Learning curve Research Papers - Academia.edu (original) (raw)

The Earned Value Method (EVM) has been extensively applied for the analysis of construction projects. However, in cases where the productivity is not constant, but rather varies due to accelerations attributed to the learning phenomenon,... more

The Earned Value Method (EVM) has been extensively applied for the analysis of construction projects. However, in cases where the productivity is not constant, but rather varies due to accelerations attributed to the learning phenomenon, it is challenging to assess the implications on productivity estimation and forecasting. In that sense, such an investigation is crucial for the scheduling and coordination of the remaining works in a realistic manner. The purpose of this paper is to compare the progress reporting results using the Earned Value method both for the theoretical project time schedule (without learning) and the actual on-site scheduling following the learning curve. A real, large-scale infrastructure project is used as a case study. The research method involved the “transformation” of productivity data to cost data, with the purpose of quantifying the productivity improvements through the use of statistical learning models. The straight-line model was used, due to its w...

Learning curves in construction operations analysis is deemed as one of the main factors that determine the variation of on-site productivity and is always taken into account during the planning and estimation stage. This research... more

Learning curves in construction operations analysis is deemed as one of the main factors that determine the variation of on-site productivity and is always taken into account during the planning and estimation stage. This research attempts the assessment of learning curve models’ suitability for the effective analysis of the learning phenomenon for construction operations that are fairly complicated concerning a floating caisson fabrication process for a large-scale marine project, using productivity data. This paper investigates the role of published learning curve models (i.e. Straightline or Wright; Stanford “B”; Cubic; Piecewise or Stepwise; Exponential) by comparing their outcomes through the use of both unit and cumulative productivity data. There are two main research objectives: first, the model best fitting historical productivity data of construction activities that have been completed are investigated, while secondly, an attempt is made to determine which model better pre...

Background 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... more

Background 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 (T1) for all tasks (1 repetition of each task in consecutive order). In phase 2, participants underwent different training programs (30 consecutive repetitions) for basic ta...

Background Training of basic laparoscopic psychomotor skills improves both acquisition and retention of more advanced laparoscopic tasks, such as laparoscopic intra-corporeal knot tying (LICK). This randomized controlled trial (RCT) was... more

Background Training of basic laparoscopic psychomotor skills improves both acquisition and retention of more advanced laparoscopic tasks, such as laparoscopic intra-corporeal knot tying (LICK). This randomized controlled trial (RCT) was performed to evaluate the effect of different pre-training programs in hand-eye coordination (HEC) upon the learning curve of LICK. Results The study was performed in a private center in Asunción, Paraguay, by 60 residents/specialists in gynaecology with no experience in laparoscopic surgery. Participants were allocated in three groups. In phase 1, a baseline test was performed (T1, three repetitions). In phase 2, participants underwent different training programs for HEC (60 repetitions): G1 with both the dominant hand (DH) and the non-dominant hand (NDH), G2 with the DH only, G3 none. In phase 3, a post HEC/pre LICK training test was performed (T2, three repetitions). In phase 4, participants underwent a standardized training program for LICK (60 r...

Postoperative pain is a common symptom in the postoperative period in patients treated for incisional hernia, often refractory to treatment. The purpose of the this paper was to conduct a comparative study on the need for analgesic... more

Postoperative pain is a common symptom in the postoperative period in patients treated for incisional hernia, often refractory to treatment. The purpose of the this paper was to conduct a comparative study on the need for analgesic medication in patients operated for incisional hernia through a classical open approach and a laparoscopic approach. In this respect, we performed a retrospective observational study over a period of 4 years in which we introduced 92 patients operated for incisional hernia in the Surgery Clinic No. 1 of the Emergency County Hospital Tirgu Mures. For the reconstruction of the abdominal wall we used prosthetic materials (surgical meshes). All patients included in the study received only metamizole sodium as analgesic medication. The patients studied were divided into two groups: group A (consisting of 57 patients where open, classic surgical approach was used) and group B (consisting of 35 patients treated using a minimally invasive laparoscopic approach). ...

Background: Robotic-assisted radical prostatectomy (RARP) is being increasingly done in Canada. Despite this, the Canadian literature lacks publications on the oncologic and functional outcomes of RARP. The objective of this study is to... more

Background: Robotic-assisted radical prostatectomy (RARP) is being increasingly done in Canada. Despite this, the Canadian literature lacks publications on the oncologic and functional outcomes of RARP. The objective of this study is to report the longest single surgeon experience in the province of Quebec.Methods: We collected prospective data from 250 consecutive patients who underwent RARP by a single fellowship trained surgeon (AEH) from October 2006 to October 2012. Mean follow-up was 28 months (range: 1-72). The D’Amico risk stratification distribution was 34% in low-risk, 48% in intermediate-risk and 18% in high-risk groups.Results: The mean operation time (±SD) was 194 ± 60.6 minutes, and estimated blood loss 318 ± 179 mL. The transfusion rate was only 0.4%. All procedures were completed robotically. The mean hospital stay was 1.2 days, and 88% of patients were discharged on postoperative day 1. The mean catheterization time was 7 days (range: 6-13). There were 2% major (Cla...

The primary somatosensory cortex (S1) contains a map representation of the body surface. We hypothesized that S1 stimulation can successfully substitute for (or be substituted by) direct stimulation of skin receptors. We prepared rabbits... more

The primary somatosensory cortex (S1) contains a map representation of the body surface. We hypothesized that S1 stimulation can successfully substitute for (or be substituted by) direct stimulation of skin receptors. We prepared rabbits for evoking eyelid conditioned responses (CRs) using a trace “shock-air puff” paradigm. In a first series of experiments, animals received a conditioned stimulus (CS, a train of electrical pulses) in the whisker pad or in the S1 areas for vibrissae or for the hind limb. In the three cases, the CS was followed 250 ms from its end by an air puff presented to the cornea as an unconditioned stimulus (US). Learning curves from the three groups presented similar values, although animals stimulated with a central CS acquired their CRs faster. In a second series of experiments, animals were divided into four groups and were presented either centrally or peripherally with the same CS for six conditioning sessions. Then, the CS was switched from central to pe...

The conventional laparoscopic approach to rectal surgery has several limitations, and therefore many colorectal surgeons have great expectations for the robotic surgical system as an alternative modality in overcoming challenges of... more

The conventional laparoscopic approach to rectal surgery has several limitations, and therefore many colorectal surgeons have great expectations for the robotic surgical system as an alternative modality in overcoming challenges of laparoscopic surgery and thus enhancing oncologic and functional outcomes. The aim of this study was to evaluate the feasibility and short-term outcomes of robotic surgery for colorectal cancer as initial cases, compared with conventional laparoscopic surgery. From July 2015 to October 2015, fifteen patients with left-sided colon and rectal cancer underwent robotic surgery, and we compare with 20 patients received conventional laparoscopic surgery selected from our database of 153 patients with colorectal cancer operated in the last five years. Both groups were balanced in terms of age, gender, American Society of Anesthesiologists (ASA) score, body mass index (BMI), operative history, TNM staging, and tumor location using the propensity score matching me...

Background and Study Aims There is a paucity of literature on beginners' training and on its connection with patient safety for transforaminal epidural steroid injections (TFESIs). This study retrospectively assessed the learning... more

Background and Study Aims There is a paucity of literature on beginners' training and on its connection with patient safety for transforaminal epidural steroid injections (TFESIs). This study retrospectively assessed the learning curves and associated complications of neurosurgery residents never previously exposed to TFESI and compared them with experienced board-certified faculty neurosurgeons (BCFNs). Material and Methods Procedure time in minutes, dose-area product (DAP) in cGy*cm2, periprocedural observations, and complications in 354 TFESIs for radicular pain secondary to lumbar disk herniation or lumbar spinal stenosis were extracted from operative notes and the electronic infiltration logbook in the per-injection format. Learning curves for 238 residents and 116 BCFN TFESIs in terms of procedure time and DAP were estimated using monotone regression. Results Residents' TFESI procedure time and DAP reached BCFN level (4.7 minutes and 140.2 Gy*cm2) after 67 and 68 cases...

The concept of femoral neck preservation in total hip replacement (THR) was introduced in 1993. It is postulated that retaining cortical bone of the femoral neck offers triplanar stability, uniform stress distribution, and accommodates... more

The concept of femoral neck preservation in total hip replacement (THR) was introduced in 1993. It is postulated that retaining cortical bone of the femoral neck offers triplanar stability, uniform stress distribution, and accommodates physiological anteversion. However, data on safety, efficacy and learning curve are lacking. We prospectively assessed all patients who were operated for a THR with a short neck preserving stem (MiniHip) between 2012 and 2014. The safety and learning curve were assessed by recording operative time; stem size; and adverse events including periprosthetic fracture; paresthesia; and limb length discrepancy (LLD). The cohort was divided into equal groups to assess the learning curve effect, and the cumulative sums (CUSUM) test was performed to monitor intraoperative neck fractures. For assessment of efficacy, Oxford Hip Score (OHS) and Short Form-36 (SF-36) scores were compared preoperatively and postoperatively. 138 patients with median age 62 years (rang...

A nagyrugalmasságú szerkezetekben alkalmazható szilikon gumi típusok mechanikai, dinamikai, villamos, optikai tulajdonságainak rendszerező, és élettartam vizsgálatait végeztük el. Kimutattuk, hogy mely anyagtípusoknál helyettesíthetők a... more

A nagyrugalmasságú szerkezetekben alkalmazható szilikon gumi típusok mechanikai, dinamikai, villamos, optikai tulajdonságainak rendszerező, és élettartam vizsgálatait végeztük el. Kimutattuk, hogy mely anyagtípusoknál helyettesíthetők a nagy tisztaságú, drága orvosi szilikonok olcsóbb ipari típusokkal. Megmutattuk, hogy a prototípus gyártás területén szokásos két technológiával előállított szilikon gumi fontos mechanikai tulajdonságai között nincs meghatározó különbség. Az új, pneumatikus aktuátoros, digitális vezérlésű, testüreg-szonda ipari és orvosi alkalmazásra alkalmas. A gyógyászat területén nagy a mesterséges sphincter (bélelzáró) bionikai prototípusa, amely alapvetően eltér az ismert megoldástól. Az alakoptimalizálás fázisában van a minimál-invazív sebészethez nélkülözhetetlen védőcső és aktuátor. Igazoltuk a nagytisztaságú optikai szilikon kettőstörő tulajdonságát, és elsőként alkalmaztuk az effektust erőmérőben. A vezető szilikon gumi szenzor nagyrugalmasságú anyagokból ké...

PurposeThe purpose of this paper is to describe how, in the spring of 2007, Arizona State University Libraries held a focus group of selected faculty to discover their perceptions and use of electronic books (e‐books) in their research... more

PurposeThe purpose of this paper is to describe how, in the spring of 2007, Arizona State University Libraries held a focus group of selected faculty to discover their perceptions and use of electronic books (e‐books) in their research and teaching.Design/methodology/approachThe services of the Institute of Social Sciences Research were employed to recruit and moderate the focus group. Major themes explored were: use of e‐books as textbooks; use of e‐books for personal research; comparison between e‐books and print; disciplinary differences in perceptions of e‐books; and motivators for future use.FindingsOverall, the focus group revealed that faculty had generally unsatisfactory experiences in using e‐books in their research and teaching owing to the unreliability of access, lack of manipulability, and the steep learning curve of the various interfaces. However, most faculty agreed that e‐books would be a very viable and useful alternative if these issues were resolved.Research limi...

In this paper, which forms a chapter in the forthcoming Book “Delivering a Low Carbon Electricity System: Technologies, Economics and Policy” † , Jamasb and Kohler revisit the literature on learning curves and their application to energy... more

In this paper, which forms a chapter in the forthcoming Book “Delivering a Low Carbon Electricity System: Technologies, Economics and Policy” † , Jamasb and Kohler revisit the literature on learning curves and their application to energy technology and climate change policy analysis and modeling. The academic literature and policy documents have in recent years embraced the learning curves and applied the concept to technology analysis and forecasting cost reductions. We argue that learning curves have often been used or assumed uncritically in technology analysis and draw parallels between the use of learning rates in energy technological progress and climate change modeling to that of discount rates in social cost benefit analysis. The paper discusses that care needs to be taken in applying learning curves, originally developed as an empirical tool to assess the effect of learning by doing in manufacturing, to analysis innovation and technical change. Finally, we suggest some pote...

ObjectiveTo assess the learning curve for measurement of the fetal modified myocardial performance index (MPI).MethodsThree trainees with the theoretical knowledge of but without prior experience in performing MPI measurement were... more

ObjectiveTo assess the learning curve for measurement of the fetal modified myocardial performance index (MPI).MethodsThree trainees with the theoretical knowledge of but without prior experience in performing MPI measurement were selected. Each trainee and one experienced examiner measured MPI in a cohort of 90 consecutive fetuses. The average difference between the three trainees and the expert in the MPI measurements was calculated; a difference below 10% was considered to indicate an accurate measurement. Individual and averaged learning curves were delineated using cumulative sum analysis (CUSUM).ResultsThe gestational age at evaluation ranged from 20 + 4 to 41 + 4 (mean, 33 + 3) weeks. The CUSUM plots demonstrated that, on average, competence in performing fetal MPI measurement was achieved by 65 cases. The average number of attempts to achieve competence were 42, 77 and 83 for the ejection time, isovolumetric contraction time and isovolumetric relaxation time, respectively.Co...

Minimally invasive surgery (MIS) is being utilized more frequently as a surgical technique in general surgery and in paediatric urology. It is associated with a steep learning curve. Currently, the centre does not offer a MIS training... more

Minimally invasive surgery (MIS) is being utilized more frequently as a surgical technique in general surgery and in paediatric urology. It is associated with a steep learning curve. Currently, the centre does not offer a MIS training programme. It is hypothesized that the number of MIS procedures performed in the low-volume specialty of paediatric urology will offer insufficient training potential for surgeons. To assess the MIS training potential of a highly specialized, tertiary care, paediatric urology training centre that has been accredited by the Joint Committee of Paediatric Urology (JCPU). The clinical activity of the department was retrospectively reviewed by extracting the annual number of admissions, outpatient consultations and operative procedures. The operations were divided into open procedures and MIS. Major ablative procedures (nephrectomy) and reconstructive procedures (pyeloplasty) were analysed with reference to the patients' ages. The centre policy is not t...

The purpose of this thesis was to find out how the shape accuracy and surface roughness of an RF disk affect the machining time of a disk and the cost of the accelerating structures. The disks in question are part of a future Compact... more

The purpose of this thesis was to find out how the shape accuracy and surface roughness of an RF disk affect the machining time of a disk and the cost of the accelerating structures. The disks in question are part of a future Compact Linear Collider (CLIC) project. This thesis was made because the price of a single disk is