRO data into clinical decisions and discussions with patients requires thoughtful design of user-friendly interfaces that consider user experience and present data in personalized ways to enhance patient care. Whereas most prior work on PROs focuses on capturing data from patients, little research details how to design effective user interfaces that facilitate use of this data in clinical practice. We share lessons learned from engaging health care professionals to inform design of visual dashboards, an emerging type of health information technology (HIT). We employed human-centered design (HCD) methods to create visual displays of PROs to support patient care and quality improvement. HCD aims to optimize the design of interactive systems through iterative input from representative users who are likely to use the system in the future. Through three major steps, we engaged health care professionals in targeted, iterative design activities to inform the development of a PRO Dashboard that visually displays patient-reported pain and disability outcomes following spine surgery. Design activities to engage health care administrators, providers, and staff guided our work from design concept to specifications for dashboard implementation. Stakeholder feedback from these health care professionals shaped user interface design features, including predefined overviews that illustrate at-a-glance trends and quarterly snapshots, granular data filters that enable users to dive into detailed PRO analytics, and user-defined views to share and reuse. Feedback also revealed important considerations for quality indicators and privacy-preserving sharing and use of PROs. Our work illustrates a range of engagement methods guided by human-centered principles and design recommendations for optimizing PRO Dashboards for patient

  15. Integrating Patient-Reported Outcomes into Spine Surgical Care through Visual Dashboards: Lessons Learned from Human-Centered Design

    Science.gov (United States)

    Hartzler, Andrea L.; Chaudhuri, Shomir; Fey, Brett C.; Flum, David R.; Lavallee, Danielle

    2015-01-01

    Introduction: The collection of patient-reported outcomes (PROs) draws attention to issues of importance to patients—physical function and quality of life. The integration of PRO data into clinical decisions and discussions with patients requires thoughtful design of user-friendly interfaces that consider user experience and present data in personalized ways to enhance patient care. Whereas most prior work on PROs focuses on capturing data from patients, little research details how to design effective user interfaces that facilitate use of this data in clinical practice. We share lessons learned from engaging health care professionals to inform design of visual dashboards, an emerging type of health information technology (HIT). Methods: We employed human-centered design (HCD) methods to create visual displays of PROs to support patient care and quality improvement. HCD aims to optimize the design of interactive systems through iterative input from representative users who are likely to use the system in the future. Through three major steps, we engaged health care professionals in targeted, iterative design activities to inform the development of a PRO Dashboard that visually displays patient-reported pain and disability outcomes following spine surgery. Findings: Design activities to engage health care administrators, providers, and staff guided our work from design concept to specifications for dashboard implementation. Stakeholder feedback from these health care professionals shaped user interface design features, including predefined overviews that illustrate at-a-glance trends and quarterly snapshots, granular data filters that enable users to dive into detailed PRO analytics, and user-defined views to share and reuse. Feedback also revealed important considerations for quality indicators and privacy-preserving sharing and use of PROs. Conclusion: Our work illustrates a range of engagement methods guided by human-centered principles and design

  16. Surgical Navigation

    DEFF Research Database (Denmark)

    Azarmehr, Iman; Stokbro, Kasper; Bell, R. Bryan

    2017-01-01

    Purpose: This systematic review investigates the most common indications, treatments, and outcomes of surgical navigation (SN) published from 2010 to 2015. The evolution of SN and its application in oral and maxillofacial surgery have rapidly developed over recent years, and therapeutic indicatio...

  17. Surgical Instrument

    NARCIS (Netherlands)

    Dankelman, J.; Horeman, T.

    2009-01-01

    The present invention relates to a surgical instrument for minimall-invasive surgery, comprising a handle, a shaft and an actuating part, characterised by a gastight cover surrounding the shaft, wherein the cover is provided with a coupler that has a feed- through opening with a loskable seal,

  18. JUMPING THE CURVE

    Directory of Open Access Journals (Sweden)

    René Pellissier

    2012-01-01

    Full Text Available This paper explores the notion ofjump ing the curve,following from Handy 's S-curve onto a new curve with new rules policies and procedures. . It claims that the curve does not generally lie in wait but has to be invented by leadership. The focus of this paper is the identification (mathematically and inferentially ofthat point in time, known as the cusp in catastrophe theory, when it is time to change - pro-actively, pre-actively or reactively. These three scenarios are addressed separately and discussed in terms ofthe relevance ofeach.

  19. [Simulation training in surgical education - application of virtual reality laparoscopic simulators in a surgical skills course].

    Science.gov (United States)

    Lehmann, K S; Gröne, J; Lauscher, J C; Ritz, J-P; Holmer, C; Pohlen, U; Buhr, H-J

    2012-04-01

    Training and simulation are gaining importance in surgical education. Today, virtual reality surgery simulators provide sophisticated laparoscopic training scenarios and offer detailed assessment methods. This also makes simulators interesting for the application in surgical skills courses. The aim of the current study was to assess the suitability of a virtual surgery simulator for training and assessment in an established surgical training course. The study was conducted during the annual "Practical Course for Visceral Surgery" (Warnemuende, Germany). 36 of 108 course participants were assigned at random for the study. Training was conducted in 15 sessions over 5 days with 4 identical virtual surgery simulators (LapSim) and 2 standardised training tasks. The simulator measured 16 individual parameters and calculated 2 scores. Questionnaires were used to assess the test persons' laparoscopic experience, their training situation and the acceptance of the simulator training. Data were analysed with non-parametric tests. A subgroup analysis for laparoscopic experience was conducted in order to assess the simulator's construct validity and assessment capabilities. Median age was 32 (27 - 41) years; median professional experience was 3 (1 - 11) years. Typical laparoscopic learning curves with initial significant improvements and a subsequent plateau phase were measured over 5 days. The individual training sessions exhibited a rhythmic variability in the training results. A shorter night's sleep led to a marked drop in performance. The participants' different experience levels could clearly be discriminated ( ≤ 20 vs. > 20 laparoscopic operations; p ≤ 0.001). The questionnaire showed that the majority of the participants had limited training opportunities in their hospitals. The simulator training was very well accepted. However, the participants severely misjudged the real costs of the simulators that were used. The learning curve on the

  20. Tornado-Shaped Curves

    Science.gov (United States)

    Martínez, Sol Sáez; de la Rosa, Félix Martínez; Rojas, Sergio

    2017-01-01

    In Advanced Calculus, our students wonder if it is possible to graphically represent a tornado by means of a three-dimensional curve. In this paper, we show it is possible by providing the parametric equations of such tornado-shaped curves.

  1. Simulating Supernova Light Curves

    International Nuclear Information System (INIS)

    Even, Wesley Paul; Dolence, Joshua C.

    2016-01-01

    This report discusses supernova light simulations. A brief review of supernovae, basics of supernova light curves, simulation tools used at LANL, and supernova results are included. Further, it happens that many of the same methods used to generate simulated supernova light curves can also be used to model the emission from fireballs generated by explosions in the earth's atmosphere.

  2. Simulating Supernova Light Curves

    Energy Technology Data Exchange (ETDEWEB)

    Even, Wesley Paul [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Dolence, Joshua C. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2016-05-05

    This report discusses supernova light simulations. A brief review of supernovae, basics of supernova light curves, simulation tools used at LANL, and supernova results are included. Further, it happens that many of the same methods used to generate simulated supernova light curves can also be used to model the emission from fireballs generated by explosions in the earth’s atmosphere.

  3. Image scaling curve generation

    NARCIS (Netherlands)

    2012-01-01

    The present invention relates to a method of generating an image scaling curve, where local saliency is detected in a received image. The detected local saliency is then accumulated in the first direction. A final scaling curve is derived from the detected local saliency and the image is then

  4. Image scaling curve generation.

    NARCIS (Netherlands)

    2011-01-01

    The present invention relates to a method of generating an image scaling curve, where local saliency is detected in a received image. The detected local saliency is then accumulated in the first direction. A final scaling curve is derived from the detected local saliency and the image is then

  5. Tempo curves considered harmful

    NARCIS (Netherlands)

    Desain, P.; Honing, H.

    1993-01-01

    In the literature of musicology, computer music research and the psychology of music, timing or tempo measurements are mostly presented in the form of continuous curves. The notion of these tempo curves is dangerous, despite its widespread use, because it lulls its users into the false impression

  6. The curve shortening problem

    CERN Document Server

    Chou, Kai-Seng

    2001-01-01

    Although research in curve shortening flow has been very active for nearly 20 years, the results of those efforts have remained scattered throughout the literature. For the first time, The Curve Shortening Problem collects and illuminates those results in a comprehensive, rigorous, and self-contained account of the fundamental results.The authors present a complete treatment of the Gage-Hamilton theorem, a clear, detailed exposition of Grayson''s convexity theorem, a systematic discussion of invariant solutions, applications to the existence of simple closed geodesics on a surface, and a new, almost convexity theorem for the generalized curve shortening problem.Many questions regarding curve shortening remain outstanding. With its careful exposition and complete guide to the literature, The Curve Shortening Problem provides not only an outstanding starting point for graduate students and new investigations, but a superb reference that presents intriguing new results for those already active in the field.

  7. Evolving Educational Techniques in Surgical Training.

    Science.gov (United States)

    Evans, Charity H; Schenarts, Kimberly D

    2016-02-01

    Training competent and professional surgeons efficiently and effectively requires innovation and modernization of educational methods. Today's medical learner is quite adept at using multiple platforms to gain information, providing surgical educators with numerous innovative avenues to promote learning. With the growth of technology, and the restriction of work hours in surgical education, there has been an increase in use of simulation, including virtual reality, robotics, telemedicine, and gaming. The use of simulation has shifted the learning of basic surgical skills to the laboratory, reserving limited time in the operating room for the acquisition of complex surgical skills". Copyright © 2016 Elsevier Inc. All rights reserved.

  8. SURGICAL EDUCATION

    African Journals Online (AJOL)

    based Learning (PBL) curriculum involved the simultaneous introduction of the .... of such teaching can likewise influence grade performance. A study conducted by .... supplemental instruction project: peer-devised and delivered tutorials.

  9. Robotic technology results in faster and more robust surgical skill acquisition than traditional laparoscopy.

    Science.gov (United States)

    Moore, Lee J; Wilson, Mark R; Waine, Elizabeth; Masters, Rich S W; McGrath, John S; Vine, Samuel J

    2015-03-01

    Technical surgical skills are said to be acquired quicker on a robotic rather than laparoscopic platform. However, research examining this proposition is scarce. Thus, this study aimed to compare the performance and learning curves of novices acquiring skills using a robotic or laparoscopic system, and to examine if any learning advantages were maintained over time and transferred to more difficult and stressful tasks. Forty novice participants were randomly assigned to either a robotic- or laparoscopic-trained group. Following one baseline trial on a ball pick-and-drop task, participants performed 50 learning trials. Participants then completed an immediate retention trial and a transfer trial on a two-instrument rope-threading task. One month later, participants performed a delayed retention trial and a stressful multi-tasking trial. The results revealed that the robotic-trained group completed the ball pick-and-drop task more quickly and accurately than the laparoscopic-trained group across baseline, immediate retention, and delayed retention trials. Furthermore, the robotic-trained group displayed a shorter learning curve for accuracy. The robotic-trained group also performed the more complex rope-threading and stressful multi-tasking transfer trials better. Finally, in the multi-tasking trial, the robotic-trained group made fewer tone counting errors. The results highlight the benefits of using robotic technology for the acquisition of technical surgical skills.

  10. The crime kuznets curve

    OpenAIRE

    Buonanno, Paolo; Fergusson, Leopoldo; Vargas, Juan Fernando

    2014-01-01

    We document the existence of a Crime Kuznets Curve in US states since the 1970s. As income levels have risen, crime has followed an inverted U-shaped pattern, first increasing and then dropping. The Crime Kuznets Curve is not explained by income inequality. In fact, we show that during the sample period inequality has risen monotonically with income, ruling out the traditional Kuznets Curve. Our finding is robust to adding a large set of controls that are used in the literature to explain the...

  11. Early experience using the da Vinci Surgical System for the treatment of mediastinal tumors.

    Science.gov (United States)

    Kajiwara, Naohiro; Taira, Masahiro; Yoshida, Koichi; Hagiwara, Masaru; Kakihana, Masatoshi; Usuda, Jitsuo; Uchida, Osamu; Ohira, Tatsuo; Kawate, Norihiko; Ikeda, Norihiko

    2011-10-01

    The da Vinci Surgical System has been used in only a few cases for treating mediastinal tumors in Japan. Recently, we used the da Vinci Surgical System for various types of anterior and middle mediastinal tumors in clinical practice. We report our early experience using the da Vinci Surgical System. Seven patients gave written informed consent to undergo robotic surgery for mediastinal tumor dissection using the da Vinci Surgical System. We evaluated the safety and feasibility of this system for the surgical treatment of mediastinal tumors. Two specialists in thoracic surgery who are certified to use the da Vinci S Surgical System and another specialist acted as an assistant performed the tumor dissection. We were able to access difficult-to-reach areas, such as the mediastinum, safely. All the resected tumors were classified as benign tumors histologically. The average da Vinci setting time was 14.0 min, the average working time was 55.7 min, and the average overall operating time was 125.9 min. The learning curve for the da Vinci setup and manipulation time was short. Robotic surgery enables mediastinal tumor dissection in certain cases more safely and easily than conventional video-assisted thoracoscopic surgery and less invasively than open thoracotomy.

  12. Bond yield curve construction

    Directory of Open Access Journals (Sweden)

    Kožul Nataša

    2014-01-01

    Full Text Available In the broadest sense, yield curve indicates the market's view of the evolution of interest rates over time. However, given that cost of borrowing it closely linked to creditworthiness (ability to repay, different yield curves will apply to different currencies, market sectors, or even individual issuers. As government borrowing is indicative of interest rate levels available to other market players in a particular country, and considering that bond issuance still remains the dominant form of sovereign debt, this paper describes yield curve construction using bonds. The relationship between zero-coupon yield, par yield and yield to maturity is given and their usage in determining curve discount factors is described. Their usage in deriving forward rates and pricing related derivative instruments is also discussed.

  13. SRHA calibration curve

    Data.gov (United States)

    U.S. Environmental Protection Agency — an UV calibration curve for SRHA quantitation. This dataset is associated with the following publication: Chang, X., and D. Bouchard. Surfactant-Wrapped Multiwalled...

  14. Bragg Curve Spectroscopy

    International Nuclear Information System (INIS)

    Gruhn, C.R.

    1981-05-01

    An alternative utilization is presented for the gaseous ionization chamber in the detection of energetic heavy ions, which is called Bragg Curve Spectroscopy (BCS). Conceptually, BCS involves using the maximum data available from the Bragg curve of the stopping heavy ion (HI) for purposes of identifying the particle and measuring its energy. A detector has been designed that measures the Bragg curve with high precision. From the Bragg curve the range from the length of the track, the total energy from the integral of the specific ionization over the track, the dE/dx from the specific ionization at the beginning of the track, and the Bragg peak from the maximum of the specific ionization of the HI are determined. This last signal measures the atomic number, Z, of the HI unambiguously

  15. ROBUST DECLINE CURVE ANALYSIS

    Directory of Open Access Journals (Sweden)

    Sutawanir Darwis

    2012-05-01

    Full Text Available Empirical decline curve analysis of oil production data gives reasonable answer in hyperbolic type curves situations; however the methodology has limitations in fitting real historical production data in present of unusual observations due to the effect of the treatment to the well in order to increase production capacity. The development ofrobust least squares offers new possibilities in better fitting production data using declinecurve analysis by down weighting the unusual observations. This paper proposes a robustleast squares fitting lmRobMM approach to estimate the decline rate of daily production data and compares the results with reservoir simulation results. For case study, we usethe oil production data at TBA Field West Java. The results demonstrated that theapproach is suitable for decline curve fitting and offers a new insight in decline curve analysis in the present of unusual observations.

  16. Power Curve Measurements FGW

    DEFF Research Database (Denmark)

    Georgieva Yankova, Ginka; Federici, Paolo

    This report describes power curve measurements carried out on a given turbine in a chosen period. The measurements are carried out in accordance to IEC 61400-12-1 Ed. 1 and FGW Teil 2.......This report describes power curve measurements carried out on a given turbine in a chosen period. The measurements are carried out in accordance to IEC 61400-12-1 Ed. 1 and FGW Teil 2....

  17. Curves and Abelian varieties

    CERN Document Server

    Alexeev, Valery; Clemens, C Herbert; Beauville, Arnaud

    2008-01-01

    This book is devoted to recent progress in the study of curves and abelian varieties. It discusses both classical aspects of this deep and beautiful subject as well as two important new developments, tropical geometry and the theory of log schemes. In addition to original research articles, this book contains three surveys devoted to singularities of theta divisors, of compactified Jacobians of singular curves, and of "strange duality" among moduli spaces of vector bundles on algebraic varieties.

  18. Deep-learnt classification of light curves

    DEFF Research Database (Denmark)

    Mahabal, Ashish; Gieseke, Fabian; Pai, Akshay Sadananda Uppinakudru

    2017-01-01

    is to derive statistical features from the time series and to use machine learning methods, generally supervised, to separate objects into a few of the standard classes. In this work, we transform the time series to two-dimensional light curve representations in order to classify them using modern deep......Astronomy light curves are sparse, gappy, and heteroscedastic. As a result standard time series methods regularly used for financial and similar datasets are of little help and astronomers are usually left to their own instruments and techniques to classify light curves. A common approach...... learning techniques. In particular, we show that convolutional neural networks based classifiers work well for broad characterization and classification. We use labeled datasets of periodic variables from CRTS survey and show how this opens doors for a quick classification of diverse classes with several...

  19. Surgical training in the Netherlands

    NARCIS (Netherlands)

    Borel-Rinkes, Inne H. M.; Gouma, Dirk J.; Hamming, Jaap F.

    2008-01-01

    Surgical training in the Netherlands has traditionally been characterized by learning on the job under the classic master-trainee doctrine. Over the past decades, it has become regionally organized with intensive structural training courses, and a peer-based quality control system. Recently, the

  20. Can skills assessment on a virtual reality trainer predict a surgical trainee's talent in laparoscopic surgery?

    Science.gov (United States)

    Rosenthal, R; Gantert, W A; Scheidegger, D; Oertli, D

    2006-08-01

    A number of studies have investigated several aspects of feasibility and validity of performance assessments with virtual reality surgical simulators. However, the validity of performance assessments is limited by the reliability of such measurements, and some issues of reliability still need to be addressed. This study aimed to evaluate the hypothesis that test subjects show logarithmic performance curves on repetitive trials for a component task of laparoscopic cholecystectomy on a virtual reality simulator, and that interindividual differences in performance after considerable training are significant. According to kinesiologic theory, logarithmic performance curves are expected and an individual's learning capacity for a specific task can be extrapolated, allowing quantification of a person's innate ability to develop task-specific skills. In this study, 20 medical students at the University of Basel Medical School performed five trials of a standardized task on the LS 500 virtual reality simulator for laparoscopic surgery. Task completion time, number of errors, economy of instrument movements, and maximum speed of instrument movements were measured. The hypothesis was confirmed by the fact that the performance curves for some of the simulator measurements were very close to logarithmic curves, and there were significant interindividual differences in performance at the end of the repetitive trials. Assessment of perceptual motor skills and the innate ability of an individual with no prior experience in laparoscopic surgery to develop such skills using the LS 500 VR surgical simulator is feasible and reliable.

  1. Approximation by planar elastic curves

    DEFF Research Database (Denmark)

    Brander, David; Gravesen, Jens; Nørbjerg, Toke Bjerge

    2016-01-01

    We give an algorithm for approximating a given plane curve segment by a planar elastic curve. The method depends on an analytic representation of the space of elastic curve segments, together with a geometric method for obtaining a good initial guess for the approximating curve. A gradient......-driven optimization is then used to find the approximating elastic curve....

  2. Using dummies for surgical skills training

    DEFF Research Database (Denmark)

    Langebæk, Rikke

    2011-01-01

    Effective acquisition of a skill requires practise. Therefore it is of great importance to provide veterinary students with opportunities to practice their surgical skills before carrying out surgical procedures on live patients. Some veterinary schools let students perform entire surgical...... procedures on research animals, in order to learn the basic skills along the way. From an ethical point of view it is questionable however to use live research animals for the sole purpose of practising surgery, and also, research animals are very costly. It is therefore necessary to identify alternative...... teaching methods for veterinary surgical training. At the Department of Small Animal Clinical Sciences, Faculty of Life Sciences, a number of low fidelity, stuffed toy animal dummies was developed for the Surgical Skills Lab in order to teach 4th year students the basic surgical skills. In the Surgical...

  3. Ahmed glaucoma valve implant: surgical technique and complications.

    Science.gov (United States)

    Riva, Ivano; Roberti, Gloria; Oddone, Francesco; Konstas, Anastasios Gp; Quaranta, Luciano

    2017-01-01

    Implantation of Ahmed glaucoma valve is an effective surgical technique to reduce intraocular pressure in patients affected with glaucoma. While in the past, the use of this device was reserved to glaucoma refractory to multiple filtration surgical procedures, up-to-date mounting experience has encouraged its use also as a primary surgery for selected cases. Implantation of Ahmed glaucoma valve can be challenging for the surgeon, especially in patients who already underwent previous multiple surgeries. Several tips have to be acquired by the surgeon, and a long learning curve is always needed. Although the valve mechanism embedded in the Ahmed glaucoma valve decreases the risk of postoperative hypotony-related complications, it does not avoid the need of a careful follow-up. Complications related to this type of surgery include early and late postoperative hypotony, excessive capsule fibrosis around the plate, erosion of the tube or plate edge, and very rarely infection. The aim of this review is to describe surgical technique for Ahmed glaucoma valve implantation and to report related complications.

  4. Power Curve Measurements REWS

    DEFF Research Database (Denmark)

    Gómez Arranz, Paula; Vesth, Allan

    This report describes the power curve measurements carried out on a given wind turbine in a chosen period. The measurements were carried out following the measurement procedure in the draft of IEC 61400-12-1 Ed.2 [1], with some deviations mostly regarding uncertainty calculation. Here, the refere......This report describes the power curve measurements carried out on a given wind turbine in a chosen period. The measurements were carried out following the measurement procedure in the draft of IEC 61400-12-1 Ed.2 [1], with some deviations mostly regarding uncertainty calculation. Here......, the reference wind speed used in the power curve is the equivalent wind speed obtained from lidar measurements at several heights between lower and upper blade tip, in combination with a hub height meteorological mast. The measurements have been performed using DTU’s measurement equipment, the analysis...

  5. Curved electromagnetic missiles

    International Nuclear Information System (INIS)

    Myers, J.M.; Shen, H.M.; Wu, T.T.

    1989-01-01

    Transient electromagnetic fields can exhibit interesting behavior in the limit of great distances from their sources. In situations of finite total radiated energy, the energy reaching a distant receiver can decrease with distance much more slowly than the usual r - 2 . Cases of such slow decrease have been referred to as electromagnetic missiles. All of the wide variety of known missiles propagate in essentially straight lines. A sketch is presented here of a missile that can follow a path that is strongly curved. An example of a curved electromagnetic missile is explicitly constructed and some of its properties are discussed. References to details available elsewhere are given

  6. Algebraic curves and cryptography

    CERN Document Server

    Murty, V Kumar

    2010-01-01

    It is by now a well-known paradigm that public-key cryptosystems can be built using finite Abelian groups and that algebraic geometry provides a supply of such groups through Abelian varieties over finite fields. Of special interest are the Abelian varieties that are Jacobians of algebraic curves. All of the articles in this volume are centered on the theme of point counting and explicit arithmetic on the Jacobians of curves over finite fields. The topics covered include Schoof's \\ell-adic point counting algorithm, the p-adic algorithms of Kedlaya and Denef-Vercauteren, explicit arithmetic on

  7. IGMtransmission: Transmission curve computation

    Science.gov (United States)

    Harrison, Christopher M.; Meiksin, Avery; Stock, David

    2015-04-01

    IGMtransmission is a Java graphical user interface that implements Monte Carlo simulations to compute the corrections to colors of high-redshift galaxies due to intergalactic attenuation based on current models of the Intergalactic Medium. The effects of absorption due to neutral hydrogen are considered, with particular attention to the stochastic effects of Lyman Limit Systems. Attenuation curves are produced, as well as colors for a wide range of filter responses and model galaxy spectra. Photometric filters are included for the Hubble Space Telescope, the Keck telescope, the Mt. Palomar 200-inch, the SUBARU telescope and UKIRT; alternative filter response curves and spectra may be readily uploaded.

  8. Surgical closure of persistent arterial duct with minimal invasive anterior thoracotomy: an alternative technique.

    Science.gov (United States)

    Fouilloux, Virginie; Gran, Célia; Kreitmann, Bernard

    2014-10-01

    Surgical approach for persistent ductus arteriosus ligation is typically a left lateral thoracotomy opening the pleural-space with left lung retraction. We describe an alternative approach, with a minimally invasive anterior parasternal incision. This is particularly adapted to preterm infants weighing less than 1.5 kg. This approach ensures a good exposure of vessels. We believe that it is safe, reliable and reproducible. The learning curve should not be an issue for surgeons used to manage low weight patients. Georg Thieme Verlag KG Stuttgart · New York.

  9. Surgical education and training in an outer metropolitan hospital: a qualitative study of surgical trainers and trainees.

    Science.gov (United States)

    Nestel, Debra; Harlim, Jennifer; Bryant, Melanie; Rampersad, Rajay; Hunter-Smith, David; Spychal, Bob

    2017-08-01

    The landscape of surgical training is changing. The anticipated increase in the numbers of surgical trainees and the shift to competency-based surgical training places pressures on an already stretched health service. With these pressures in mind, we explored trainers' and trainees' experiences of surgical training in a less traditional rotation, an outer metropolitan hospital. We considered practice-based learning theories to make meaning of surgical training in this setting, in particular Actor-network theory. We adopted a qualitative approach and purposively sampled surgical trainers and trainees to participate in individual interviews and focus groups respectively. Transcripts were made and thematically analysed. Institutional human research ethics approval was obtained. Four surgical trainers and fourteen trainees participated. Almost without exception, participants' report training needs to be well met. Emergent inter-related themes were: learning as social activity; learning and programmatic factors; learning and physical infrastructure; and, learning and organizational structure. This outer metropolitan hospital is suited to the provision of surgical training with the current rotational system for trainees. The setting offers experiences that enable consolidation of learning providing a rich and varied overall surgical training program. Although relational elements of learning were paramount they occurred within a complex environment. Actor-network theory was used to give meaning to emergent themes acknowledging that actors (both people and objects) and their interactions combine to influence training quality, shifting the focus of responsibility for learning away from individuals to the complex interactions in which they work and learn.

  10. Power Curve Measurements

    DEFF Research Database (Denmark)

    Federici, Paolo; Kock, Carsten Weber

    This report describes the power curve measurements performed with a nacelle LIDAR on a given wind turbine in a wind farm and during a chosen measurement period. The measurements and analysis are carried out in accordance to the guidelines in the procedure “DTU Wind Energy-E-0019” [1]. The reporting...

  11. Power Curve Measurements, FGW

    DEFF Research Database (Denmark)

    Vesth, Allan; Kock, Carsten Weber

    The report describes power curve measurements carried out on a given wind turbine. The measurements are carried out in accordance to Ref. [1]. A site calibration has been carried out; see Ref. [2], and the measured flow correction factors for different wind directions are used in the present...... analyze of power performance of the turbine....

  12. Power Curve Measurements

    DEFF Research Database (Denmark)

    Federici, Paolo; Vesth, Allan

    The report describes power curve measurements carried out on a given wind turbine. The measurements are carried out in accordance to Ref. [1]. A site calibration has been carried out; see Ref. [2], and the measured flow correction factors for different wind directions are used in the present...... analyze of power performance of the turbine....

  13. Power Curve Measurements

    DEFF Research Database (Denmark)

    Villanueva, Héctor; Gómez Arranz, Paula

    The report describes power curve measurements carried out on a given wind turbine. The measurements are carried out in accordance to Ref. [1]. A site calibration has been carried out; see Ref. [2], and the measured flow correction factors for different wind directions are used in the present...... analyze of power performance of the turbine...

  14. Carbon Lorenz Curves

    NARCIS (Netherlands)

    Groot, L.F.M.|info:eu-repo/dai/nl/073642398

    2008-01-01

    The purpose of this paper is twofold. First, it exhibits that standard tools in the measurement of income inequality, such as the Lorenz curve and the Gini-index, can successfully be applied to the issues of inequality measurement of carbon emissions and the equity of abatement policies across

  15. The Axial Curve Rotator.

    Science.gov (United States)

    Hunter, Walter M.

    This document contains detailed directions for constructing a device that mechanically produces the three-dimensional shape resulting from the rotation of any algebraic line or curve around either axis on the coordinate plant. The device was developed in response to student difficulty in visualizing, and thus grasping the mathematical principles…

  16. Nacelle lidar power curve

    DEFF Research Database (Denmark)

    Gómez Arranz, Paula; Wagner, Rozenn

    This report describes the power curve measurements performed with a nacelle LIDAR on a given wind turbine in a wind farm and during a chosen measurement period. The measurements and analysis are carried out in accordance to the guidelines in the procedure “DTU Wind Energy-E-0019” [1]. The reporting...

  17. Power curve report

    DEFF Research Database (Denmark)

    Vesth, Allan; Kock, Carsten Weber

    The report describes power curve measurements carried out on a given wind turbine. The measurements are carried out in accordance to Ref. [1]. A site calibration has been carried out; see Ref. [2], and the measured flow correction factors for different wind directions are used in the present...

  18. Textbook Factor Demand Curves.

    Science.gov (United States)

    Davis, Joe C.

    1994-01-01

    Maintains that teachers and textbook graphics follow the same basic pattern in illustrating changes in demand curves when product prices increase. Asserts that the use of computer graphics will enable teachers to be more precise in their graphic presentation of price elasticity. (CFR)

  19. ECM using Edwards curves

    NARCIS (Netherlands)

    Bernstein, D.J.; Birkner, P.; Lange, T.; Peters, C.P.

    2013-01-01

    This paper introduces EECM-MPFQ, a fast implementation of the elliptic-curve method of factoring integers. EECM-MPFQ uses fewer modular multiplications than the well-known GMP-ECM software, takes less time than GMP-ECM, and finds more primes than GMP-ECM. The main improvements above the

  20. Power Curve Measurements FGW

    DEFF Research Database (Denmark)

    Federici, Paolo; Kock, Carsten Weber

    The report describes power curve measurements carried out on a given wind turbine. The measurements are carried out in accordance to Ref. [1]. A site calibration has been carried out; see Ref. [2], and the measured flow correction factors for different wind directions are used in the present...... analyze of power performance of the turbine...

  1. The role of simulation in developing surgical skills.

    Science.gov (United States)

    Akhtar, K S N; Chen, Alvin; Standfield, N J; Gupte, C M

    2014-06-01

    Surgical training has followed the master-apprentice model for centuries but is currently undergoing a paradigm shift. The traditional model is inefficient with no guarantee of case mix, quality, or quantity. There is a growing focus on competency-based medical education in response to restrictions on doctors' working hours and the traditional mantra of "see one, do one, teach one" is being increasingly questioned. The medical profession is subject to more scrutiny than ever before and is facing mounting financial, clinical, and political pressures. Simulation may be a means of addressing these challenges. It provides a way for trainees to practice technical tasks in a protected environment without putting patients at risk and helps to shorten the learning curve. The evidence for simulation-based training in orthopedic surgery using synthetic models, cadavers, and virtual reality simulators is constantly developing, though further work is needed to ensure the transfer of skills to the operating theatre.

  2. Emotions in veterinary surgical students

    DEFF Research Database (Denmark)

    Langebæk, Rikke; Eika, Berit; Pedersen, Lene Tanggaard

    2012-01-01

    A surgical educational environment is potentially stressful and can negatively affect students' learning. The aim of the present study was to investigate the emotions experienced by veterinary students in relation to their first encounter with live-animal surgery and to identify possible sources...... of positive and negative emotions, respectively. During a Basic Surgical Skills course, 155 veterinary fourth-year students completed a survey. Of these, 26 students additionally participated in individual semi-structured interviews. The results of the study show that students often experienced a combination...

  3. Alcohol skin preparation causes surgical fires.

    Science.gov (United States)

    Rocos, B; Donaldson, L J

    2012-03-01

    Surgical fires are a rare but serious preventable safety risk in modern hospitals. Data from the US show that up to 650 surgical fires occur each year, with up to 5% causing death or serious harm. This study used the National Reporting and Learning Service (NRLS) database at the National Patient Safety Agency to explore whether spirit-based surgical skin preparation fluid contributes to the cause of surgical fires. The NRLS database was interrogated for all incidents of surgical fires reported between 1 March 2004 and 1 March 2011. Each report was scrutinised manually to discover the cause of the fire. Thirteen surgical fires were reported during the study period. Of these, 11 were found to be directly related to spirit-based surgical skin preparation or preparation soaked swabs and drapes. Despite manufacturer's instructions and warnings, surgical fires continue to occur. Guidance published in the UK and US states that spirit-based skin preparation solutions should continue to be used but sets out some precautions. It may be that fire risk should be included in pre-surgical World Health Organization checklists or in the surgical training curriculum. Surgical staff should be aware of the risk that spirit-based skin preparation fluids pose and should take action to minimise the chance of fire occurring.

  4. Codes and curves

    CERN Document Server

    Walker, Judy L

    2000-01-01

    When information is transmitted, errors are likely to occur. Coding theory examines efficient ways of packaging data so that these errors can be detected, or even corrected. The traditional tools of coding theory have come from combinatorics and group theory. Lately, however, coding theorists have added techniques from algebraic geometry to their toolboxes. In particular, by re-interpreting the Reed-Solomon codes, one can see how to define new codes based on divisors on algebraic curves. For instance, using modular curves over finite fields, Tsfasman, Vladut, and Zink showed that one can define a sequence of codes with asymptotically better parameters than any previously known codes. This monograph is based on a series of lectures the author gave as part of the IAS/PCMI program on arithmetic algebraic geometry. Here, the reader is introduced to the exciting field of algebraic geometric coding theory. Presenting the material in the same conversational tone of the lectures, the author covers linear codes, inclu...

  5. Carbon Lorenz Curves

    Energy Technology Data Exchange (ETDEWEB)

    Groot, L. [Utrecht University, Utrecht School of Economics, Janskerkhof 12, 3512 BL Utrecht (Netherlands)

    2008-11-15

    The purpose of this paper is twofold. First, it exhibits that standard tools in the measurement of income inequality, such as the Lorenz curve and the Gini-index, can successfully be applied to the issues of inequality measurement of carbon emissions and the equity of abatement policies across countries. These tools allow policy-makers and the general public to grasp at a single glance the impact of conventional distribution rules such as equal caps or grandfathering, or more sophisticated ones, on the distribution of greenhouse gas emissions. Second, using the Samuelson rule for the optimal provision of a public good, the Pareto-optimal distribution of carbon emissions is compared with the distribution that follows if countries follow Nash-Cournot abatement strategies. It is shown that the Pareto-optimal distribution under the Samuelson rule can be approximated by the equal cap division, represented by the diagonal in the Lorenz curve diagram.

  6. Dynamics of curved fronts

    CERN Document Server

    Pelce, Pierre

    1989-01-01

    In recent years, much progress has been made in the understanding of interface dynamics of various systems: hydrodynamics, crystal growth, chemical reactions, and combustion. Dynamics of Curved Fronts is an important contribution to this field and will be an indispensable reference work for researchers and graduate students in physics, applied mathematics, and chemical engineering. The book consist of a 100 page introduction by the editor and 33 seminal articles from various disciplines.

  7. International Wage Curves

    OpenAIRE

    David G. Blanchflower; Andrew J. Oswald

    1992-01-01

    The paper provides evidence for the existence of a negatively sloped locus linking the level of pay to the rate of regional (or industry) unemployment. This "wage curve" is estimated using microeconomic data for Britain, the US, Canada, Korea, Austria, Italy, Holland, Switzerland, Norway, and Germany, The average unemployment elasticity of pay is approximately -0.1. The paper sets out a multi-region efficiency wage model and argues that its predictions are consistent with the data.

  8. Anatomical curve identification

    Science.gov (United States)

    Bowman, Adrian W.; Katina, Stanislav; Smith, Joanna; Brown, Denise

    2015-01-01

    Methods for capturing images in three dimensions are now widely available, with stereo-photogrammetry and laser scanning being two common approaches. In anatomical studies, a number of landmarks are usually identified manually from each of these images and these form the basis of subsequent statistical analysis. However, landmarks express only a very small proportion of the information available from the images. Anatomically defined curves have the advantage of providing a much richer expression of shape. This is explored in the context of identifying the boundary of breasts from an image of the female torso and the boundary of the lips from a facial image. The curves of interest are characterised by ridges or valleys. Key issues in estimation are the ability to navigate across the anatomical surface in three-dimensions, the ability to recognise the relevant boundary and the need to assess the evidence for the presence of the surface feature of interest. The first issue is addressed by the use of principal curves, as an extension of principal components, the second by suitable assessment of curvature and the third by change-point detection. P-spline smoothing is used as an integral part of the methods but adaptations are made to the specific anatomical features of interest. After estimation of the boundary curves, the intermediate surfaces of the anatomical feature of interest can be characterised by surface interpolation. This allows shape variation to be explored using standard methods such as principal components. These tools are applied to a collection of images of women where one breast has been reconstructed after mastectomy and where interest lies in shape differences between the reconstructed and unreconstructed breasts. They are also applied to a collection of lip images where possible differences in shape between males and females are of interest. PMID:26041943

  9. Estimating Corporate Yield Curves

    OpenAIRE

    Antionio Diaz; Frank Skinner

    2001-01-01

    This paper represents the first study of retail deposit spreads of UK financial institutions using stochastic interest rate modelling and the market comparable approach. By replicating quoted fixed deposit rates using the Black Derman and Toy (1990) stochastic interest rate model, we find that the spread between fixed and variable rates of interest can be modeled (and priced) using an interest rate swap analogy. We also find that we can estimate an individual bank deposit yield curve as a spr...

  10. Costs for renewable electricity. Learning curves

    International Nuclear Information System (INIS)

    Harmsen, R.; Van Sambeek, E.J.W.

    2003-08-01

    The aim of the study on the title subject is to provide an objective basis for the determination of the assumptions that are used for the calculation of the so-called uneconomic top of electricity production from renewable energy sources, carried out by ECN and KEMA. The results will be used for the determination of the subsidy tariffs for new renewable energy projects and is part of the Environmental Quality of Electricity Production (MEP, abbreviated in Dutch) policy [nl

  11. Spain succeeds on the PWR learning curve

    International Nuclear Information System (INIS)

    Varley, J.

    1982-01-01

    The development of nuclear power in Spain is described. Although the programme has been delayed and cut back, success has been achieved in carrying out technology transfer. Spain now has an industry capable of exporting nuclear components, equipment and expertise. An architect-engineering capability has also developed. (U.K.)

  12. Automated Blazar Light Curves Using Machine Learning

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, Spencer James [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2017-07-27

    Every night in a remote clearing called Fenton Hill high in the Jemez Mountains of central New Mexico, a bank of robotically controlled telescopes tilt their lenses to the sky for another round of observation through digital imaging. Los Alamos National Laboratory’s Thinking Telescopes project is watching for celestial transients including high-power cosmic flashes called, and like all science, it can be messy work. To keep the project clicking along, Los Alamos scientists routinely install equipment upgrades, maintain the site, and refine the sophisticated machinelearning computer programs that process those images and extract useful data from them. Each week the system amasses 100,000 digital images of the heavens, some of which are compromised by clouds, wind gusts, focus problems, and so on. For a graduate student at the Lab taking a year’s break between master’s and Ph.D. studies, working with state-of-the-art autonomous telescopes that can make fundamental discoveries feels light years beyond the classroom.

  13. Mobile surgical skills education unit: a new concept in surgical training.

    Science.gov (United States)

    Shaikh, Faisal M; Hseino, Hazem; Hill, Arnold D K; Kavanagh, Eamon; Traynor, Oscar

    2011-08-01

    Basic surgical skills are an integral part of surgical training. Simulation-based surgical training offers an opportunity both to trainees and trainers to learn and teach surgical skills outside the operating room in a nonpatient, nonstressed environment. However, widespread adoption of simulation technology especially in medical education is prohibited by its inherent higher cost, limited space, and interruptions to clinical duties. Mobile skills laboratory has been proposed as a means to address some of these limitations. A new program is designed by the Royal College of Surgeons in Ireland (RCSI), in an approach to teach its postgraduate basic surgical trainees the necessary surgical skills, by making the use of mobile innovative simulation technology in their own hospital settings. In this article, authors describe the program and students response to the mobile surgical skills being delivered in the region of their training hospitals and by their own regional consultant trainers.

  14. PV experience curves for the Netherlands

    International Nuclear Information System (INIS)

    Gerwig, R.

    2005-01-01

    Experience curves are one of several tools used by policy makers to take a look at market development. Numerous curves have been constructed for PV but none specific to the Netherlands. The objective of this report is to take a look at the price development of grid-connected PV systems in the Netherlands using the experience curve theory. After a literature and internet search and attempts to acquire information from PV companies information on 51% of the totally installed capacity was found. Curves for the period 1991-2001 were constructed based on system price, BOS (balance-of-system) price and inverter price. The progress ratio of the locally learning BOS was similar to the globally learning module market. This indicates that the pace of development of the Dutch PV market is similar to the globally followed pace. Improvement of the detail of the data might help to get a better idea of which BOS components have declined most. The similar progress ratio also shows the importance of investing both in module and system research as is the case in the Netherlands

  15. Surgical Outcomes After Open, Laparoscopic, and Robotic Gastrectomy for Gastric Cancer.

    Science.gov (United States)

    Yang, Seung Yoon; Roh, Kun Ho; Kim, You-Na; Cho, Minah; Lim, Seung Hyun; Son, Taeil; Hyung, Woo Jin; Kim, Hyoung-Il

    2017-07-01

    In contrast to the significant advantages of laparoscopic versus open gastrectomy, robotic gastrectomy has shown little benefit over laparoscopic gastrectomy. This study aimed to compare multi-dimensional aspects of surgical outcomes after open, laparoscopic, and robotic gastrectomy. Data from 915 gastric cancer patients who underwent gastrectomy by one surgeon between March 2009 and May 2015 were retrospectively reviewed. Perioperative parameters were analyzed for short-term outcomes. Surgical success was defined as the absence of conversion to open surgery, major complications, readmission, positive resection margin, or fewer than 16 retrieved lymph nodes. This study investigated 241 patients undergoing open gastrectomy, 511 patients undergoing laparoscopic gastrectomy, and 173 patients undergoing robotic gastrectomy. For each approach, the respective incidences were as follows: conversion to open surgery (not applicable, 0.4%, and 0%; p = 0.444), in-hospital major complications (5.8, 2.7, and 1.2%; p = 0.020), delayed complications requiring readmission (2.9, 2.0, and 1.2%; p = 0.453), positive resection margin (1.7, 0, and 0%; p = 0.003), and inadequate number of retrieved lymph nodes (0.4, 4.1, and 1.7%; p = 0.010). Compared with open and laparoscopic surgery, robotic gastrectomy had the highest surgical success rate (90, 90.8, and 96.0%). Learning-curve analysis of success using cumulative sum plots showed success with the robotic approach from the start. Multivariate analyses identified age, sex, and gastrectomy extent as significant independent parameters affecting surgical success. Surgical approach was not a contributing factor. Open, laparoscopic, and robotic gastrectomy exhibited different incidences and causes of surgical failure. Robotic gastrectomy produced the best surgical outcomes, although the approach method itself was not an independent factor for success.

  16. Systematic Review of Patient-Specific Surgical Simulation: Toward Advancing Medical Education.

    Science.gov (United States)

    Ryu, Won Hyung A; Dharampal, Navjit; Mostafa, Ahmed E; Sharlin, Ehud; Kopp, Gail; Jacobs, William Bradley; Hurlbert, Robin John; Chan, Sonny; Sutherland, Garnette R

    Simulation-based education has been shown to be an effective tool to teach foundational technical skills in various surgical specialties. However, most of the current simulations are limited to generic scenarios and do not allow continuation of the learning curve beyond basic technical skills to prepare for more advanced expertise, such as patient-specific surgical planning. The objective of this study was to evaluate the current medical literature with respect to the utilization and educational value of patient-specific simulations for surgical training. We performed a systematic review of the literature using Pubmed, Embase, and Scopus focusing on themes of simulation, patient-specific, surgical procedure, and education. The study included randomized controlled trials, cohort studies, and case-control studies published between 2005 and 2016. Two independent reviewers (W.H.R. and N.D) conducted the study appraisal, data abstraction, and quality assessment of the studies. The search identified 13 studies that met the inclusion criteria; 7 studies employed computer simulations and 6 studies used 3-dimensional (3D) synthetic models. A number of surgical specialties evaluated patient-specific simulation, including neurosurgery, vascular surgery, orthopedic surgery, and interventional radiology. However, most studies were small in size and primarily aimed at feasibility assessments and early validation. Early evidence has shown feasibility and utility of patient-specific simulation for surgical education. With further development of this technology, simulation-based education may be able to support training of higher-level competencies outside the clinical settingto aid learners in their development of surgical skills. Copyright © 2017 Association of Program Directors in Surgery. Published by Elsevier Inc. All rights reserved.

  17. Experience Curves: A Tool for Energy Policy Assessment

    Energy Technology Data Exchange (ETDEWEB)

    Neij, Lena; Helby, Peter [Lund Univ. (Sweden). Environmental and Energy Systems Studies; Dannemand Andersen, Per; Morthorst, Poul Erik [Riso National Laboratory, Roskilde (Denmark); Durstewitz, Michael; Hoppe-Kilpper, Martin [Inst. fuer Solare Energieversorgungstechnik e.V., Kassel (DE); and others

    2003-07-01

    The objective of the project, Experience curves: a tool for energy policy assessment (EXTOOL), was to analyse the experience curve as a tool for the assessment of energy policy measures. This is of special interest, since the use of experience curves for the assessment of energy policy measures requires the development of the established experience curve methodology. This development raises several questions which have been addressed and analysed in this project. The analysis is based on case studies of wind power, an area with considerable experience in technology development, deployment and policy measures. Therefore, a case study based on wind power provides a good opportunity to study the usefulness of experience curves as a tool for the assessment of energy policy measures. However, the results are discussed in terms of using experience curves for the assessment of any energy technology. The project shows that experience curves can be used to assess the effect of combined policy measures in terms of cost reductions. Moreover, the result of the project show that experience curves could be used to analyse international 'learning systems', i.e. cost reductions brought about by the development of wind power and policy measures used in other countries. Nevertheless, the use of experience curves for the assessment of policy programmes has several limitations. First, the analysis and assessment of policy programmes cannot be achieved unless relevant experience curves based on good data can be developed. The authors are of the opinion that only studies that provide evidence of the validity, reliability and relevance of experience curves should be taken into account in policy making. Second, experience curves provide an aggregated picture of the situation and more detailed analysis of various sources of cost reduction, and cost reductions resulting from individual policy measures, requires additional data and analysis tools. Third, we do not recommend the use of

  18. Uniformization of elliptic curves

    OpenAIRE

    Ülkem, Özge; Ulkem, Ozge

    2015-01-01

    Every elliptic curve E defined over C is analytically isomorphic to C*=qZ for some q ∊ C*. Similarly, Tate has shown that if E is defined over a p-adic field K, then E is analytically isomorphic to K*=qZ for some q ∊ K . Further the isomorphism E(K) ≅ K*/qZ respects the action of the Galois group GK/K, where K is the algebraic closure of K. I will explain the construction of this isomorphism.

  19. Study on the Cost of Solar Photovoltaic Power Generation Using Double-factors Learning Curve Model%太阳能光伏发电成本的双因素学习曲线模型研究

    Institute of Scientific and Technical Information of China (English)

    曾鸣; 鹿伟; 段金辉; 李娜

    2012-01-01

    随着太阳能这一新能源的开发,在低碳经济时代,降低光伏发电成本以提高其可利用性显得尤为重要.在Wright基本学习曲线模型的基础上,建立太阳能光伏发电的双因素学习曲线模型,研究了太阳能光伏组件累积生产量和累积研发量对太阳能光伏发电成本的影响.采用2001年至2010年10a的数据,运用最小二乘法,检验参数的显著性,进而确定模型的可行性.并利用此双因素学习曲线模型对我国未来10a的太阳能光伏发电成本做了预测,得出在累积生产量和累积研发量发展情况不同的情形下,光伏发电成本的降低程度不同.表明应大力开发太阳能光伏发电产业,平衡累积生产量和累积研发量,使太阳能光伏发电的成本降低.同时对如何降低光伏发电成本提出了建议,为政策制定者提供一定的参考.%Along with the development of solar energy, it is particularly important to reduce the cost of solar photovoltaic power generation to improve its availability for low carbon economic. The double- factors learning curve model of solar photovoltaic power generation is built based on the Wright's basic learning curve model, and the influence of the accumulated production amount and the accumulated research and development amount of solar photovoltaic modules on the cost of solar photovoltaic power generation is studied. The ten- year data between 2001 and 2010 are used to test the significance of the parameters and to confirm the feasibility of the model by using of the least square method. In the end, the cost of solar photovoltaic power generation in future ten years is predicted, and the conclusion is that the cost of solar photovoltaic power generation reduces in different degree under different development situation. At the same time, proposals for reducing the cost are given, which provides certain reference for policy makers.

  20. The impact of secondary-task type on the sensitivity of reaction-time based measurement of cognitive load for novices learning surgical skills using simulation.

    Science.gov (United States)

    Rojas, David; Haji, Faizal; Shewaga, Rob; Kapralos, Bill; Dubrowski, Adam

    2014-01-01

    Interest in the measurement of cognitive load (CL) in simulation-based education has grown in recent years. In this paper we present two pilot experiments comparing the sensitivity of two reaction time based secondary task measures of CL. The results suggest that simple reaction time measures are sensitive enough to detect changes in CL experienced by novice learners in the initial stages of simulation-based surgical skills training.

  1. Roc curves for continuous data

    CERN Document Server

    Krzanowski, Wojtek J

    2009-01-01

    Since ROC curves have become ubiquitous in many application areas, the various advances have been scattered across disparate articles and texts. ROC Curves for Continuous Data is the first book solely devoted to the subject, bringing together all the relevant material to provide a clear understanding of how to analyze ROC curves.The fundamental theory of ROC curvesThe book first discusses the relationship between the ROC curve and numerous performance measures and then extends the theory into practice by describing how ROC curves are estimated. Further building on the theory, the authors prese

  2. Micro-surgical endodontics.

    Science.gov (United States)

    Eliyas, S; Vere, J; Ali, Z; Harris, I

    2014-02-01

    Non-surgical endodontic retreatment is the treatment of choice for endodontically treated teeth with recurrent or residual disease in the majority of cases. In some cases, surgical endodontic treatment is indicated. Successful micro-surgical endodontic treatment depends on the accuracy of diagnosis, appropriate case selection, the quality of the surgical skills, and the application of the most appropriate haemostatic agents and biomaterials. This article describes the armamentarium and technical procedures involved in performing micro-surgical endodontics to a high standard.

  3. Optimising surgical training: use of feedback to reduce errors during a simulated surgical procedure.

    LENUS (Irish Health Repository)

    Boyle, Emily

    2011-08-01

    To assess the effect of proximate or immediate feedback during an intensive training session. The authors hypothesised that provision of feedback during a training session would improve performance and learning curves.

  4. Curved Josephson junction

    International Nuclear Information System (INIS)

    Dobrowolski, Tomasz

    2012-01-01

    The constant curvature one and quasi-one dimensional Josephson junction is considered. On the base of Maxwell equations, the sine–Gordon equation that describes an influence of curvature on the kink motion was obtained. It is showed that the method of geometrical reduction of the sine–Gordon model from three to lower dimensional manifold leads to an identical form of the sine–Gordon equation. - Highlights: ► The research on dynamics of the phase in a curved Josephson junction is performed. ► The geometrical reduction is applied to the sine–Gordon model. ► The results of geometrical reduction and the fundamental research are compared.

  5. Curved-Duct

    Directory of Open Access Journals (Sweden)

    Je Hyun Baekt

    2000-01-01

    Full Text Available A numerical study is conducted on the fully-developed laminar flow of an incompressible viscous fluid in a square duct rotating about a perpendicular axis to the axial direction of the duct. At the straight duct, the rotation produces vortices due to the Coriolis force. Generally two vortex cells are formed and the axial velocity distribution is distorted by the effect of this Coriolis force. When a convective force is weak, two counter-rotating vortices are shown with a quasi-parabolic axial velocity profile for weak rotation rates. As the rotation rate increases, the axial velocity on the vertical centreline of the duct begins to flatten and the location of vorticity center is moved near to wall by the effect of the Coriolis force. When the convective inertia force is strong, a double-vortex secondary flow appears in the transverse planes of the duct for weak rotation rates but as the speed of rotation increases the secondary flow is shown to split into an asymmetric configuration of four counter-rotating vortices. If the rotation rates are increased further, the secondary flow restabilizes to a slightly asymmetric double-vortex configuration. Also, a numerical study is conducted on the laminar flow of an incompressible viscous fluid in a 90°-bend square duct that rotates about axis parallel to the axial direction of the inlet. At a 90°-bend square duct, the feature of flow by the effect of a Coriolis force and a centrifugal force, namely a secondary flow by the centrifugal force in the curved region and the Coriolis force in the downstream region, is shown since the centrifugal force in curved region and the Coriolis force in downstream region are dominant respectively.

  6. Elliptic curves for applications (Tutorial)

    NARCIS (Netherlands)

    Lange, T.; Bernstein, D.J.; Chatterjee, S.

    2011-01-01

    More than 25 years ago, elliptic curves over finite fields were suggested as a group in which the Discrete Logarithm Problem (DLP) can be hard. Since then many researchers have scrutinized the security of the DLP on elliptic curves with the result that for suitably chosen curves only exponential

  7. Titration Curves: Fact and Fiction.

    Science.gov (United States)

    Chamberlain, John

    1997-01-01

    Discusses ways in which datalogging equipment can enable titration curves to be measured accurately and how computing power can be used to predict the shape of curves. Highlights include sources of error, use of spreadsheets to generate titration curves, titration of a weak acid with a strong alkali, dibasic acids, weak acid and weak base, and…

  8. [Endoscopic calcaneoplasty (ECP) in Haglund's syndrome. Indication, surgical technique, surgical findings and results].

    Science.gov (United States)

    Jerosch, J; Sokkar, S; Dücker, M; Donner, A

    2012-06-01

    Posterior calcaneal exostosis treatment modalities have given rise to many controversial opinions. After failure of the conservative treatment, surgical bursectomy and resection of the calcaneal exostosis are indicated by many authors. But clinical studies also show a high rate of unsatisfactory results with a relative high incidence of complications. The minimally invasive surgical technique by an endoscopic calcaneoplasty (ECP) could be an option to overcome some of these problems. Between 1999 und 2010 we operated 164 patients with an age range between 16 and 67 years, 81 males and 83 females. The radiological examination prior to surgery documented in all cases a posterior superior calcaneal exostosis that showed friction to the Achilles tendon. All patients included in the study had no clinical varus of the hind foot, nor cavus deformities. All patients had undergone a trial of conservative treatment for at least 6 months and did not show a positive response. The average follow-up was 46.3 (range: 8-120) months. According to the Ogilvie-Harris score 71 patients presented good and 84 patients excellent results, while 5 patients showed fair results, and 4 patients only poor results. All the post-operative radiographs showed sufficient resection of the calcaneal spur. In 61 patients the preoperative MRI showed a partial rupture of the Achilles tendon close to the insertion side. In no case could we observe a complete tear at the time of follow-up. Only minor postoperative complications were observed. In many patients we could observe a chondral layer at the posterior aspect of the calcaneus. Close to the intersion the Achilles tendon showed also in many patients a chondroide metaplasia. ECP is an effective and minimally invasive procedure for the treatment of patients with calcaneal exostosis. After a short learning curve the endoscopic exposure is superior to the open technique, has less morbidity, less operating time, and nearly no complications. Moreover, the

  9. Surgical ergonomics. Analysis of technical skills, simulation models and assessment methods.

    Science.gov (United States)

    Papaspyros, Sotiris C; Kar, Ashok; O'Regan, David

    2015-06-01

    Over the past two centuries the surgical profession has undergone a profound evolution in terms of efficiency and outcomes. Societal concerns in relation to quality assurance, patient safety and cost reduction have highlighted the issue of training expert surgeons. The core elements of a training model build on the basic foundations of gross and fine motor skills. In this paper we provide an analysis of the ergonomic principles involved and propose relevant training techniques. We have endeavored to provide both the trainer and trainee perspectives. This paper is structured into four sections: 1) Pre-operative preparation issues, 2) technical skills and instrument handling, 3) low fidelity simulation models and 4) discussion of current concepts in crew resource management, deliberate practice and assessment. Rehearsal, warm-up and motivation-enhancing techniques aid concentration and focus. Appropriate posture, comprehension of ergonomic principles in relation to surgical instruments and utilisation of the non-dominant hand are essential skills to master. Low fidelity models can be used to achieve significant progress through the early stages of the learning curve. Deliberate practice and innate ability are complementary to each other and may be considered useful adjuncts to surgical skills development. Safe medical care requires that complex patient interventions be performed by highly skilled operators supported by reliable teams. Surgical ergonomics lie at the heart of any training model that aims to produce professionals able to function as leaders of a patient safety oriented culture. Copyright © 2015 IJS Publishing Group Limited. Published by Elsevier Ltd. All rights reserved.

  10. Risk factors of surgical failure following transvaginal mesh repair for the treatment of pelvic organ prolapse.

    Science.gov (United States)

    Long, Cheng-Yu; Lo, Tsia-Shu; Wang, Chiu-Lin; Wu, Chin-Hu; Liu, Cheng-Min; Su, Juin-Huang

    2012-04-01

    To identify the factors associated with pelvic organ prolapse (POP) recurrence after transvaginal mesh (TVM) repair. One hundred and thirteen women with symptomatic POP stage II to IV were scheduled for TVM procedures. All subjects underwent urinalyses and pelvic examination using the POP quantification (POP-Q) staging system before and after surgery. Seven (6.2%) of 113 women reported POP recurrence after a mean follow-up time of 30 months. We performed a univariate analysis of patients' characteristics to identify the predictors of surgical failure after TVM. There was no difference between two groups as to body mass index, POP stage, mesh type, and preoperative urinary symptoms and urodynamic parameters (P>0.05). However, we found that uterine prolapse (P=0.016) and surgical experience (P=0.043) were two significant predictors of surgical failure. Multivariate logistic regression showed similar results. Advanced uterine prolapse and lack of surgical experience were two significant predictors of failure following TVM. POP recurrence after mesh repair appears to be unlikely beyond the learning curve. Crown Copyright © 2012. Published by Elsevier Ireland Ltd. All rights reserved.

  11. A Journey Between Two Curves

    Directory of Open Access Journals (Sweden)

    Sergey A. Cherkis

    2007-03-01

    Full Text Available A typical solution of an integrable system is described in terms of a holomorphic curve and a line bundle over it. The curve provides the action variables while the time evolution is a linear flow on the curve's Jacobian. Even though the system of Nahm equations is closely related to the Hitchin system, the curves appearing in these two cases have very different nature. The former can be described in terms of some classical scattering problem while the latter provides a solution to some Seiberg-Witten gauge theory. This note identifies the setup in which one can formulate the question of relating the two curves.

  12. Twelve tips for assessing surgical performance and use of technical assessment scales

    DEFF Research Database (Denmark)

    Strandbygaard, Jeanett; Scheele, Fedde; Sørensen, Jette Led

    2017-01-01

    Using validated assessment scales for technical competence can help structure and standardize assessment and feedback for both the trainee and the supervisor and thereby avoid bias and drive learning. Correct assessment of operative skills can establish learning curves and allow adequate monitoring....... However, the assessment of surgical performance is not an easy task, since it includes many proxy parameters, which are hard to measure. Although numerous technical assessment scales exist, both within laparoscopic and open surgery, the validity evidence is often sparse, and this can raise doubts about...... reliability and educational outcome. Furthermore, the implementation of technical assessment scales varies due to several obstacles and doubts about accurate use. In this 12-tips article, we aim to give the readers a critical and useful appraisal of some of the common questions and misunderstandings regarding...

  13. Soil Water Retention Curve

    Science.gov (United States)

    Johnson, L. E.; Kim, J.; Cifelli, R.; Chandra, C. V.

    2016-12-01

    Potential water retention, S, is one of parameters commonly used in hydrologic modeling for soil moisture accounting. Physically, S indicates total amount of water which can be stored in soil and is expressed in units of depth. S can be represented as a change of soil moisture content and in this context is commonly used to estimate direct runoff, especially in the Soil Conservation Service (SCS) curve number (CN) method. Generally, the lumped and the distributed hydrologic models can easily use the SCS-CN method to estimate direct runoff. Changes in potential water retention have been used in previous SCS-CN studies; however, these studies have focused on long-term hydrologic simulations where S is allowed to vary at the daily time scale. While useful for hydrologic events that span multiple days, the resolution is too coarse for short-term applications such as flash flood events where S may not recover its full potential. In this study, a new method for estimating a time-variable potential water retention at hourly time-scales is presented. The methodology is applied for the Napa River basin, California. The streamflow gage at St Helena, located in the upper reaches of the basin, is used as the control gage site to evaluate the model performance as it is has minimal influences by reservoirs and diversions. Rainfall events from 2011 to 2012 are used for estimating the event-based SCS CN to transfer to S. As a result, we have derived the potential water retention curve and it is classified into three sections depending on the relative change in S. The first is a negative slope section arising from the difference in the rate of moving water through the soil column, the second is a zero change section representing the initial recovery the potential water retention, and the third is a positive change section representing the full recovery of the potential water retention. Also, we found that the soil water moving has traffic jam within 24 hours after finished first

  14. Fermions in curved spacetimes

    Energy Technology Data Exchange (ETDEWEB)

    Lippoldt, Stefan

    2016-01-21

    In this thesis we study a formulation of Dirac fermions in curved spacetime that respects general coordinate invariance as well as invariance under local spin base transformations. We emphasize the advantages of the spin base invariant formalism both from a conceptual as well as from a practical viewpoint. This suggests that local spin base invariance should be added to the list of (effective) properties of (quantum) gravity theories. We find support for this viewpoint by the explicit construction of a global realization of the Clifford algebra on a 2-sphere which is impossible in the spin-base non-invariant vielbein formalism. The natural variables for this formulation are spacetime-dependent Dirac matrices subject to the Clifford-algebra constraint. In particular, a coframe, i.e. vielbein field is not required. We disclose the hidden spin base invariance of the vielbein formalism. Explicit formulas for the spin connection as a function of the Dirac matrices are found. This connection consists of a canonical part that is completely fixed in terms of the Dirac matrices and a free part that can be interpreted as spin torsion. The common Lorentz symmetric gauge for the vielbein is constructed for the Dirac matrices, even for metrics which are not linearly connected. Under certain criteria, it constitutes the simplest possible gauge, demonstrating why this gauge is so useful. Using the spin base formulation for building a field theory of quantized gravity and matter fields, we show that it suffices to quantize the metric and the matter fields. This observation is of particular relevance for field theory approaches to quantum gravity, as it can serve for a purely metric-based quantization scheme for gravity even in the presence of fermions. Hence, in the second part of this thesis we critically examine the gauge, and the field-parametrization dependence of renormalization group flows in the vicinity of non-Gaussian fixed points in quantum gravity. While physical

  15. American Pediatric Surgical Association

    Science.gov (United States)

    American Pediatric Surgical Association Search for: Login Resources + For Members For Professionals For Training Program Directors For Media For ... Surgical Outcomes Surveys & Results Publications Continuing Education + ExPERT Pediatric Surgery NaT Annual Meeting CME MOC Requirements Residents / ...

  16. Abortion - surgical - aftercare

    Science.gov (United States)

    ... this page: //medlineplus.gov/ency/patientinstructions/000658.htm Abortion - surgical - aftercare To use the sharing features on ... please enable JavaScript. You have had a surgical abortion. This is a procedure that ends pregnancy by ...

  17. Urogynecologic Surgical Mesh Implants

    Science.gov (United States)

    ... procedures performed to treat pelvic floor disorders with surgical mesh: Transvaginal mesh to treat POP Transabdominal mesh to treat ... address safety risks Final Order for Reclassification of Surgical Mesh for Transvaginal Pelvic Organ Prolapse Repair Final Order for Effective ...

  18. Incorporating simulation into gynecologic surgical training.

    Science.gov (United States)

    Wohlrab, Kyle; Jelovsek, J Eric; Myers, Deborah

    2017-11-01

    Today's educational environment has made it more difficult to rely on the Halstedian model of "see one, do one, teach one" in gynecologic surgical training. There is decreased surgical volume, but an increased number of surgical modalities. Fortunately, surgical simulation has evolved to fill the educational void. Whether it is through skill generalization or skill transfer, surgical simulation has shifted learning from the operating room back to the classroom. This article explores the principles of surgical education and ways to introduce simulation as an adjunct to residency training. We review high- and low-fidelity surgical simulators, discuss the progression of surgical skills, and provide options for skills competency assessment. Time and money are major hurdles when designing a simulation curriculum, but low-fidelity models, intradepartmental cost sharing, and utilizing local experts for simulation proctoring can aid in developing a simulation program. Copyright © 2017 Elsevier Inc. All rights reserved.

  19. ANALYSIS OF THE SECONDARY CURVES IN PATIENTS UNDERGOING SELECTIVE ARTHRODESIS LENKE I

    Directory of Open Access Journals (Sweden)

    TADEU GERVAZONI DEBOM

    2015-12-01

    Full Text Available Objective : To radiographically evaluate the behavior of the secondary curves in the coronal and sagittal planes in patients with AIS classified as Lenke I, who underwent surgical treatment of selective arthrodesis by posterior approach. Methods : Retrospective study which analyzed 40 patients with AIS, being 33 female. The measurement of the radiographic parameters used followed the recommendations by Cobb. Results : The average correction of the thoracic proximal, primary and lumbar curves was 34.73%, 75.06% and 64.64%, respectively. Conclusion : Surgical treatment by selective arthrodesis in cases of AIS Lenke type I provide correction of compensatory curves in the coronal and maintenance in the sagittal plane.

  20. Models of genus one curves

    OpenAIRE

    Sadek, Mohammad

    2010-01-01

    In this thesis we give insight into the minimisation problem of genus one curves defined by equations other than Weierstrass equations. We are interested in genus one curves given as double covers of P1, plane cubics, or complete intersections of two quadrics in P3. By minimising such a curve we mean making the invariants associated to its defining equations as small as possible using a suitable change of coordinates. We study the non-uniqueness of minimisations of the genus one curves des...

  1. Virtual reality in surgical education.

    Science.gov (United States)

    Ota, D; Loftin, B; Saito, T; Lea, R; Keller, J

    1995-03-01

    Virtual reality (VR) is an emerging technology that can teach surgeons new procedures and can determine their level of competence before they operate on patients. Also VR allows the trainee to return to the same procedure or task several times later as a refresher course. Laparoscopic surgery is a new operative technique which requires the surgeon to observe the operation on a video-monitor and requires the acquisition of new skills. VR simulation could duplicate the operative field and thereby enhance training and reduce the need for expensive animal training models. Our preliminary experience has shown that we have the technology to model tissues and laparoscopic instruments and to develop in real time a VR learning environment for surgeons. Another basic need is to measure competence. Surgical training is an apprenticeship requiring close supervision and 5-7 years of training. Technical competence is judged by the mentor and has always been subjective. If VR surgical simulators are to play an important role in the future, quantitative measurement of competence would have to be part of the system. Because surgical competence is "vague" and is characterized by such terms as "too long, too short" or "too close, too far," it is possible that the principles of fuzzy logic could be used to measure competence in a VR surgical simulator. Because a surgical procedure consists of a series of tasks and each task is a series of steps, we will plan to create two important tasks in a VR simulator and validate their use. These tasks consist of laparoscopic knot tying and laparoscopic suturing. Our hypothesis is that VR in combination with fuzzy logic can educate surgeons and determine when they are competent to perform these procedures on patients.

  2. Digital curation and online resources: digital scanning of surgical tools at the royal college of physicians and surgeons of Glasgow for an open university learning resource.

    Science.gov (United States)

    Earley, Kirsty; Livingstone, Daniel; Rea, Paul M

    2017-01-01

    Collection preservation is essential for the cultural status of any city. However, presenting a collection publicly risks damage. Recently this drawback has been overcome by digital curation. Described here is a method of digitisation using photogrammetry and virtual reality software. Items were selected from the Royal College of Physicians and Surgeons of Glasgow archives, and implemented into an online learning module for the Open University. Images were processed via Agisoft Photoscan, Autodesk Memento, and Garden Gnome Object 2VR. Although problems arose due to specularity, 2VR digital models were developed for online viewing. Future research must minimise the difficulty of digitising specular objects.

  3. Anterior Overgrowth in Primary Curves, Compensatory Curves and Junctional Segments in Adolescent Idiopathic Scoliosis.

    Science.gov (United States)

    Schlösser, Tom P C; van Stralen, Marijn; Chu, Winnie C W; Lam, Tsz-Ping; Ng, Bobby K W; Vincken, Koen L; Cheng, Jack C Y; Castelein, René M

    2016-01-01

    Although much attention has been given to the global three-dimensional aspect of adolescent idiopathic scoliosis (AIS), the accurate three-dimensional morphology of the primary and compensatory curves, as well as the intervening junctional segments, in the scoliotic spine has not been described before. A unique series of 77 AIS patients with high-resolution CT scans of the spine, acquired for surgical planning purposes, were included and compared to 22 healthy controls. Non-idiopathic curves were excluded. Endplate segmentation and local longitudinal axis in endplate plane enabled semi-automatic geometric analysis of the complete three-dimensional morphology of the spine, taking inter-vertebral rotation, intra-vertebral torsion and coronal and sagittal tilt into account. Intraclass correlation coefficients for interobserver reliability were 0.98-1.00. Coronal deviation, axial rotation and the exact length discrepancies in the reconstructed sagittal plane, as defined per vertebra and disc, were analyzed for each primary and compensatory curve as well as for the junctional segments in-between. The anterior-posterior difference of spinal length, based on "true" anterior and posterior points on endplates, was +3.8% for thoracic and +9.4% for (thoraco)lumbar curves, while the junctional segments were almost straight. This differed significantly from control group thoracic kyphosis (-4.1%; P<0.001) and lumbar lordosis (+7.8%; P<0.001). For all primary as well as compensatory curves, we observed linear correlations between the coronal Cobb angle, axial rotation and the anterior-posterior length difference (r≥0.729 for thoracic curves; r≥0.485 for (thoraco)lumbar curves). Excess anterior length of the spine in AIS has been described as a generalized growth disturbance, causing relative anterior spinal overgrowth. This study is the first to demonstrate that this anterior overgrowth is not a generalized phenomenon. It is confined to the primary as well as the

  4. Quantum fields in curved space

    International Nuclear Information System (INIS)

    Birrell, N.D.; Davies, P.C.W.

    1982-01-01

    The book presents a comprehensive review of the subject of gravitational effects in quantum field theory. Quantum field theory in Minkowski space, quantum field theory in curved spacetime, flat spacetime examples, curved spacetime examples, stress-tensor renormalization, applications of renormalization techniques, quantum black holes and interacting fields are all discussed in detail. (U.K.)

  5. Extended analysis of cooling curves

    International Nuclear Information System (INIS)

    Djurdjevic, M.B.; Kierkus, W.T.; Liliac, R.E.; Sokolowski, J.H.

    2002-01-01

    Thermal Analysis (TA) is the measurement of changes in a physical property of a material that is heated through a phase transformation temperature range. The temperature changes in the material are recorded as a function of the heating or cooling time in such a manner that allows for the detection of phase transformations. In order to increase accuracy, characteristic points on the cooling curve have been identified using the first derivative curve plotted versus time. In this paper, an alternative approach to the analysis of the cooling curve has been proposed. The first derivative curve has been plotted versus temperature and all characteristic points have been identified with the same accuracy achieved using the traditional method. The new cooling curve analysis also enables the Dendrite Coherency Point (DCP) to be detected using only one thermocouple. (author)

  6. Social Media: Changing the Paradigm for Surgical Education.

    Science.gov (United States)

    Petrucci, Andrea M; Chand, Manish; Wexner, Steven D

    2017-09-01

    The role of social media (SoMe) in surgical education is emerging as a tool that augments and complements traditional learning. As SoMe usage has steadily increased in our personal and professional lives, it is no surprise that it has permeated into surgical education. Different SoMe sites offer distinct platforms from which knowledge can be transmitted, while catering to various learning styles. The purpose of this review is to outline the various SoMe platforms and their use in surgical education. Moreover, it will discuss their effectiveness in teaching and learning surgical knowledge and skills as well as other potential roles SoMe has to offer to improve surgical education.

  7. Enhancing surgical innovation through a specialized medical school pathway of excellence in innovation and entrepreneurship: Lessons learned and opportunities for the future.

    Science.gov (United States)

    Cohen, Mark S

    2017-11-01

    The mission of an academic medical center and academic departments of surgery focuses on teaching, scholarship/research, and expertise of clinical care. The standard 4-year medical school curriculum and general surgery residency training are well balanced to expose trainees to these missions in varying degrees, yet the advancement of medicine as a field is predicated on the creation, development, and successful implementation of medical innovations. Surgeons, by virtue of their clinical training, are immersed in medical technology and are continually required to use this technology effectively in combination with their own technical skills and judgment to provide optimal patient care. As such, they routinely face the challenges of current technology and the need for innovation and improvement, leading many to become natural inventors. Having a good idea or innovation to improve patient care, however, is just the starting point of the complex process of implementing that idea in the clinic. Unfortunately, the vast majority of surgeons and medical students have no formal educational training on the innovation process regarding how good ideas can be developed successfully for clinical and commercial implementation. Added to this lack of formal education are the limited resources and time constraints that surgeons, residents, and medical students face in acquiring the educational skill set to adeptly navigate this innovation and entrepreneurial landscape. To address these challenges, the University of Michigan recently created the first pathway of excellence for medical students to focus their passions and interests in medical innovation and entrepreneurship. This program has been transformative for building a new culture of young, motivated medical innovators, many of whom have dedicated their talents already to addressing several key problems in surgical patient care. Copyright © 2017 Elsevier Inc. All rights reserved.

  8. Duration of surgical-orthodontic treatment.

    Science.gov (United States)

    Häll, Birgitta; Jämsä, Tapio; Soukka, Tero; Peltomäki, Timo

    2008-10-01

    To study the duration of surgical-orthodontic treatment with special reference to patients' age and the type of tooth movements, i.e. extraction vs. non-extraction and intrusion before or extrusion after surgery to level the curve of Spee. The material consisted files of 37 consecutive surgical-orthodontic patients. The files were reviewed and gender, diagnosis, type of malocclusion, age at the initiation of treatment, duration of treatment, type of tooth movements (extraction vs. non-extraction and levelling of the curve of Spee before or after operation) and type of operation were retrieved. For statistical analyses two sample t-test, Kruskal-Wallis and Spearman rank correlation tests were used. Mean treatment duration of the sample was 26.8 months, of which pre-surgical orthodontics took on average 17.5 months. Patients with extractions as part of the treatment had statistically and clinically significantly longer treatment duration, on average 8 months, than those without extractions. No other studied variable seemed to have an impact on the treatment time. The present small sample size prevents reliable conclusions to be made. However, the findings suggest, and patients should be informed, that extractions included in the treatment plan increase chances of longer duration of surgical-orthodontic treatment.

  9. Liability exposure for surgical robotics instructors.

    Science.gov (United States)

    Lee, Yu L; Kilic, Gokhan; Phelps, John Y

    2012-01-01

    Surgical robotics instructors provide an essential service in improving the competency of novice gynecologic surgeons learning robotic surgery and advancing surgical skills on behalf of patients. However, despite best intentions, robotics instructors and the gynecologists who use their services expose themselves to liability. The fear of litigation in the event of a surgical complication may reduce the availability and utility of robotics instructors. A better understanding of the principles of duty of care and the physician-patient relationship, and their potential applicability in a court of law likely will help to dismantle some concerns and uncertainties about liability. This commentary is not meant to discourage current and future surgical instructors but to raise awareness of liability issues among robotics instructors and their students and to recommend certain preventive measures to curb potential liability risks. Published by Elsevier Inc.

  10. Improving core surgical training in a major trauma centre.

    Science.gov (United States)

    Morris, Daniel L J; Bryson, David J; Ollivere, Ben J; Forward, Daren P

    2016-06-01

    English Major Trauma Centres (MTCs) were established in April 2012. Increased case volume and complexity has influenced trauma and orthopaedic (T&O) core surgical training in these centres. To determine if T&O core surgical training in MTCs meets Joint Committee on Surgical Training (JCST) quality indicators including performance of T&O operative procedures and consultant supervised session attendance. An audit cycle assessing the impact of a weekly departmental core surgical trainee rota. The rota included allocated timetabled sessions that optimised clinical and surgical learning opportunities. Intercollegiate Surgical Curriculum Programme (ISCP) records for T&O core surgical trainees at a single MTC were analysed for 8 months pre and post rota introduction. Outcome measures were electronic surgical logbook evidence of leading T&O operative procedures and consultant validated work-based assessments (WBAs). Nine core surgical trainees completed a 4 month MTC placement pre and post introduction of the core surgical trainee rota. Introduction of core surgical trainee rota significantly increased the mean number of T&O operative procedures led by a core surgical trainee during a 4 month MTC placement from 20.2 to 34.0 (pcore surgical trainee during a 4 month MTC placement was significantly increased (0.3 vs 2.4 [p=0.04]). Those of dynamic hip screw fixation (2.3 vs 3.6) and ankle fracture fixation (0.7 vs 1.6) were not. Introduction of a core surgical trainee rota significantly increased the mean number of consultant validated WBAs completed by a core surgical trainee during a 4 month MTC placement from 1.7 to 6.6 (pcore surgical trainee rota utilising a 'problem-based' model can significantly improve T&O core surgical training in MTCs. Copyright © 2016 Elsevier Ltd. All rights reserved.

  11. Modeling Patterns of Activities using Activity Curves.

    Science.gov (United States)

    Dawadi, Prafulla N; Cook, Diane J; Schmitter-Edgecombe, Maureen

    2016-06-01

    Pervasive computing offers an unprecedented opportunity to unobtrusively monitor behavior and use the large amount of collected data to perform analysis of activity-based behavioral patterns. In this paper, we introduce the notion of an activity curve , which represents an abstraction of an individual's normal daily routine based on automatically-recognized activities. We propose methods to detect changes in behavioral routines by comparing activity curves and use these changes to analyze the possibility of changes in cognitive or physical health. We demonstrate our model and evaluate our change detection approach using a longitudinal smart home sensor dataset collected from 18 smart homes with older adult residents. Finally, we demonstrate how big data-based pervasive analytics such as activity curve-based change detection can be used to perform functional health assessment. Our evaluation indicates that correlations do exist between behavior and health changes and that these changes can be automatically detected using smart homes, machine learning, and big data-based pervasive analytics.

  12. [Surgical laboratory in pregraduate medicine.

    Science.gov (United States)

    Tapia-Jurado, Jesús

    2011-01-01

    Surgical laboratory in pregraduate students in medicine is beneficial and improves learning processes in cognitive aspects and skills acquisition. It is also an early initiation into scientific research. The laboratory is the introductory pathway into basic concepts of medical science (meaningful learning). It is also where students gain knowledge in procedures and abilities to obtain professional skills, an interactive teacher-student process. Medicine works rapidly to change from an art to a science. This fact compromises all schools and medical faculties to analyze their actual lesson plans. Simulators give students confidence and ability and save time, money and resources, eliminating at the same time the ethical factor of using live animals and the fear of patient safety. Multimedia programs may give a cognitive context evolving logically with an explanation based on written and visual animation followed by a clinical problem and its demonstration in a simulator, all before applying knowledge to the patient.

  13. Computational aspects of algebraic curves

    CERN Document Server

    Shaska, Tanush

    2005-01-01

    The development of new computational techniques and better computing power has made it possible to attack some classical problems of algebraic geometry. The main goal of this book is to highlight such computational techniques related to algebraic curves. The area of research in algebraic curves is receiving more interest not only from the mathematics community, but also from engineers and computer scientists, because of the importance of algebraic curves in applications including cryptography, coding theory, error-correcting codes, digital imaging, computer vision, and many more.This book cove

  14. Simulation-based surgical education.

    Science.gov (United States)

    Evgeniou, Evgenios; Loizou, Peter

    2013-09-01

    The reduction in time for training at the workplace has created a challenge for the traditional apprenticeship model of training. Simulation offers the opportunity for repeated practice in a safe and controlled environment, focusing on trainees and tailored to their needs. Recent technological advances have led to the development of various simulators, which have already been introduced in surgical training. The complexity and fidelity of the available simulators vary, therefore depending on our recourses we should select the appropriate simulator for the task or skill we want to teach. Educational theory informs us about the importance of context in professional learning. Simulation should therefore recreate the clinical environment and its complexity. Contemporary approaches to simulation have introduced novel ideas for teaching teamwork, communication skills and professionalism. In order for simulation-based training to be successful, simulators have to be validated appropriately and integrated in a training curriculum. Within a surgical curriculum, trainees should have protected time for simulation-based training, under appropriate supervision. Simulation-based surgical education should allow the appropriate practice of technical skills without ignoring the clinical context and must strike an adequate balance between the simulation environment and simulators. © 2012 The Authors. ANZ Journal of Surgery © 2012 Royal Australasian College of Surgeons.

  15. Leveraging electronic health records for predictive modeling of post-surgical complications.

    Science.gov (United States)

    Weller, Grant B; Lovely, Jenna; Larson, David W; Earnshaw, Berton A; Huebner, Marianne

    2017-01-01

    Hospital-specific electronic health record systems are used to inform clinical practice about best practices and quality improvements. Many surgical centers have developed deterministic clinical decision rules to discover adverse events (e.g. postoperative complications) using electronic health record data. However, these data provide opportunities to use probabilistic methods for early prediction of adverse health events, which may be more informative than deterministic algorithms. Electronic health record data from a set of 9598 colorectal surgery cases from 2010 to 2014 were used to predict the occurrence of selected complications including surgical site infection, ileus, and bleeding. Consistent with previous studies, we find a high rate of missing values for both covariates and complication information (4-90%). Several machine learning classification methods are trained on an 80% random sample of cases and tested on a remaining holdout set. Predictive performance varies by complication, although an area under the receiver operating characteristic curve as high as 0.86 on testing data was achieved for bleeding complications, and accuracy for all complications compares favorably to existing clinical decision rules. Our results confirm that electronic health records provide opportunities for improved risk prediction of surgical complications; however, consideration of data quality and consistency standards is an important step in predictive modeling with such data.

  16. 51Cr - erythrocyte survival curves

    International Nuclear Information System (INIS)

    Paiva Costa, J. de.

    1982-07-01

    Sixteen patients were studied, being fifteen patients in hemolytic state, and a normal individual as a witness. The aim was to obtain better techniques for the analysis of the erythrocytes, survival curves, according to the recommendations of the International Committee of Hematology. It was used the radiochromatic method as a tracer. Previously a revisional study of the International Literature was made in its aspects inherent to the work in execution, rendering possible to establish comparisons and clarify phonomena observed in cur investigation. Several parameters were considered in this study, hindering both the exponential and the linear curves. The analysis of the survival curves of the erythrocytes in the studied group, revealed that the elution factor did not present a homogeneous answer quantitatively to all, though, the result of the analysis of these curves have been established, through listed programs in the electronic calculator. (Author) [pt

  17. Melting curves of gammairradiated DNA

    International Nuclear Information System (INIS)

    Hofer, H.; Altmann, H.; Kehrer, M.

    1978-08-01

    Melting curves of gammairradiated DNA and data derived of them, are reported. The diminished stability is explained by basedestruction. DNA denatures completely at room temperature, if at least every fifth basepair is broken or weakened by irradiation. (author)

  18. Growth curves for Laron syndrome.

    OpenAIRE

    Laron, Z; Lilos, P; Klinger, B

    1993-01-01

    Growth curves for children with Laron syndrome were constructed on the basis of repeated measurements made throughout infancy, childhood, and puberty in 24 (10 boys, 14 girls) of the 41 patients with this syndrome investigated in our clinic. Growth retardation was already noted at birth, the birth length ranging from 42 to 46 cm in the 12/20 available measurements. The postnatal growth curves deviated sharply from the normal from infancy on. Both sexes showed no clear pubertal spurt. Girls co...

  19. Flow over riblet curved surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Loureiro, J B R; Freire, A P Silva, E-mail: atila@mecanica.ufrj.br [Mechanical Engineering Program, Federal University of Rio de Janeiro (COPPE/UFRJ), C.P. 68503, 21.941-972, Rio de Janeiro, RJ (Brazil)

    2011-12-22

    The present work studies the mechanics of turbulent drag reduction over curved surfaces by riblets. The effects of surface modification on flow separation over steep and smooth curved surfaces are investigated. Four types of two-dimensional surfaces are studied based on the morphometric parameters that describe the body of a blue whale. Local measurements of mean velocity and turbulence profiles are obtained through laser Doppler anemometry (LDA) and particle image velocimetry (PIV).

  20. Intersection numbers of spectral curves

    CERN Document Server

    Eynard, B.

    2011-01-01

    We compute the symplectic invariants of an arbitrary spectral curve with only 1 branchpoint in terms of integrals of characteristic classes in the moduli space of curves. Our formula associates to any spectral curve, a characteristic class, which is determined by the laplace transform of the spectral curve. This is a hint to the key role of Laplace transform in mirror symmetry. When the spectral curve is y=\\sqrt{x}, the formula gives Kontsevich--Witten intersection numbers, when the spectral curve is chosen to be the Lambert function \\exp{x}=y\\exp{-y}, the formula gives the ELSV formula for Hurwitz numbers, and when one chooses the mirror of C^3 with framing f, i.e. \\exp{-x}=\\exp{-yf}(1-\\exp{-y}), the formula gives the Marino-Vafa formula, i.e. the generating function of Gromov-Witten invariants of C^3. In some sense this formula generalizes ELSV, Marino-Vafa formula, and Mumford formula.

  1. Dissolution glow curve in LLD

    International Nuclear Information System (INIS)

    Haverkamp, U.; Wiezorek, C.; Poetter, R.

    1990-01-01

    Lyoluminescence dosimetry is based upon light emission during dissolution of previously irradiated dosimetric materials. The lyoluminescence signal is expressed in the dissolution glow curve. These curves begin, depending on the dissolution system, with a high peak followed by an exponentially decreasing intensity. System parameters that influence the graph of the dissolution glow curve, are, for example, injection speed, temperature and pH value of the solution and the design of the dissolution cell. The initial peak does not significantly correlate with the absorbed dose, it is mainly an effect of the injection. The decay of the curve consists of two exponential components: one fast and one slow. The components depend on the absorbed dose and the dosimetric materials used. In particular, the slow component correlates with the absorbed dose. In contrast to the fast component the argument of the exponential function of the slow component is independent of the dosimetric materials investigated: trehalose, glucose and mannitol. The maximum value, following the peak of the curve, and the integral light output are a measure of the absorbed dose. The reason for the different light outputs of various dosimetric materials after irradiation with the same dose is the differing solubility. The character of the dissolution glow curves is the same following irradiation with photons, electrons or neutrons. (author)

  2. Deriving DICOM surgical extensions from surgical workflows

    Science.gov (United States)

    Burgert, O.; Neumuth, T.; Gessat, M.; Jacobs, S.; Lemke, H. U.

    2007-03-01

    The generation, storage, transfer, and representation of image data in radiology are standardized by DICOM. To cover the needs of image guided surgery or computer assisted surgery in general one needs to handle patient information besides image data. A large number of objects must be defined in DICOM to address the needs of surgery. We propose an analysis process based on Surgical Workflows that helps to identify these objects together with use cases and requirements motivating for their specification. As the first result we confirmed the need for the specification of representation and transfer of geometric models. The analysis of Surgical Workflows has shown that geometric models are widely used to represent planned procedure steps, surgical tools, anatomical structures, or prosthesis in the context of surgical planning, image guided surgery, augmented reality, and simulation. By now, the models are stored and transferred in several file formats bare of contextual information. The standardization of data types including contextual information and specifications for handling of geometric models allows a broader usage of such models. This paper explains the specification process leading to Geometry Mesh Service Object Pair classes. This process can be a template for the definition of further DICOM classes.

  3. First report on joint use of a Da Vinci® surgical system with transfer of surgical know-how between two public hospitals.

    Science.gov (United States)

    Mattei, Agostino; Thoms, Michael; Ferrari, Matteo; La Croce, Giovanni; Danuser, Hansjörg; Schmid, Hans-Peter; Engeler, Daniel

    2014-01-01

    The costs of a Da Vinci® device for robot- assisted surgery, in particular for robot-assisted radical prostatectomy (RARP), can be a considerable issue for hospitals with limited caseloads. Since January 2011 the cantonal hospitals of Lucerne and St. Gallen (Switzerland) have shared a four-arm Da Vinci® device, transferring the surgical know-how by a Lucerne teaching surgeon to a St. Gallen surgeon. Complete pre- and perioperative data, including 3-month surgical RARP outcomes, were prospectively documented. For statistical analysis, Wilcoxon, exact Poisson and χ(2) tests were used. During the first year, the two hospitals (61 RARP patients in Lucerne, 19 RARP patients in St. Gallen) did not differ significantly in preoperative, perioperative or oncological and functional results except for prostate volume (median 33 [interquartile range 24-40] vs. 40 [interquartile range 33-57] ml; p = 0.02), operation time (mean 252 ± 49 vs. 351 ± 50 min; p = 0.0001), number of lymph nodes removed (median 16 [interquartile range 13-21] vs. 15 [interquartile range 8-16] nodes; p = 0.02), biopsy (p = 0.04) and specimen Gleason scores (p = 0.03), and length of hospital stay (median 8 [interquartile range 7-14] vs. 9 [interquartile range 8-18] days; p < 0.01). Da Vinci® device sharing with transfer of surgical know-how can reduce the costs of RARP without compromising surgical outcomes, even at the beginning of the learning curve. © 2014 S. Karger AG, Basel.

  4. Curve Boxplot: Generalization of Boxplot for Ensembles of Curves.

    Science.gov (United States)

    Mirzargar, Mahsa; Whitaker, Ross T; Kirby, Robert M

    2014-12-01

    In simulation science, computational scientists often study the behavior of their simulations by repeated solutions with variations in parameters and/or boundary values or initial conditions. Through such simulation ensembles, one can try to understand or quantify the variability or uncertainty in a solution as a function of the various inputs or model assumptions. In response to a growing interest in simulation ensembles, the visualization community has developed a suite of methods for allowing users to observe and understand the properties of these ensembles in an efficient and effective manner. An important aspect of visualizing simulations is the analysis of derived features, often represented as points, surfaces, or curves. In this paper, we present a novel, nonparametric method for summarizing ensembles of 2D and 3D curves. We propose an extension of a method from descriptive statistics, data depth, to curves. We also demonstrate a set of rendering and visualization strategies for showing rank statistics of an ensemble of curves, which is a generalization of traditional whisker plots or boxplots to multidimensional curves. Results are presented for applications in neuroimaging, hurricane forecasting and fluid dynamics.

  5. Recognizing surgical patterns

    NARCIS (Netherlands)

    Bouarfa, L.

    2012-01-01

    In the Netherlands, each year over 1700 patients die from preventable surgical errors. Numerous initiatives to improve surgical practice have had some impact, but problems persist. Despite the introduction of checklists and protocols, patient safety in surgery remains a continuing challenge. This is

  6. Surgical medical record

    DEFF Research Database (Denmark)

    Bulow, S.

    2008-01-01

    A medical record is presented on the basis of selected linguistic pearls collected over the years from surgical case records Udgivelsesdato: 2008/12/15......A medical record is presented on the basis of selected linguistic pearls collected over the years from surgical case records Udgivelsesdato: 2008/12/15...

  7. Spaghetti Sine Curves: Virtual Environments for Reasoning and Sense Making

    Science.gov (United States)

    Özgün-Koca, S. Asli; Edwards, Michael Todd; Meagher, Michael

    2013-01-01

    In a recent collaboration with an area high school teacher, the authors were asked to develop an introductory sinusoidal curves lesson for a group of second-year algebra students. Because the topic was abstract and unfamiliar to these tenth graders, they looked for hands-on lessons to support their learning. One lesson that they found, which they…

  8. Equilibrium spherically curved two-dimensional Lennard-Jones systems

    NARCIS (Netherlands)

    Voogd, J.M.; Sloot, P.M.A.; van Dantzig, R.

    2005-01-01

    To learn about basic aspects of nano-scale spherical molecular shells during their formation, spherically curved two-dimensional N-particle Lennard-Jones systems are simulated, studying curvature evolution paths at zero-temperature. For many N-values (N < 800) equilibrium configu- rations are traced

  9. Can a virtual reality surgical simulation training provide a self-driven and mentor-free skills learning? Investigation of the practical influence of the performance metrics from the virtual reality robotic surgery simulator on the skill learning and associated cognitive workloads.

    Science.gov (United States)

    Lee, Gyusung I; Lee, Mija R

    2018-01-01

    While it is often claimed that virtual reality (VR) training system can offer self-directed and mentor-free skill learning using the system's performance metrics (PM), no studies have yet provided evidence-based confirmation. This experimental study investigated what extent to which trainees achieved their self-learning with a current VR simulator and whether additional mentoring improved skill learning, skill transfer and cognitive workloads in robotic surgery simulation training. Thirty-two surgical trainees were randomly assigned to either the Control-Group (CG) or Experiment-Group (EG). While the CG participants reviewed the PM at their discretion, the EG participants had explanations about PM and instructions on how to improve scores. Each subject completed a 5-week training using four simulation tasks. Pre- and post-training data were collected using both a simulator and robot. Peri-training data were collected after each session. Skill learning, time spent on PM (TPM), and cognitive workloads were compared between groups. After the simulation training, CG showed substantially lower simulation task scores (82.9 ± 6.0) compared with EG (93.2 ± 4.8). Both groups demonstrated improved physical model tasks performance with the actual robot, but the EG had a greater improvement in two tasks. The EG exhibited lower global mental workload/distress, higher engagement, and a better understanding regarding using PM to improve performance. The EG's TPM was initially long but substantially shortened as the group became familiar with PM. Our study demonstrated that the current VR simulator offered limited self-skill learning and additional mentoring still played an important role in improving the robotic surgery simulation training.

  10. Considerations for reference pump curves

    International Nuclear Information System (INIS)

    Stockton, N.B.

    1992-01-01

    This paper examines problems associated with inservice testing (IST) of pumps to assess their hydraulic performance using reference pump curves to establish acceptance criteria. Safety-related pumps at nuclear power plants are tested under the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code (the Code), Section 11. The Code requires testing pumps at specific reference points of differential pressure or flow rate that can be readily duplicated during subsequent tests. There are many cases where test conditions cannot be duplicated. For some pumps, such as service water or component cooling pumps, the flow rate at any time depends on plant conditions and the arrangement of multiple independent and constantly changing loads. System conditions cannot be controlled to duplicate a specific reference value. In these cases, utilities frequently request to use pump curves for comparison of test data for acceptance. There is no prescribed method for developing a pump reference curve. The methods vary and may yield substantially different results. Some results are conservative when compared to the Code requirements; some are not. The errors associated with different curve testing techniques should be understood and controlled within reasonable bounds. Manufacturer's pump curves, in general, are not sufficiently accurate to use as reference pump curves for IST. Testing using reference curves generated with polynomial least squares fits over limited ranges of pump operation, cubic spline interpolation, or cubic spline least squares fits can provide a measure of pump hydraulic performance that is at least as accurate as the Code required method. Regardless of the test method, error can be reduced by using more accurate instruments, by correcting for systematic errors, by increasing the number of data points, and by taking repetitive measurements at each data point

  11. Learning

    Directory of Open Access Journals (Sweden)

    Mohsen Laabidi

    2014-01-01

    Full Text Available Nowadays learning technologies transformed educational systems with impressive progress of Information and Communication Technologies (ICT. Furthermore, when these technologies are available, affordable and accessible, they represent more than a transformation for people with disabilities. They represent real opportunities with access to an inclusive education and help to overcome the obstacles they met in classical educational systems. In this paper, we will cover basic concepts of e-accessibility, universal design and assistive technologies, with a special focus on accessible e-learning systems. Then, we will present recent research works conducted in our research Laboratory LaTICE toward the development of an accessible online learning environment for persons with disabilities from the design and specification step to the implementation. We will present, in particular, the accessible version “MoodleAcc+” of the well known e-learning platform Moodle as well as new elaborated generic models and a range of tools for authoring and evaluating accessible educational content.

  12. Curve Digitizer – A software for multiple curves digitizing

    Directory of Open Access Journals (Sweden)

    Florentin ŞPERLEA

    2010-06-01

    Full Text Available The Curve Digitizer is software that extracts data from an image file representing a graphicand returns them as pairs of numbers which can then be used for further analysis and applications.Numbers can be read on a computer screen stored in files or copied on paper. The final result is adata set that can be used with other tools such as MSEXCEL. Curve Digitizer provides a useful toolfor any researcher or engineer interested in quantifying the data displayed graphically. The image filecan be obtained by scanning a document

  13. [The transrectus sheath preperitoneal procedure: a safe, effective and cheap surgical approach to inguinal hernia?].

    Science.gov (United States)

    Prins, M W Wiesje; Voropai, D A Dasha; van Laarhoven, C J H M Kees; Akkersdijk, Willem L

    2013-01-01

    The main complication of surgery for inguinal hernia is chronic postoperative pain. This is often reported following the Lichtenstein procedure. A new, open surgical technique for the repair of inguinal hernia has been developed. This procedure is called the transrectus sheath preperitoneal procedure (TREPP). At TREPP a lightweight mesh with a ring made of memory metal is introduced into the preperitoneal space through the transrectus sheath. The first results of this operative technique are very promising: short operation time, short learning curve and not many patients with chronic postoperative pain. In a randomised, multi-centre study which will start mid-2013 (ISRCTN18591339), the TREPP procedure is compared with the transinguinal preperitoneal procedure. The primary outcome measure of this study is chronic postoperative pain.

  14. Playing off the curve - testing quantitative predictions of skill acquisition theories in development of chess performance.

    Science.gov (United States)

    Gaschler, Robert; Progscha, Johanna; Smallbone, Kieran; Ram, Nilam; Bilalić, Merim

    2014-01-01

    Learning curves have been proposed as an adequate description of learning processes, no matter whether the processes manifest within minutes or across years. Different mechanisms underlying skill acquisition can lead to differences in the shape of learning curves. In the current study, we analyze the tournament performance data of 1383 chess players who begin competing at young age and play tournaments for at least 10 years. We analyze the performance development with the goal to test the adequacy of learning curves, and the skill acquisition theories they are based on, for describing and predicting expertise acquisition. On the one hand, we show that the skill acquisition theories implying a negative exponential learning curve do a better job in both describing early performance gains and predicting later trajectories of chess performance than those theories implying a power function learning curve. On the other hand, the learning curves of a large proportion of players show systematic qualitative deviations from the predictions of either type of skill acquisition theory. While skill acquisition theories predict larger performance gains in early years and smaller gains in later years, a substantial number of players begin to show substantial improvements with a delay of several years (and no improvement in the first years), deviations not fully accounted for by quantity of practice. The current work adds to the debate on how learning processes on a small time scale combine to large-scale changes.

  15. Calibration curves for biological dosimetry

    International Nuclear Information System (INIS)

    Guerrero C, C.; Brena V, M. . E-mail cgc@nuclear.inin.mx

    2004-01-01

    The generated information by the investigations in different laboratories of the world, included the ININ, in which settles down that certain class of chromosomal leisure it increases in function of the dose and radiation type, has given by result the obtaining of calibrated curves that are applied in the well-known technique as biological dosimetry. In this work is presented a summary of the work made in the laboratory that includes the calibrated curves for gamma radiation of 60 Cobalt and X rays of 250 k Vp, examples of presumed exposure to ionizing radiation, resolved by means of aberration analysis and the corresponding dose estimate through the equations of the respective curves and finally a comparison among the dose calculations in those people affected by the accident of Ciudad Juarez, carried out by the group of Oak Ridge, USA and those obtained in this laboratory. (Author)

  16. Vertex algebras and algebraic curves

    CERN Document Server

    Frenkel, Edward

    2004-01-01

    Vertex algebras are algebraic objects that encapsulate the concept of operator product expansion from two-dimensional conformal field theory. Vertex algebras are fast becoming ubiquitous in many areas of modern mathematics, with applications to representation theory, algebraic geometry, the theory of finite groups, modular functions, topology, integrable systems, and combinatorics. This book is an introduction to the theory of vertex algebras with a particular emphasis on the relationship with the geometry of algebraic curves. The notion of a vertex algebra is introduced in a coordinate-independent way, so that vertex operators become well defined on arbitrary smooth algebraic curves, possibly equipped with additional data, such as a vector bundle. Vertex algebras then appear as the algebraic objects encoding the geometric structure of various moduli spaces associated with algebraic curves. Therefore they may be used to give a geometric interpretation of various questions of representation theory. The book co...

  17. Curve collection, extension of databases

    International Nuclear Information System (INIS)

    Gillemot, F.

    1992-01-01

    Full text: Databases: generally calculated data only. The original measurements: diagrams. Information loss between them Expensive research eg. irradiation, aging, creep etc. Original curves should be stored for reanalysing. The format of the stored curves: a. Data in ASCII files, only numbers b. Other information in strings in a second file Same name, but different extension. Extensions shows the type of the test and the type of the file. EXAMPLES. TEN is tensile information, TED is tensile data, CHN is Charpy informations, CHD is Charpy data. Storing techniques: digitalised measurements, digitalising old curves stored on paper. Use: making catalogues, reanalysing, comparison with new data. Tools: mathematical software packages like quattro, genplot, exel, mathcad, qbasic, pascal, fortran, mathlab, grapher etc. (author)

  18. Theoretical melting curve of caesium

    International Nuclear Information System (INIS)

    Simozar, S.; Girifalco, L.A.; Pennsylvania Univ., Philadelphia

    1983-01-01

    A statistical-mechanical model is developed to account for the complex melting curve of caesium. The model assumes the existence of three different species of caesium defined by three different electronic states. On the basis of this model, the free energy of melting and the melting curve are computed up to 60 kbar, using the solid-state data and the initial slope of the fusion curve as input parameters. The calculated phase diagram agrees with experiment to within the experimental error. Other thermodynamic properties including the entropy and volume of melting were also computed, and they agree with experiment. Since the theory requires only one adjustable constant, this is taken as strong evidence that the three-species model is satisfactory for caesium. (author)

  19. Migration and the Wage Curve:

    DEFF Research Database (Denmark)

    Brücker, Herbert; Jahn, Elke J.

    in a general equilibrium framework. For the empirical analysis we employ the IABS, a two percent sample of the German labor force. We find that the elasticity of the wage curve is particularly high for young workers and workers with a university degree, while it is low for older workers and workers......  Based on a wage curve approach we examine the labor market effects of migration in Germany. The wage curve relies on the assumption that wages respond to a change in the unemployment rate, albeit imperfectly. This allows one to derive the wage and employment effects of migration simultaneously...... with a vocational degree. The wage and employment effects of migration are moderate: a 1 percent increase in the German labor force through immigration increases the aggregate unemployment rate by less than 0.1 percentage points and reduces average wages by less 0.1 percent. While native workers benefit from...

  20. Laffer Curves and Home Production

    Directory of Open Access Journals (Sweden)

    Kotamäki Mauri

    2017-06-01

    Full Text Available In the earlier related literature, consumption tax rate Laffer curve is found to be strictly increasing (see Trabandt and Uhlig (2011. In this paper, a general equilibrium macro model is augmented by introducing a substitute for private consumption in the form of home production. The introduction of home production brings about an additional margin of adjustment – an increase in consumption tax rate not only decreases labor supply and reduces the consumption tax base but also allows a substitution of market goods with home-produced goods. The main objective of this paper is to show that, after the introduction of home production, the consumption tax Laffer curve exhibits an inverse U-shape. Also the income tax Laffer curves are significantly altered. The result shown in this paper casts doubt on some of the earlier results in the literature.

  1. Complexity of Curved Glass Structures

    Science.gov (United States)

    Kosić, T.; Svetel, I.; Cekić, Z.

    2017-11-01

    Despite the increasing number of research on the architectural structures of curvilinear forms and technological and practical improvement of the glass production observed over recent years, there is still a lack of comprehensive codes and standards, recommendations and experience data linked to real-life curved glass structures applications regarding design, manufacture, use, performance and economy. However, more and more complex buildings and structures with the large areas of glass envelope geometrically complex shape are built every year. The aim of the presented research is to collect data on the existing design philosophy on curved glass structure cases. The investigation includes a survey about how architects and engineers deal with different design aspects of curved glass structures with a special focus on the design and construction process, glass types and structural and fixing systems. The current paper gives a brief overview of the survey findings.

  2. Surgical ethics: surgical virtue and more.

    Science.gov (United States)

    Vercler, Christian J

    2015-01-01

    The encounter between a patient and her surgeon is unique for several reasons. The surgeon inflicts pain upon a patient for the patient's own good. An operative intervention is irreducibly personal, such that the decisions about and performance of operations are inseparable from the idiosyncrasies of the individual surgeon. Furthermore, there is a chasm of knowledge between the patient and surgeon that is difficult to cross. Hence, training in the discipline of surgery includes the inculcation of certain virtues and practices to safeguard against abuses of this relationship and to make sure that the best interests of the patient are prioritized. The stories in this issue are evidence that in contemporary practice this is not quite enough, as surgeons reflect on instances they felt were ethically challenging. Common themes include the difficulty in communicating surgical uncertainty, patient-surgeon relationships, ethical issues in surgical training, and the impact of the technological imperative on caring for dying patients.

  3. The Da Vinci Xi and robotic radical prostatectomy-an evolution in learning and technique.

    Science.gov (United States)

    Goonewardene, S S; Cahill, D

    2017-06-01

    The da Vinci Xi robot has been introduced as the successor to the Si platform. The promise of the Xi is to open the door to new surgical procedures. For robotic-assisted radical prostatectomy (RARP)/pelvic surgery, the potential is better vision and longer instruments. How has the Xi impacted on operative and pathological parameters as indicators of surgical performance? This is a comparison of an initial series of 42 RARPs with the Xi system in 2015 with a series using the Si system immediately before Xi uptake in the same calendar year, and an Si series by the same surgeon synchronously as the Xi series using operative time, blood loss, and positive margins as surrogates of surgical performance. Subjectively and objectively, there is a learning curve to Xi uptake in longer operative times but no impact on T2 positive margins which are the most reflective single measure of RARP outcomes. Subjectively, the vision of the Xi is inferior to the Si system, and the integrated diathermy system and automated setup are quirky. All require experience to overcome. There is a learning curve to progress from the Si to Xi da Vinci surgical platforms, but this does not negatively impact the outcome.

  4. Optimization on Spaces of Curves

    DEFF Research Database (Denmark)

    Møller-Andersen, Jakob

    in Rd, and methods to solve the initial and boundary value problem for geodesics allowing us to compute the Karcher mean and principal components analysis of data of curves. We apply the methods to study shape variation in synthetic data in the Kimia shape database, in HeLa cell nuclei and cycles...... of cardiac deformations. Finally we investigate a new application of Riemannian shape analysis in shape optimization. We setup a simple elliptic model problem, and describe how to apply shape calculus to obtain directional derivatives in the manifold of planar curves. We present an implementation based...

  5. Tracing a planar algebraic curve

    International Nuclear Information System (INIS)

    Chen Falai; Kozak, J.

    1994-09-01

    In this paper, an algorithm that determines a real algebraic curve is outlined. Its basic step is to divide the plane into subdomains that include only simple branches of the algebraic curve without singular points. Each of the branches is then stably and efficiently traced in the particular subdomain. Except for the tracing, the algorithm requires only a couple of simple operations on polynomials that can be carried out exactly if the coefficients are rational, and the determination of zeros of several polynomials of one variable. (author). 5 refs, 4 figs

  6. Signature Curves Statistics of DNA Supercoils

    OpenAIRE

    Shakiban, Cheri; Lloyd, Peter

    2004-01-01

    In this paper we describe the Euclidean signature curves for two dimensional closed curves in the plane and their generalization to closed space curves. The focus will be on discrete numerical methods for approximating such curves. Further we will apply these numerical methods to plot the signature curves related to three-dimensional simulated DNA supercoils. Our primary focus will be on statistical analysis of the data generated for the signature curves of the supercoils. We will try to esta...

  7. Surgical site infections

    African Journals Online (AJOL)

    Decrease the inflammatory response Vasodilatation leads to better perfusion and ... Must NOT be allowed to come in contact with brain, meninges, eyes or .... project (SCIP): Evolution of National Quality Measure. Surgical. Infection 2008 ...

  8. Surgical Critical Care Initiative

    Data.gov (United States)

    Federal Laboratory Consortium — The Surgical Critical Care Initiative (SC2i) is a USU research program established in October 2013 to develop, translate, and validate biology-driven critical care....

  9. Ambulatory Surgical Measures - Facility

    Data.gov (United States)

    U.S. Department of Health & Human Services — The Ambulatory Surgical Center Quality Reporting (ASCQR) Program seeks to make care safer and more efficient through quality reporting. ASCs eligible for this...

  10. Surgical Management of Hemorrhoids

    Science.gov (United States)

    Agbo, S. P.

    2011-01-01

    Hemorrhoids are common human afflictions known since the dawn of history. Surgical management of this condition has made tremendous progress from complex ligation and excision procedures in the past to simpler techniques that allow the patient to return to normal life within a short period. Newer techniques try to improve on the post-operative complications of older ones. The surgical options for the management of hemorrhoids today are many. Capturing all in a single article may be difficult if not impossible. The aim of this study therefore is to present in a concise form some of the common surgical options in current literature, highlighting some important post operative complications. Current literature is searched using MEDLINE, EMBASE and the Cochrane library. The conclusion is that even though there are many surgical options in the management of hemorrhoids today, most employ the ligature and excision technique with newer ones having reduced post operative pain and bleeding. PMID:22413048

  11. Surgical site infections

    African Journals Online (AJOL)

    Surgical site infections (SSIs) are a worldwide problem that has ... deep tissue is found on clinical examination, re-opening, histopathological or radiological investigation ..... Esposito S, Immune system and SSI, Journal of Chemotherapy, 2001.

  12. Surgical management of pain

    African Journals Online (AJOL)

    If these therapies fail, and with a thorough multidisciplinary approach involving carefully ... Generally, surgical pain management is divided into neuro- modulative .... 9 suggested. It is important to be sure that the underlying instability or.

  13. Dual Smarandache Curves of a Timelike Curve lying on Unit dual Lorentzian Sphere

    OpenAIRE

    Kahraman, Tanju; Hüseyin Ugurlu, Hasan

    2016-01-01

    In this paper, we give Darboux approximation for dual Smarandache curves of time like curve on unit dual Lorentzian sphere. Firstly, we define the four types of dual Smarandache curves of a timelike curve lying on dual Lorentzian sphere.

  14. Attempted establishment of proficiency levels for laparoscopic performance on a national scale using simulation: the results from the 2004 SAGES Minimally Invasive Surgical Trainer-Virtual Reality (MIST-VR) learning center study.

    Science.gov (United States)

    Van Sickle, K R; Ritter, E M; McClusky, D A; Lederman, A; Baghai, M; Gallagher, A G; Smith, C D

    2007-01-01

    The Minimally Invasive Surgical Trainer-Virtual Reality (MIST-VR) has been well validated as a training device for laparoscopic skills. It has been demonstrated that training to a level of proficiency on the simulator significantly improves operating room performance of laparoscopic cholecystectomy. The purpose of this project was to obtain a national standard of proficiency using the MIST-VR based on the performance of experienced laparoscopic surgeons. Surgeons attending the Society of American Gastrointestinal Endoscopic Surgeons (SAGES) 2004 Annual Scien