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underwent ileostomy reversal in June 2020. He is currently under surveillance with normal CEA and no radiographic evidence of disease. He experiences urgency and clustering of bowel movements, consistent with low anterior resection syndrome.

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We present computational studies of quasi three-dimensional nanowell (NW) and nanopost (NP) plasmonic crystals for applications in surface enhanced Raman spectroscopy (SERS). The NW and NP plasmonic crystals are metal coated arrays of cylindrical voids or posts, respectively, in a dielectric substrate characterized by a well/post diameter (D), relief depth (RD), periodicity (P), and metal thickness (MT). Each plasmonic crystal is modeled using the three-dimensional finite-difference time-domain (FDTD) method with periodic boundary conditions in the x- and y-directions applied to a computational unit cell to simulate the effect of a periodic array. Relative SERS responses are calculated from time-averaged electric field intensity enhancements at λexc and λscat or at λmid via GSERS4=g2(λexc)×g2(λscat) or Gmid4=g4(λmid), respectively, where g2=|E|2/|E0|2. Comparisons of GSERS4 and Gmid4 are made to previously reported experimental SERS measurements for NW and NP geometries. Optimized NW and NP configurations based on variations of D, P, RD, and MT using GSERS4 are presented, with 6× and 2× predicted increases in SERS, respectively. A novel plasmonic crystal based on square NP geometries are considered with an additional 3× increase over the optimized cylindrical NP geometry. NW geometries with imbedded spherical gold nanoparticles are considered, with 10× to 103× increases in SERS responses over the NW geometry alone. The results promote the use of FDTD as a viable in silico route to the design and optimization of SERS active devices.

Introduction Peroral endoscopic myotomy (POEM) is a novel endoscopic procedure used to treat achalasia and other spastic esophageal disorders that is an alternative to Heller myotomy. We seek to define the learning curve of POEM for a foregut surgeon with no formal endoscopic or POEM training by analyzing different intraoperative factors in a single series. Methods and Procedures The first 38 consecutive patients undergoing POEM by a single foregut surgeon were included in this retrospective study. Inverse curve regression models were used to analyze total operative time (TOT) and total operative time per centimeter of myotomy (TOT-CM), in addition to other intraoperative variables. Clinical outcomes were reported as pre- and post-operative Eckardt Scores. Results All patients had type II achalasia with no post-operative complications observed. Eckardt scores improved postoperatively (median (range): 1 (0-4)) compared with the preoperative scores (10 (8-12)) (P < .001). The total operative time (median 76 minutes, range 51-129) decreased significantly over the course of the series (R2 = .38, P < .001), with a learning plateau at 70 minutes and a learning rate of 12 cases. Total operative time per centimeter of myotomy (median 7.08 min/cm, range 4.25 to 15.38) decreased over time (R2 = .45, P < .001), with a learning plateau at 7 minutes/cm and a learning rate of 12 cases. Conclusion The number of cases for a foregut surgeon to become proficient in a POEM procedure was found to be 12-14 cases. The learning curve for a POEM in a formally trained foregut surgeon may be comparable to an endoscopically trained interventionist.