Background Biopsy surveillance protocols for the assessment of Barrett’s esophagus can be subject to sampling errors, resulting in diagnostic uncertainty. Optical coherence tomography is a cross-sectional imaging technique that can be used to conduct volumetric laser endomicroscopy (VLE) of the entire distal esophagus. We have developed a biopsy guidance platform that places endoscopically visible marks at VLE-determined biopsy sites. Objective The objective of this study was to demonstrate in human participants the safety and feasibility of VLE-guided biopsy in vivo. Design A pilot feasibility study. Setting Massachusetts General Hospital. Patients A total of 22 participants were enrolled from January 2011 to June 2012 with a prior diagnosis of Barrett’s esophagus. Twelve participants were used to optimize the laser marking parameters and the system platform. A total of 30 target sites were selected and marked in real-time by using the VLE-guided biopsy platform in the remaining 10 participants. Intervention Volumetric laser endomicroscopy. Main Outcome Measurements Endoscopic and VLE visibility, and accuracy of VLE diagnosis of the tissue between the laser cautery marks. Results There were no adverse events of VLE and laser marking. The optimal laser marking parameters were determined to be 2 seconds at 410 mW, with a mark separation of 6 mm. All marks made with these parameters were visible on endoscopy and VLE. The accuracies for diagnosing tissue in between the laser cautery marks by independent blinded readers for endoscopy were 67% (95% confidence interval [CI], 47%–83%), for VLE intent-to-biopsy images 93% (95% CI, 78%–99%), and for corrected VLE post-marking images 100% when compared with histopathology interpretations. Limitations This is a single-center feasibility study with a limited number of patients. Conclusion Our results demonstrate that VLE-guided biopsy of the esophagus is safe and can be used to guide biopsy site selection based on the acquired volumetric optical coherence tomography imaging data. (Clinical trial registration number: NCT01439633.)

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The individual pursuit is a 4-km cycling time trial performed on a velodrome. Parathletes with transtibial amputation (TTA) have lost physiological systems, but this may be offset by the reduced aerodynamic drag of the prosthesis. This research was performed to understand the effect of a unilateral TTA on Olympic 4-km pursuit performance. A forward-integration model of pursuit performance explored the interplay between power loss and aerodynamic gains in parathletes with TTA. The model is calibrated to a 4-km pursuit time of 4:10.5 (baseline), then adjusted to account for a TTA. Conditions simulated were based on typical pedal asymmetry in TTA (AMP), if foot stiffness were decreased (FLEX), if pedaling asymmetries were minimized (ASYM), if the prosthesis were aerodynamically optimized (AERO), if the prosthesis had a cosmetic cover (CC), and if all variables were optimized (OPT). A random Monte Carlo analysis was performed to understand model precision. Four-kilometer pursuit performances predicted by the model were 4:10.5, 4:20.4, 4:27.7, 4:09.2, 4:19.4, 4:27.9, and 4:08.2 for the baseline, AMP, FLEX, ASYM, AERO, CC, and OPT models, respectively. Model precision was ±3.7 s. While the modeled time decreased for ASYM and OPT modeled conditions, the time reduction fell within model precision and therefore was not significant. Practical application of these results suggests that parathletes with a TTA could improve performance by minimizing pedaling asymmetry and/or optimizing aerodynamic design, but, at best, they will have performance similar to that of intact cyclists. In conclusion, parathletes with TTA do not have a net advantage in the individual pursuit.

Summary The low Mach number performance of the MacCormack scheme is examined. The inherent dissipation in the scheme is found to suffer from the degradation in accuracy observed with traditional, density‐based methods for compressible flows. Two specific modifications are proposed, leading to the formation of the generalized MacCormack scheme within a dual‐time framework (called GMC‐PC). The first modification involves reformulating the flux by splitting it into particle convection and acoustic parts, with the former terms treated using the traditional MacCormack discretization and the latter terms augmented by the addition of a pressure‐based artificial dissipation. The second modification involves a reformulation of the traditional nonlinear fix introduced by MacCormack in 1971, which is found to be necessary to suppress pressure oscillations at low Mach numbers. The new scheme is demonstrated to have superior performance, independent of Mach number, compared with standard MacCormack implementations using several canonical test problems. Copyright © 2017 John Wiley & Sons, Ltd.