Initial Curve Research Articles

Magnetic training of the soft magnetorheological elastomers

The effect of repetitive quasi-static magnetisation of a magnetorheological elastomer on its magnetic response is discussed. Typical components of this material, namely soft silicone rubber and carbonyl iron powder, are used to produce magnetically sensitive composite samples. The composite specimens are examined by vibrating sample magnetometry. The influence of the elasticity of the composite matrix on the change in magnetic differential susceptibility of the material as a function of the number of repeated magnetisation cycles is evaluated. The soft matrix elastomers are characterised by the presence of maxima in the initial part of the differential susceptibility curves. The sample magnetisation values corresponding to such maxima vary with the number of magnetisation cycles. In addition, the initial magnetic susceptibility curves of soft samples obtained at different polarity of the applied field are not symmetrical. Symmetry is obtained by performing several subsequent magnetisation cycles. The differential susceptibility curves are affected by both reversible and irreversible processes related to particle mobility in the matrix. The magnetic response of composite samples with rigid matrices is more similar to that of classical soft magnetic materials.

Abstract 13371: Left Bundle Branch Area Pacing: Experiences From the First Two Years Implanting in an Academic Training Program

Background: Left bundle branch area pacing (LBBAP) has emerged as a more durable physiologic pacing strategy to His bundle pacing and a promising alternative to cardiac resynchronization therapy. Integration of this procedural technique within an academic training program has not yet been described. Objective: Highlight the procedural learning curve of implanting LBBAP leads within a fellowship program. Methods: Retrospective analysis of consecutive patients who underwent placement of a Medtronic 3830 lead for LBBAP at our institution from 1/2021-12/2022. Results: A total of 180 patients underwent LBBAP lead placement over the study time period. Overall, total procedure time was 133.7±58.2min, lead placement time 30.7±20.0min, fluoroscopy time 22.5±21.2 min, left bundle branch (LBB) capture rate 70% and paced QRS duration 128.6±19.3 ms. When dividing the study period by 6-month intervals, there was a rise in procedural volume (21, 28, 62 and 59 cases, respectively), a trend towards less fluoroscopy use (20.2±12.2, 16.7±9.1, 16.2±12.6 and 16.6±14.4 min), less total radiation (345.2±323.3, 317.2±630.9, 214.9±271.2 and 171.7±253.9 mGy), decreased LBBAP lead placement time (37.8±24.3, 30.7±16.3, 28.2±21.5, 30.6±18.7 min), decreased delivery system exchanges (19%, 11%, 8% and 2%*, *p≤0.01 from first six months) and improved LBB capture rates (50%, 69%, 83%*, 64%, *p≤0.01 from first six months). Both fellowship classes showed significant improvements in LBB capture rates (40% to 94% and 38% to 84%, p≤0.01 for both) and paced-QRS duration (140.0±27.2ms to 120.2±16.5ms and 136.2±21.8ms to 121.7±17.2ms, p≤0.05 for both) after 12 months of experience. Conclusion: Over the first two years of performing LBBAP in an academic training program, there was a rise in procedural volume with trends towards less fluoroscopy use, decreased LBBAP lead placement time with significantly decreased delivery system exchanges and improved LBB capture rates. Significant improvements in LBB capture rates and paced-QRS duration were seen by fellows after 12 months of experience. LBBAP is an increasingly popular pacing technique that can be effectively integrated within a training program, with early introduction important to accommodate the initial learning curve.

Initial Learning Curve for Robot-Assisted Total Knee Arthroplasty in a Dedicated Orthopedics Center.

Background and objectives: Our study aimed to assess the learning curve for robot-assisted (RA) total knee arthroplasty (TKA) in our hospital, compare operative times between RA-TKAs and manual TKAs, and assess the early complications rate between the two approaches. Methods: We included 39 patients who underwent RA-TKA and 45 control patients subjected to manual TKA in the same period and operated on by the same surgical staff. We collected demographic and patient-related data to assess potential differences between the two groups. Results: No statistical differences were recorded in regard to age, BMI, sex, Kellgren-Lawrence classification, or limb alignment between patients undergoing RA-TKA and manual TKA, respectively. Three surgeons transitioned from the learning to the proficiency phase in our study after a number of 6, 4, and 3 cases, respectively. The overall operative time for the learning phase was 111.54 ± 20.45 min, significantly longer compared to the average of 86.43 ± 19.09 min in the proficiency phase (p = 0.0154) and 80.56 ± 17.03 min for manual TKAs (p < 0.0001). No statistically significant difference was recorded between the global operative time for the proficiency phase TKAs versus the controls. No major complications were recorded in either RA-TKA or manual TKA groups. Conclusions: Our results suggest that experienced surgeons may adopt RA-TKA using this platform and quickly adapt without significant complications.

Analytical Inverse Preisach Model and Its Comparison With Inverse Jiles–Atherton Model in Terms of Accuracy and Computational Speed

Inverse hysteresis model with magnetic flux density and magnetic field intensity as input and output respectively is more preferred, compared with the forward one, for resolving the electromagnetic issues of electrical equipment in terms of magnetic vector potential or with voltage sources. And an inverse hysteresis model with high accuracy and high computation speed both has broader range of applications. However, the well known classical Preisach hysteresis model is formulated with the forward form, and has the double integration of its distribution function, making it inconvenient and unpractical in the electrical engineering. In this paper, an analytical inverse Preisach model is proposed for the first time. Firstly, the analytical expressions of permeability of initial magnetization curve, descending and ascending branches of the hysteresis loop are derived using one closed form of Everett integral function. Subsequently the analytical inverse Preisach model is derived by the difference method, considering the reversible magnetization component that classical Preisach model cannot simulate with an odd function analytically. The experiment of one grain oriented silicon steel sample and one non-oriented silicon steel sample, under different magnetic excitation levels is conducted, and the accuracy and efficiency of the proposed analytical inverse Preisach model are confirmed by comparing its simulated hysteresis loops with the experimental ones and that computed with the widely used inverse Jiles-Atherton hysteresis model.

FPGA-based pulsed laser with high modulation depth from Mach-Zehnder electro-optic modulator and its application

Mach-Zehnder electro-optic modulator as the essential component of high-speed modulation in the optical fiber communication and sensing system, its stability control of operating bias-point plays a key role in determining the transmission signal quality. Based on the output characteristic principle of Mach-Zehnder electro-optic modulator, researches on its bias-point drifting for causing the reduction mechanism of modulation depth and extinction ratio are analyzed. Switching its internal state machine from FPGA is proposed to automatically adjust the bias voltage in real time realizing the operating bias-point control of Mach-Zehnder electro-optic modulator, which is studied through the theoretical investigation. A pulsed laser with the temperature sensing system of fiber Bragg grating ring-down cavity based on FPGA is established experimentally to demonstrate its effectiveness. The experimental results show the modulation depth and the extinction ratio of pulsed laser are improved by 40.45% and 32.85 dB, respectively. Output characteristic curve of the sensing system is optimized, which includes the phenomenon of initial curve rise of ring-down signals and the distortion of ring-down waveform are eliminated. The good linearity, repeatability, stability and accuracy of sensing system are investigated at the continuous variation temperature from −30℃ to 30℃.

Socioeconomic, Racial, and Insurance Disparities in Clinical Outcomes After Surgery Among Patients With Idiopathic Scoliosis.

Socioeconomic status (SES), race, and insurance type correlate with initial curve severity for patients with idiopathic scoliosis, but less is known regarding how these variables impact surgical outcomes. The objectives of this study were to determine the influence of SES, race, and insurance on preoperative appointment attendance, likelihood of obtaining a preoperative second opinion, brace prescription, missed 6 or 12-month postsurgical appointments, incidence of emergency department visits 0 to 90 days after surgery, and major complications within a year of surgery. A review of 421 patients diagnosed with idiopathic scoliosis who underwent surgery at a single high-volume pediatric spinal deformity institution between May 2015 and October 2021 was conducted. Area Deprivation Index, a quantitative measure of SES, was collected. Scores were stratified by quartile; higher scores indicated a lower SES. χ 2 tests for correlation were performed to determine whether clinical outcomes were dependent upon Area Deprivation Index, race, or insurance type; P ≤0.05 was significant. The sample was 313 Caucasian (74%), 69 (16%) black, and 39 (9.3%) other patients. More patients had private versus public insurance (80% vs 20%) and were of higher SES. The likelihood of missing preoperative appointments was higher for black patients ( P = 0.037). Those with lower SES missed more postoperative appointments and received less bracing and second opinions ( P = 0.038, P = 0.017, P = 0.008, respectively). Being black and publicly insured correlated with fewer brace prescriptions ( P < 0.001, P = 0.050) and decreased rates of obtaining second opinions ( P = 0.004, P = 0.001). Patients with idiopathic scoliosis surgery who were Caucasian, privately insured, and of higher SES were more likely to seek preoperative second opinions, be prescribed a brace, and attend postoperative appointments. Recognition of the inherent health care disparities prevalent within each pediatric spine surgery referral region is imperative to better inform local and national institutional level programs to educate and assist patients and families most at risk for disparate access to scoliosis care. Level III; retrospective case-control study.

Caveats related to conduction system pacing utilizing a proprietary deflectable mapping catheter with a stylet-driven lead.

Hitherto, lumen less leads (LLLs) were routinely utilized for conduction system pacing (CSP). We report the largest experience using stylet-driven leads (SDLs) with a deflectable mapping catheter for CSP. Patients were prospectively and sequentially enrolled for CSP with SDL between June, 2021 and November, 2022 to (i) a novel deflectable mapping catheter (AgilisHisProTM, Abbott) (Group A) or (ii) a fixed curve sheath (Selectra3D, Biotronik) (Group B) in a 1:1 non-randomized fashion. The primary aim was to evaluate safety, feasibility, and efficacy of the CSP using SDL and deflectable mapping catheter (Group A) while reporting procedural success and intermediate-term follow-up. Seventy-nine patients (59.4%M, mean age 67.2+/-10.6 years) were allocated to either (i) Group A (n = 40) or (ii) Group B (n = 39). In Group A (n = 40, 50% M, mean age 67.2+/-9.5 years, follow-up 210.7 + 25.1days), His bundle pacing (HBP) was the default strategy with left bundle branch area pacing (LBBaP) for bailout. Procedural success with HBP was feasible in 17/40 (42.5%) patients with remaining 23/40 (57.5%) needing LBBaP bailout. After initial learning curve, a manual septal curve was introduced to successfully aid LBBaP in 6/23 (26.1%) cases. Procedural and follow-up parameters did not differ significantly in HBP vs. LBBaP. Head-to-head comparison was not performed between the groups owing to different default protocols (HBP-Group A, Discretionary-Group B). Use of SDL with single-curve deflectable mapping catheter was safe, feasible and yielded moderate procedural success with HBP and frequently needed a LBBaP bailout strategy. In approximately one-fourth of the latter, an out-of-plane manual septal curve was needed to optimize LBBaP.

Feasibility of common, enjoyable game play for assessing daily cognitive functioning in older adults.

Frequent digital monitoring of cognition is a promising approach for assessing endpoints in prevention and treatment trials of Alzheimer's disease and related dementias (ADRD). This study evaluated the feasibility of the MIND GamePack© for recurrent semi-passive assessment of cognition across a longitudinal interval. The MIND GamePack consists of four iPad-based games selected to be both familiar and enjoyable: Word Scramble, Block Drop, FreeCell, and Memory Match. Participants were asked to play 20 min/day for 5 days (100 min) for 4 months. Feasibility of use by older adults was assessed by measuring gameplay time and game performance. We also evaluated compliance through semi-structured surveys. A linear generalized estimating equation (GEE) model was used to analyze changes in gameplay time, and a regression tree model was employed to estimate the days it took for game performance to plateau. Subjective and environmental factors associated with gameplay time and performance were examined, including daily self-reported questions of memory and thinking ability, mood, sleep, energy, current location, and distractions prior to gameplay. Twenty-six cognitively-unimpaired older adults participated (mean age ± SD = 71.9 ± 8.6; 73% female). Gameplay time remained stable throughout the 4-months, with an average compliance rate of 91% ± 11% (1946 days of data across all participants) and weekly average playtime of 210 ± 132 min per participant. We observed an initial learning curve of improving game performance which on average, plateaued after 22-39 days, depending on the game. Higher levels of self-reported memory and thinking ability were associated with more gameplay time and sessions. MIND GamePack is a feasible and well-designed semi-passive cognitive assessment platform which may provide complementary data to traditional neuropsychological testing in research on aging and dementia.

Impact of Social Determinants of Health on Adolescent Idiopathic Scoliosis Curve Severity.

Social determinants of health have been shown to influence the health and outcomes of pediatric patients. Adolescent idiopathic scoliosis (AIS) may be particularly sensitive to such factors as early diagnosis and treatment can obviate the need for surgical intervention. The purpose of this study was to analyze the effect that social determinants of health have on the severity of AIS at presentation and at the time of surgery. A retrospective review was conducted for consecutive patients who underwent posterior spinal fusion for AIS from 2020 to 2022. Demographic data was collected, while insurance status (private vs. public) and childhood opportunity index (COI) categories (LOW vs. HIGH) were used as a proxy for socioeconomic status. Curve magnitude at the initial presentation and at the latest preoperative visit were recorded with a threshold of 25 to 40 degrees considered within the bracing range. Univariate and multivariate analysis was done to compare differences between subgroups as appropriate. A total of 180 patients with mean initial and preoperative major curve angles of 48 and 60 degrees were included. Statistically significant differences in race and insurance types were appreciated, with the LOW COI group having a higher proportion of underrepresented minority and publicly insured patients than the HIGH COI group ( P <0.001). Patients within the LOW COI group presented with an initial curve that was, on average, 6 degrees more severe than those within the HIGH group ( P =0.009) and a preoperative curve that was 4 degrees larger than those within the HIGH group ( P =0.015). Similarly, only 13% of patients within the LOW COI group presented with curves within the bracing threshold, compared with 31% in the HIGH COI group ( P =0.009). Socioeconomic status plays a significant role in the severity of AIS. Specifically, patients with lower COI tend to present with curve magnitudes beyond what is responsive to nonsurgical treatment, leading to larger curves at the time of surgery. Future work should focus on addressing social inequalities to optimize the treatment and outcomes of AIS patients. Level III- Retrospective Comparative Study.

Budget impact analysis of molecular subtype profiling in endometrial cancer

ObjectiveThis study evaluated the costs associated with four approaches to classifying endometrial cancer (EC), including histomorphological, histomorphological with ancillary immunohistochemical assays, histomolecular and selective molecular classification. MethodsDirect costs were determined per EC sample from the hospital's perspective. A budget impact analysis and sensitivity analysis were conducted to estimate the mean, minimum and maximum costs per sample and annual institutional costs in adjusted 2022 Canadian dollars. A provincial cost forecast was projected based on expected 2022 EC biopsies. ResultsIn 2018, our institution performed 190 EC biopsies. The mean cost per biopsy was $158 ($156–$212) for histomorphological classification, $384 ($360–$514) for histomorphological classification with immunohistochemistry and $1297 ($1265–1833) for histomolecular classification. Total annual institutional cost for histomorphological classification was $29,980 and $72,950 with immunohistochemistry. For histomolecular classification, the first year cost was $246,521, accounting for initial educational learning curve, and $233,461 thereafter, assuming a consistent number of biopsies per year. Targeted implementation of histomolecular classification among high-grade, p53 abnormal and/or MMR-deficient ECs (56% of cases) cost $169,688 in the first year and $162,418 annually thereafter. With a projected 3400 EC biopsies in Ontario in 2022, histomorphological classification would annually cost $537,078 and $1,305,677 with immunohistochemistry. Histomolecular classification would cost $4,410,203 in the first year and $4,176,737 annually once established. Selective molecular classification would lead to a cost of $3,044,178 in the first year and $2,913,443 thereafter. ConclusionsThe study highlights the need for informed decision-making when implementing molecular classification in clinical practice, given the substantial incremental healthcare costs associated with these approaches.

Procedural outcome and follow-up of stylet-driven leads compared with lumenless leads for left bundle branch area pacing.

Left bundle branch area pacing (LBBAP) is most often delivered using lumenless leads (LLLs), but may also be performed using stylet-driven leads (SDLs). There are limited reports on the comparison of these tools, mainly limited to reports describing initial operator experience or without detailed procedural data. Our aim was to perform an in-depth comparison of SDLs and LLLs for LBBAP at implantation and follow-up in a larger cohort of patients with experience that extends beyond that of the initial learning curve. A total of 306 consecutive patients (age 77 ± 11 years, 183 males) undergoing LBBAP implantation at a single centre were prospectively included. The population was split into two groups of 153 patients based on the initial use of an SDL (from 4 manufacturers) or an LLL. After having discounted the initial learning curve of 50 patients, there was no difference in the success rate between the initial use of lead type (96.0% with SDL vs. 94.3% with LLL, P = 0.56). There were no significant differences in success between lead models. Electrocardiogram and electrical parameters were comparable between the groups. Post-operative macro-dislodgement occurred in 4.3% of patients (essentially within the first day following implantation) and presumed micro-dislodgement with loss of conduction system capture or rise in threshold (occurring mostly during the first month) was observed in 4.7% of patients, without differences between groups. Left bundle branch area pacing may be safely and effectively performed using either LLLs or SDLs, which provides implanters with alternatives for delivering this therapy.

Removal of direct dyes from wastewater using chitosan and polyacrylamide blends

This study investigated the feasibility of employing neat chitosan powder, polyacrylamide, and chitosan micro-beads as adsorbents for the rapid and efficient removal of Direct Blue 78 dye from textile industrial wastewater. A series of batch experiments were conducted to examine the impact of adsorbent dose, contact time, and pH on the adsorption process. The physicochemical analysis, including FTIR, zeta potential analysis, and SEM were performed to identify the adsorption mechanism of chitosan powder and micro-beads. It was found that increasing the powder chitosan dose to 4.5 g/L and contact time up to 40 min resulted in achieving a significant increase in dye removal efficiency up to 94%. The highest removal efficiency of 94.2% was achieved at an initial dye concentration of 50 mg/L, a chitosan dosage of 4.5 g/L, and an optimized contact time of 60 min. Utilizing a polyacrylamide gel dose of 45 mL/L reduced the sedimentation time of chitosan from 8 h to 5 min. Equilibrium studies showed an initial L-shaped equilibrium curve, indicating that the adsorption process primarily arises from electrostatic interactions between dye molecules and adsorbent particles (physical forces). The Langmuir isothermal model demonstrated the best fit to the equilibrium data. Combining chitosan powder with polyacrylamide gel emerges as an economically viable choice for dye removal in industrial wastewater effluents, offering a cost-effective alternative to pricey commercial adsorbents. The results of the study revealed that the presence of polyacrylamide dye enhanced the removal efficiency and settling time of DB78 dye using chitosan.

Teaching Data Science with Literate Programming Tools

This paper presents a case study on using Emacs and Org-mode for literate programming in undergraduate computer and data science courses. Over three academic terms, the author mandated these tools across courses in R, Python, C++, SQL, and more. The onboarding relied on simplified Emacs tutorials and starter configurations. Students gained proficiency after undertaking initial practice. Live coding sessions demonstrated the flexible instruction enabled by literate notebooks. Assignments and projects required documentation alongside functional code. Student feedback showed enthusiasm for learning a versatile IDE, despite some frustration with the learning curve. Skilled students highlighted efficiency gains in a unified environment. However, the uneven adoption of documentation practices pointed to a need for better incorporation into grading. Additionally, some students found Emacs unintuitive, desiring more accessible options. This highlights a need to match tools to skill levels, potentially starting novices with graphical IDEs before introducing Emacs. The key takeaways are as follows: literate programming aids comprehension but requires rigorous onboarding and reinforcement, and Emacs excels for advanced workflows but has a steep initial curve. With proper support, these tools show promise for data science education.

LIMITATION OF PRIMERS USED IN PCR FOR THE CHARACTERIZATION OF LEISHMANIA INFANTUM.

Conventional PCR provides Leishmania species characterization with even a small amount of biological material. Species-specific primers have been a widely used alternative; however, nonspecific amplifications are a reality, interfering with PCR efficiency. In endemic areas with multiple etiological agents for leishmaniasis, there is a requirement for higher specificity of primers. This study evaluates 3 pairs of primers described for the identification and characterization of Leishmania infantum. Primers RV1/RV2, LEISH1/LEISH2, and FLC2/RLC2 were used with the DNA of L. infantum, Leishmania amazonensis, and Leishmania braziliensis. An initial temperature curve was performed (52-62 C) to determine the optimal annealing temperature, followed by a dilution curve of Leishmania DNA (500 pg/μl, 50 pg/μl, 5 pg/μl, 500 fg/μl, 50 fg/μl, 5 fg/μl, and 0.5 fg/μl) to be used for analytical sensitivity. RV1/RV2 PCR amplified L. infantum and L. amazonensis at all analyzed temperatures; LEISH1/LEISH2 PCR amplified all 3 species of Leishmania, although at some temperatures L. infantum was specifically amplified, and, finally, FLC2/RLC2 PCR amplified only L. infantum at all temperatures analyzed. In terms of sensitivity, RV1/RV2 PCR detected 1 fg of L. infantum DNA and 100 pg of L. amazonensis DNA; LEISH1/LEISH2 PCR detected 1 fg of L. infantum DNA, 100 fg of L. amazonensis DNA, and 10 fg of L. braziliensis DNA; and FLC2/RLC2 PCR detected 10 fg of L. infantum DNA. Thus, PCR with FLC2/RLC2 primers is best suited for the molecular characterization of L. infantum, especially in areas where there is an incidence of more than 1 Leishmania species, such as South America.

Initial Pressure Optimization of Thermal Power Unit under Deep Variable Operating Conditions

Aiming at the problem of how to adjust the main steam pressure under the load instruction from the frequency modulation of the power grid to make the operation safer and more economical in the process of peak regulation, we take that 650 MW reheating condensed steam turbine as the research object. This paper introduces some domestic scholars’ research status of initial pressure optimization. The model is established by using EBSILON Professional thermodynamic system simulation software and combining it with the heat balance diagram of the power plant under VWO working conditions. The initial pressure optimization under deep variable working conditions is studied, then introduces the operation mode of the steam turbine under variable working conditions during peak shaving. The mathematical relationship between heat consumption rate and initial pressure was established to determine the feasible range of initial pressure. The exhaustive method traverses the feasible pressure interval under a particular working condition. The heat consumption rate under each pressure was calculated to screen out the optimal initial pressure and optimize the initial pressure curve.

FEM Simulations of Fatigue Crack Initiation in the Oligocrystalline Microstructure of Stents.

For over two decades, vascular stents have been widely used to treat clogged vessels, serving as a scaffold to enlarge the narrowed lumen and recover the arterial flow area. High-purity oligocrystalline austenitic steel is usually applied for the production of stents. Despite the popularity and benefit of stenting, it still may cause serious clinical adverse issues, such as in-stent restenosis and stent fracture. Therefore, the study of the mechanical properties of stents and in particular the prediction of their life cycles are in the focus of materials research. In our contribution, within the finite element method, a two-scale model of crack initiation in the microstructure of stents is elaborated. The approach is developed on the basis of the physically based Tanaka-Mura model (TMM), considering the evolution of shear bands during the crack initiation phase. The model allows for the analysis of the microstructure with respect to the life cycles of real materials. The effects of different loading conditions, grain orientation, and thickness of the specimen on Wöhler curves were analysed. It was found that the microstructural features of oligocrystals are very sensitive to different loading conditions with respect to their fatigue behaviour and play a major role in fatigue crack initiation. Different grain-orientation distributions result in qualitative and quantitative differences in stress distribution and in the number of cycles for crack initiation. It was found that presence of a neutral zone in the cut-out of the microstructure under three-point-bending loading conditions changes the qualitative and quantitative patterns of stress distribution and affects the number of cycles for crack initiation. It was found that under both tensile and bending loading conditions, thicker specimens require more cycles for crack initiation. The Wöhler curves for crack initiation in oligocrystalline microstructures of stents could be compared with the ones in the experiment, taking into account that for high cyclic fatigue (HCF), typically, more than 70% of the cycles refer to crack initiation. The developed numerical tools could be used for the material design of stents.

Gasless laparoscopy in rural India-registry outcomes and evaluation of the learning curve

BackgroundA program of gasless laparoscopy (GL) has been implemented in rural North-East India. To facilitate safe adoption, participating rural surgeons underwent rigorous training prior to independent clinical practice. An online registry was established to capture clinical data on safety and efficacy and to evaluate initial learning curves for gasless laparoscopy.MethodsSurgeons who had completed the GL training program participated in the online RedCap Registry. Patients included in the registry provided informed consent for the use of their data. Data on operative times, conversion rates, perioperative complications, length of stay, and hospital costs were collected. Fixed reference cumulative sum (CUSUM) model was used to evaluate the learning curve based on operative times and conversion rates published in the literature.ResultsFour surgeons from three rural hospitals in North-East India participated in the registry. The data were collected over 12 months, from September 2019 to August 2020. One hundred and twenty-three participants underwent GL procedures, including 109 females (88.6%) and 14 males. GL procedures included cholecystectomy, appendicectomy, tubal ligation, ovarian cystectomy, diagnostic laparoscopy, and adhesiolysis. The mean operative time was 75.3 (42.05) minutes for all the surgeries. Conversion from GL to open surgery occurred in 11.4% of participants, with 8.9% converted to conventional laparoscopy. The main reasons for conversion were the inability to secure an operative view, lack of operating space, and adhesions. The mean length of stay was 3 (2.1) days. The complication rate was 5.7%, with one postoperative death. The CUSUM analysis for GL cholecystectomy showed a longer learning curve for operative time and few conversions. The learning curve for GL tubal ligation was relatively shorter.ConclusionGasless laparoscopy can be safely implemented in the rural settings of Northeast India with appropriate training programs. Careful case selection is essential during the early stages of the surgical learning curve.

Learning curves of robotic extended totally extraperitoneal (eTEP) hernia repair among two surgeons at a high-volume community hospital: a cumulative sum analysis.

Robotic extended totally extraperitoneal hernia (eTEP) repair is a novel technique for minimally invasive ventral hernia repair with retromuscular placement of mesh. This study aimed to evaluate the learning curve for robotic eTEP hernia repair using risk-adjusted cumulative sum (RA-CUSUM) analysis for two general surgeons-one with dedicated fellowship training in robotic eTEP technique (surgeon 2) and another without robotic eTEP-specific training (surgeon 1). We conducted a retrospective analysis of 98 patients undergoing robotic eTEP hernia repair from July 2020 to February 2022 for two surgeons. RA-CUSUM method was applied to the overall operative time (OT) in minutes, adjusting for transversus abdominis release (TAR). Figures 3 (surgeon 1) and 4 (surgeon 2) illustrate the three phases in the RA-CUSUM graphs of OT. For surgeon 1, the cases for each phase were determined: phase 1 (1 to 12), phase 2 (13 to 24), and phase 3 (25 to 51). For surgeon 2, the three phases were similarly determined as 1 to 8, 9 to 32, and 33 to 47, respectively. A significant (p = 0.017) difference existed for the OTs between phases 1 (262 ± 69) and 3 (192 ± 63.0) for surgeon 1. OT compared to the risk-adjusted value stabilized after case 12 and decreased after case 24 for surgeon 1; it began to decrease after case 8 for surgeon 2. The initial learning curve for surgeon 1 reached its plateau after 12 cases, shorter than comparable studies. This was likely due to the surgeon's intentional focus on learning this technique through courses, proctoring, and active mentorship. The flat learning curve seen in surgeon 2's series illustrates the value of experience gained during fellowship training. Our data support that, given the right resources and support, a short learning curve for eTEP is attainable for community surgeons without prior training in the technique.

The evolution of gradient flow minimizing the anisoperimetric ratio of convex plane curves

In this paper, we study the evolution of the gradient flow minimizing the anisoperimetric ratio of convex plane curves. It is shown that for any closed embedded initial curve, which is smooth and convex, the flow exists for all time and the evolving curves converge smoothly to a homothety of boundary of the Wulff shape, which is determined by anisotropic function.

Transformer modelling considering power losses using an inverse Jiles-Atherton approach

Power transformers are devices with non-linear behavior due to the saturation of the ferromagnetic core. When modelling such devices, the saturation effect must be taken into account because it greatly affects their performance and efficiency. In this paper, an electromagnetic model for power transformers is proposed and experimentally validated using an electrical T-model coupled with a reluctance network to model the magnetic part. The electrical circuit and the reluctance network are linked by two B–H approaches. The B–H relationships are modelled by the full hysteresis cycle based on the inverse Jiles-Atherton theory and by the initial magnetization curve. The results obtained with the inverse Jiles-Atherton theory model reproduce the magnetic core behavior with more accuracy than the one based on the initial magnetization curve, especially at low load conditions where saturation plays a more prominent role on the no-load current. The proposed model can be applied to other magnetic devices such as inductors for power electronic applications or electromechanical relays, among others.