Educational and Patient Care Impacts of In Situ Simulation in Healthcare: A Systematic Review.

ABSTRACT: This systematic review was performed to assess the effectiveness of in situ simulation education. We searched databases including MEDLINE and Embase for studies comparing in situ simulation with other educational approaches. Two reviewers screened articles and extracted information. Sixty-two articles met inclusion criteria, of which 24 were synthesized quantitatively using random effects meta-analysis. When compared with current educational practices alone, the addition of in situ simulation to these practices was associated with small improvements in clinical outcomes, including mortality [odds ratio, 0.66; 95% confidence interval (CI), 0.55 to 0.78], care metrics (standardized mean difference, -0.34; 95% CI, -0.45 to -0.21), and nontechnical skills (standardized mean difference, -0.52; 95% CI, -0.99 to -0.05). Comparisons between in situ and traditional simulation showed mixed learner preference and knowledge improvement between groups, while technical skills showed improvement attributable to in situ simulation. In summary, available evidence suggests that adding in situ simulation to current educational practices may improve patient mortality and morbidity.

Matrix Analysis of Warped Stretch Imaging.

Sensitive and fast optical imaging is needed for scientific instruments, machine vision, and biomedical diagnostics. Many of the fundamental challenges are addressed with time stretch imaging, which has been used for ultrafast continuous imaging for a diverse range of applications, such as biomarker-free cell classification, the monitoring of laser ablation, and the inspection of flat panel displays. With frame rates exceeding a million scans per second, the firehose of data generated by the time stretch camera requires optical data compression. Warped stretch imaging technology utilizes nonuniform spectrotemporal optical operations to compress the image in a single-shot real-time fashion. Here, we present a matrix analysis method for the evaluation of these systems and quantify important design parameters and the spatial resolution. The key principles of the system include (1) time/warped stretch transformation and (2) the spatial dispersion of ultrashort optical pulse, which are traced with simple computation of ray-pulse matrix. Furthermore, a mathematical model is constructed for the simulation of imaging operations while considering the optical and electrical response of the system. The proposed analysis method was applied to an example time stretch imaging system via simulation and validated with experimental data.

Context-Aware Image Compression.

We describe a physics-based data compression method inspired by the photonic time stretch wherein information-rich portions of the data are dilated in a process that emulates the effect of group velocity dispersion on temporal signals. With this coding operation, the data can be downsampled at a lower rate than without it. In contrast to previous implementation of the warped stretch compression, here the decoding can be performed without the need of phase recovery. We present rate-distortion analysis and show improvement in PSNR compared to compression via uniform downsampling.

Digitally synthesized beat frequency-multiplexed fluorescence lifetime spectroscopy.

Frequency domain fluorescence lifetime imaging is a powerful technique that enables the observation of subtle changes in the molecular environment of a fluorescent probe. This technique works by measuring the phase delay between the optical emission and excitation of fluorophores as a function of modulation frequency. However, high-resolution measurements are time consuming, as the excitation modulation frequency must be swept, and faster low-resolution measurements at a single frequency are prone to large errors. Here, we present a low cost optical system for applications in real-time confocal lifetime imaging, which measures the phase vs. frequency spectrum without sweeping. Deemed Lifetime Imaging using Frequency-multiplexed Excitation (LIFE), this technique uses a digitally-synthesized radio frequency comb to drive an acousto-optic deflector, operated in a cat's-eye configuration, to produce a single laser excitation beam modulated at multiple beat frequencies. We demonstrate simultaneous fluorescence lifetime measurements at 10 frequencies over a bandwidth of 48 MHz, enabling high speed frequency domain lifetime analysis of single- and multi-component sample mixtures.