Endoscopic submucosal dissection: a cognitive task analysis framework toward training design.

BACKGROUND: One of the major impediments to the proliferation of endoscopic submucosal dissection (ESD) training in Western countries is the lack of sufficient experts as instructors. One way to address this gap is to develop didactic systems, such as surgical simulators, to support the role of trainers. Cognitive task analysis (CTA) has been used in healthcare for the design and improvement of surgical training programs, and therefore can potentially be used for design of similar systems for ESD. OBJECTIVE: The aim of the study was to apply a CTA-based approach to identify the cognitive aspects of performing ESD, and to generate qualitative insights for training. MATERIALS AND METHODS: Semi-structured interviews were designed based on the CTA framework to elicit knowledge of ESD practitioners relating to the various tasks involved in the procedure. Three observations were conducted of expert ESD trainers either while they performed actual ESD procedures or at a training workshop. Interviews were either conducted over the phone or in person. Interview participants included four experts and four novices. The observation notes and interviews were analyzed for emergent qualitative themes and relationships. RESULTS: The qualitative analysis yielded thematic insights related to four main cognition-related categories: learning goals/principles, challenges/concerns, strategies, and decision-making. The specific insights under each of these categories were systematically mapped to the various tasks inherent to the ESD procedure. CONCLUSIONS: The CTA approach was applied to identify cognitive themes related to ESD procedural tasks. Insights developed based on the qualitative analysis of interviews and observations of ESD practitioners can be used to inform the design of ESD training systems, such as virtual reality-based simulators.

A task and performance analysis of endoscopic submucosal dissection (ESD) surgery.

BACKGROUND: ESD is an endoscopic technique for en bloc resection of gastrointestinal lesions. ESD is a widely-used in Japan and throughout Asia, but not as prevalent in Europe or the US. The procedure is technically challenging and has higher adverse events (bleeding, perforation) compared to endoscopic mucosal resection. Inadequate training platforms and lack of established training curricula have restricted its wide acceptance in the US. Thus, we aim to develop a Virtual Endoluminal Surgery Simulator (VESS) for objective ESD training and assessment. In this work, we performed task and performance analysis of ESD surgeries. METHODS: We performed a detailed colorectal ESD task analysis and identified the critical ESD steps for lesion identification, marking, injection, circumferential cutting, dissection, intraprocedural complication management, and post-procedure examination. We constructed a hierarchical task tree that elaborates the order of tasks in these steps. Furthermore, we developed quantitative ESD performance metrics. We measured task times and scores of 16 ESD surgeries performed by four different endoscopic surgeons. RESULTS: The average time of the marking, injection, and circumferential cutting phases are 203.4 (σ: 205.46), 83.5 (σ: 49.92), 908.4 s. (σ: 584.53), respectively. Cutting the submucosal layer takes most of the time of overall ESD procedure time with an average of 1394.7 s (σ: 908.43). We also performed correlation analysis (Pearson's test) among the performance scores of the tasks. There is a moderate positive correlation (R = 0.528, p = 0.0355) between marking scores and total scores, a strong positive correlation (R = 0.7879, p = 0.0003) between circumferential cutting and submucosal dissection and total scores. Similarly, we noted a strong positive correlation (R = 0.7095, p = 0.0021) between circumferential cutting and submucosal dissection and marking scores. CONCLUSIONS: We elaborated ESD tasks and developed quantitative performance metrics used in analysis of actual surgery performance. These ESD metrics will be used in future validation studies of our VESS simulator.

[Stability Study of Nano-Silver Particles Dispersed in Various Solvents by Turbiscan Lab Optical Analyzer].

Nano-silver particles were synthesized through chemical reduction method, using silver nitrate, m-dihydroxybenzene and polyvinylpyrrolidone as silver source, reduction agent and protective agent respectively; and redundant reactants were removed through centrifugation and washing operation. Then different nano-silver colloids were acquired by dispersing the nano-silver particles in water, ethanol and ethylene glycol respectively through ultrasonic dispersion. For comparison, the nano-silver particles mass fraction of all the colloids was 0.2 Wt% during the research. Nano-silver particles were characterized by laser particle size analyzer, transmission electron microscopy (TEM) and scanning electron microscopy (SEM); and the concentration of nano-silver colloids was confirmed through synchronized thermal analyzer (STA). The size distribution result of laser particle size analyzer showed that nano-silver particles were about 100 nm and had uniform size distribution. The images of TEM and SEM showed that the size of nano-silver particles was in nanoscale as well. To evaluate the dispersion stabilities of different nano-silver colloids, Turbiscan optical analyzer which was based on multiple light scattering analysis had been employed in the research; and the principle factors leading to instabilities of nano-silver colloids were also discussed. Results showed that particle size variation and particle migration were major factors which affected the dispersion stabilities of nano-silver colloids. For the nano-silver colloid dispersed in water phase, the backscattering light signal in middle of the sample cell stayed unchanged with time while the backscattering light signals at top and bottom of the sample cell showed dramatic variation during the measurement, which indicated that particle migration was the main reason why the nano-silver colloids was unstable. But for the nano-silver colloids dispersed in ethanol and ethylene glycol phase, the backscattering light signals in bottom, middle and top of the sample cell presented obvious variation at the end of the tests, which certificated that both particle size variation and particle migration affected the stabilities of nano-silver colloids. At last, by comparing the Turbiscan Stability Index (TSD of three different nano-silver colloids, the stabilities of the systems were outlined by a descending order: ethylene glycol, water and ethanol.

Validation of a Virtual Simulator With Haptic Feedback for Endotracheal Intubation Training.

INTRODUCTION: Endotracheal intubation (ETI) is a procedure that varies in difficulty because of patient characteristics and clinical conditions. Existing physical simulators do not encompass these variations. The Virtual Airway Skills Trainer for Endotracheal Intubation (VAST-ETI) was developed to provide different patient characteristics and high-fidelity haptic feedback to improve training. METHODS: We demonstrate the effectiveness of VAST-ETI as a training and evaluation tool for ETI. Construct validation was evaluated by scoring the performance of experts ( N = 15) and novices ( N = 15) on the simulator to ensure its ability to distinguish technical proficiency. Convergent and predictive validity were evaluated by performing a learning curve study, in which a group of novices ( N = 7) were trained for 2 weeks using VAST-ETI and then compared with a control group ( N = 9). RESULTS: The VAST-ETI was able to distinguish between expert and novice based on mean simulator scores ( t [88] = -6.61, P < 0.0005). When used during repeated practice, individuals demonstrated a significant increase in their score on VAST-ETI over the learning period ( F [11,220] = 7206, P < 0.001); however when compared with a control group, there was not a significant interaction effect on the simulator score. There was a significant difference between the simulator-trained and control groups ( t [12.85] = -2.258, P = 0.042) when tested in the operating room. CONCLUSIONS: Our results demonstrate the effectiveness of virtual simulation with haptic feedback for assessing performance and training of ETI. The simulator was not able to differentiate performance between more experienced trainees and experts because of limits in simulator difficulty.

Research on sand body architecture at the intersection of a bidirectional sedimentary system in the Jiyuan area of Ordos Basin.

The exploration and development of the dual-provenance lower assemblage of the Yanchang Formation in the Jiyuan area has progressed rapidly. At the intersection of this bidirectional provenance system, a complex and variable spatial combination of sand bodies formed, resulting in significant structural heterogeneity in the development and distribution of reservoirs. Based on previous studies, this paper combines core data and logging data with a large number of analytical tests and production performance data to carry out research on the Chang 82-Chang 9 reservoir group in the lower assemblage of the Yanchang Formation in the Shijiawan-Buziwan area. Based on the analysis of sedimentary conditions, the sand body development pattern at the intersection of the bidirectional sedimentary system in the study area was analysed by stepwise dissection of the sand body architecture. After the types and characteristics of the 4th- to 5th-level architectural elements were determined, the spatial distribution of the combinations of these elements was assessed and combined with logging discriminant analysis and geometric shape prediction methods to identify a 'prism' architectural distribution pattern. The architectural elements are connected with the distribution of diagenetic facies, the spatial distribution patterns of different types of diagenetic facies under the constraints of the architecture are summarized by region, and the locations of potential favourable reservoir development are discussed. The results show that the degree of superposition and combination of the eight skeletal architectural elements in the target layers gradually deteriorate from the bottom to the top. In addition, the development scale and degree of architectural elements in the braided river delta system in the west are better than those in the meandering river delta system in the east. In the different sedimentary areas, the spatial combination styles of the architectural elements are quite different, and the combination of these elements gradually changes from a combination of braided channels (FA1) and abandoned channels (FA2) to a combination of underwater distributary channels (FA4). Matching of the distribution of diagenetic facies with the distribution of architectural elements reveals that the diagenetic facies dominated by intergranular pores and dissolution pores (associated with good reservoir physical properties) are usually found at the bottom or in the lower to middle parts of the skeletal architectural elements.

Deep learning time series prediction models in surveillance data of hepatitis incidence in China.

BACKGROUND: Precise incidence prediction of Hepatitis infectious disease is critical for early prevention and better government strategic planning. In this paper, we presented different prediction models using deep learning methods based on the monthly incidence of Hepatitis through a national public health surveillance system in China mainland. METHODS: We assessed and compared the performance of three deep learning methods, namely, Long Short-Term Memory (LSTM) prediction model, Recurrent Neural Network (RNN) prediction model, and Back Propagation Neural Network (BPNN) prediction model. The data collected from 2005 to 2018 were used for the training and prediction model, while the data are split via 5-Fold cross-validation. The performance was evaluated based on three metrics: mean square error (MSE), mean absolute error (MAE), and mean absolute percentage error (MAPE). RESULTS: Among the year 2005-2018, 20,924,951 cases and 11,892 deaths were supervised in the system. Hepatitis B (HB) is the most disease-causing incidence and death, and the proportion is greater than 70 percent, while the percentage of the incidence and deaths is decreased much in 2018 compared with 2005. Based on the measured errors and the visualization of the three neural networks, there is no one model predicting the incidence cases that can be completely superior to other models. When predicting the number of incidence cases for HB, the performance ranking of the three models from high to low is LSTM, BPNN, RNN, while it is LSTM, RNN, BPNN for Hepatitis C (HC). while the MAE, MSE and MAPE of the LSTM model for HB, HC are 3.84*10-06, 3.08*10-11, 4.981, 8.84*10-06, 1.98*10-12,5.8519, respectively. CONCLUSIONS: The deep learning time series predictive models show their significance to forecast the Hepatitis incidence and have the potential to assist the decision-makers in making efficient decisions for the early detection of the disease incidents, which would significantly promote Hepatitis disease control and management.

Attenuation of the Bauschinger effect and enhancement of tension-compression asymmetry in single crystal aluminum by temperature.

Temperature has a great influence on the mechanical properties of nano-materials. The molecular dynamics method was used to study the effect of temperature on the tension-compression asymmetry and Bauschinger effect of nano single crystal aluminum (NSCA). The strain-hardening behavior of NSCA in the tensile plastic stage is significantly enhanced when the temperature is higher than 400 K. The plastic deformation mechanism of tensile loading shifts from slip blocking of dislocations in grains to dislocation nucleation. The degradation of the mechanical properties of NSCA under compressive loading increases gradually with the increase of temperature. Dislocation emission is limited under compressive loading. Nonetheless, plastic deformation may still be regulated by dislocation slip during severe plastic deformation stages and at elevated temperatures. Temperature enhancement can effectively promote the movement of pre-dislocations and eliminate residual stresses. A new microscopic insight into the temperature attenuated Bauschinger effect is provided. This study provides important theoretical guidance for a comprehensive and in-depth understanding of the high-temperature mechanical properties and microstructure evolution mechanism of NSCA.

Experimental Comparative Investigation of Hot Solvent/Steam-Assisted Gravity Drainage in Oil Sand Reservoirs.

Hot solvent-assisted gravity drainage (HS-AGD) is an effective way to exploit oil sands and heavy oil both economically and environmentally. The visualized microscopic seepage experiments and two-dimensional (2-D) macroscopic simulation experiments of HS-AGD are carried out, and the results are compared with that of steam-assisted gravity drainage (SAGD) in detail for the first time in order to compare their development effects of the oil sand reservoir. MacKay River oil sand bitumen is taken as an oil sample in the experiments, with n-hexane as the solvent. Micro seepage characteristics of the hot solvent and steam and the remaining oil distribution of the solvent and steam drive are investigated through microseepage experiments. The expanding process of the solvent/steam chamber and production performance of HS-SAGD and SAGD are investigated through macrosimulation experiments. The study found that the sweep efficiency of hot solvent is higher than that of steam at the same temperature due to the small interfacial tension between the condensed solvent and heated bitumen. Due to the severe gravity segregation, the steam accumulated at the top of the model during the 2-D physical simulation experiment, which results in the huge heat loss at the top of the model. The temperature of the steam chamber is significantly lower than that of the solvent chamber. The oil recovery of 200 °C hot solvent vapor is twice as much as that of 300 °C steam owing to the different drainage mechanisms of the HS-AGD and SAGD. In SAGD, only heat transfer reduces the viscosity of oil sand bitumen. The components of oil produced in SAGD have little difference compared with that of the original bitumen. In HS-AGD, both mass transfer and the sensible heat transfer reduce the viscosity of oil sand bitumen. The in situ asphaltene precipitation induced by heated-solvent extraction also upgrades the bitumen. The results of component analysis show that in HS-AGD, the content of heavy components in the oil sand bitumen is obviously reduced. This paper aims to reveal the oil drainage mechanism of HS-AGD and SAGD from the macroscopic and microscopic view and to provide theoretical guidance for the field application of this technology.

Pore Size Distribution Characteristics of High Rank Coal with Various Grain Sizes.

Particle void filling effects (P f) under low pressure and coal matrix compressibility effects (P c) at high pressure should not be ignored when using mercury intrusion porosimetry (MIP) to study the pore size distribution of coal. In this study, two coal samples (FX and HF) collected from western Guizhou were crushed into three different grain sizes; then, the subsamples were analyzed by MIP and low-pressure nitrogen adsorption to study the pore size distribution characteristics. The micro- and transition pore volumes contribute to the total pore volume of the FX and HF subsamples. With decreasing subsample grain sizes, the macropore volume of FX subsamples tends to increase, while mesopore volume decreases; the volumes of micropores and transition pores first increase and then decrease. In regard to the HF subsamples, the volumes of macropores and mesopores do not reveal any distinctive changes, while the 40-60 mesh subsample contains the greatest volume of micropores and transition pores. Fractal theory was introduced to determine P f and P c. P f barely changed as grain size decreased; it ranged from 0.1 to 0.15 MPa. However, P c increased with reduced coal grain sizes. The coal matrix compressibility coefficients of the subsamples were calculated from the cumulative mercury volume curve, and the true pore volume was also modified. The modified volume of macropores does not change markedly, while the volumes of mesopores and transition pores decrease significantly, clearly indicating the coal matrix compressibility under high mercury injection pressure. The modified pore volume shows that the pore (<10,000 nm) still harbors fractal characteristics.

Development of an Endotracheal Intubation Formative Assessment Tool.

BACKGROUND: Valid methods for providing detailed formative feedback on direct laryngoscopy and endotracheal intubation (ETI) performance do not exist. We are developing an observation-based assessment tool for measuring performance and providing feedback during ETI. METHODS: Based on the literature and interviews of experts, we proposed an initial ETI metric with 22 items. Six anesthesiology experts used it to assess the quality of ETI performance in videotaped intubations. Following metric revisions, 2 expert groups assessed 2 collections of videos (27 total) using the revised metric. Two reference standards for comparison with metric scores were created with a third and fourth group of experts; (1) an average global rating (1-100) of each ETI performance and (2) average rank-ordered performance from best to worst. Rater agreement and correlations between the 2 methods were calculated. Regression analysis determined items that optimally discriminated quality. When calculating a score based on all clinically important terms, multiple weightings were evaluated. RESULTS: Metric items had high average rater agreement (80%) with intraclass correlation coefficients averaging 0.83. Correlations of the reference rank and score were high for both video collections (-0.96, P < .05, and -0.95, P < .05). Regression coefficients for different item weighting methods indicated strong relationships with global ratings (averaging r = 0.89, P < .05) and rankings averaging -0.85, P < .05). Prediction of global ratings using regression achieved high accuracy (R 2 = 0.8218). CONCLUSIONS: High observer agreement and strong correlations between metric and rank data support the validity of using this metric to assess ETI performance. Different weighting models yielded scores that correlated strongly with the ratings and ranks from global assessment. When using the metric to predict competency, a 3-item regression model is most accurate in predicting a global score.

The inhibitory impacts of nano-graphene oxide on methane production from waste activated sludge in anaerobic digestion.

The wide application of graphene oxide nanoparticles inevitably leads to their discharge into wastewater treatment plants and combination with the activated sludge. However, to date, it is largely unknown if the nano-graphene oxide (NGO) has potential impacts on the anaerobic digestion of waste activated sludge (WAS). Therefore, this work aims to fill the knowledge gap through comprehensively investigating the effects of NGO on carbon transformation and methane production in the anaerobic digestion of WAS. Biochemical methane potential tests demonstrated the methane production dropped with increasing NGO additions, the cumulative methane production decreasing by 7.6% and 12.6% at the NGO dosing rates of 0.054 mg/mg-VS and 0.108 mg/mg-VS, respectively. Model-based analysis indicated NGO significantly reduced biochemical methane potential, with the highest biochemical methane potential decrease being approximately 10% at the highest NGO dosing rate. Further experimental analysis suggested that the decreased methane production was firstly related to a decrease in soluble organic substrates availability during the process of sludge disintegration, potentially attributing to the strong absorption of organic substrates by NGO. Secondly, NGO significantly inhibited the methanogenesis by negatively affecting the corresponding enzyme activity (i.e. coenzyme F420), which could also resulted in a decreased methane production.