Search

Accurate prediction of postoperative mortality is important for not only successful postoperative patient care but also for information-based shared decision-making with patients and efficient allocation of medical resources. This study aimed to create a machine-learning prediction model for 30-day mortality after a non-cardiac surgery that adapts to the manageable amount of clinical information as input features and is validated against multi-centered rather than single-centered data. Data were collected from 454,404 patients over 18 years of age who underwent non-cardiac surgeries from four independent institutions. We performed a retrospective analysis of the retrieved data. Only 12–18 clinical variables were used for model training. Logistic regression, random forest classifier, extreme gradient boosting (XGBoost), and deep neural network methods were applied to compare the prediction performances. To reduce overfitting and create a robust model, bootstrapping and grid search with tenfold cross-validation were performed. The XGBoost method in Seoul National University Hospital (SNUH) data delivers the best performance in terms of the area under receiver operating characteristic curve (AUROC) (0.9376) and the area under the precision-recall curve (0.1593). The predictive performance was the best when the SNUH model was validated with Ewha Womans University Medical Center data (AUROC, 0.941). Preoperative albumin, prothrombin time, and age were the most important features in the model for each hospital. It is possible to create a robust artificial intelligence prediction model applicable to multiple institutions through a light predictive model using only minimal preoperative information that can be automatically extracted from each hospital. [ABSTRACT FROM AUTHOR]

Grating interferometry is a promising technique to obtain differential phase contrast images with illumination source of low intrinsic transverse coherence. However, retrieving the phase contrast image from the differential phase contrast image is difficult due to the accumulated noise and artifacts from the differential phase contrast image (DPCI) reconstruction. In this paper, we implemented a deep learning-based phase retrieval method to suppress these artifacts. Conventional deep learning based denoising requires noise/clean image pair, but it is not feasible to obtain sufficient number of clean images for grating interferometry. In this paper, we apply a recently developed neural network called Noise2Noise (N2N) that uses noise/noise image pairs for training. We obtained many DPCIs through combination of phase stepping images, and these were used as input/target pairs for N2N training. The application of the N2N network to simulated and measured DPCI showed that the phase contrast images were retrieved with strongly suppressed phase retrieval artifacts. These results can be used in grating interferometer applications which uses phase stepping method. [ABSTRACT FROM AUTHOR]

We describe an inverse Talbot–Lau neutron grating interferometer that provides an extended autocorrelation length range for quantitative dark-field imaging. To our knowledge, this is the first report of a Talbot–Lau neutron grating interferometer (nTLI) with inverse geometry. We demonstrate a range of autocorrelation lengths (ACL) starting at low tens of nanometers, which is significantly extended compared to the ranges of conventional and symmetric setups. ACLs from a minimum of 44 nm to the maximum of 3.5 μm were presented for the designed wavelength of 4.4 Å in experiments. Additionally, the inverse nTLI has neutron-absorbing gratings with an optically thick gadolinium oxysulfide (Gadox) structure, allowing it to provide a visibility of up to 52% while maintaining a large field of view of approximately 100 mm × 100 mm. We demonstrate the application of our interferometer to quantitative dark-field imaging by using diluted polystyrene particles in an aqueous solution and silicon comb structures. We obtain quantitative structural information of the sphere size and concentration of diluted polystyrene particles and the period, height, and duty cycle of the silicon comb structures. The optically thick Gadox structure of the analyzer grating also provides improved characteristics for the correction of incoherent neutron scattering in an aqueous solution compared to the symmetric nTLI. [ABSTRACT FROM AUTHOR]

In the past decade neutron dark-field contrast imaging has developed from a qualitative tool depicting microstructural inhomogeneities in bulk samples on a macroscopic scale of tens to hundreds of micrometers to a quantitative spatial resolved small-angle scattering instrument. While the direct macroscopic image resolution around tens of micrometers remains untouched microscopic structures have become assessable quantitatively from the nanometer to the micrometer range. Although it was found that magnetic structures provide remarkable contrast we could only recently introduce polarized neutron grating interferometric imaging. Here we present a polarized and polarization analyzed dark-field contrast method for spatially resolved small-angle scattering studies of magnetic microstructures. It is demonstrated how a polarization analyzer added to a polarized neutron grating interferometer does not disturb the interferometric measurements but allows to separate and measure spin-flip and non-spin-flip small-angle scattering and thus also the potential for a distinction of nuclear and different magnetic contributions in the analyzed small-angle scattering. [ABSTRACT FROM AUTHOR]

In this study, the spatio-temporal characteristics of the minimum rest time for the safety of South Korean outdoor workers during hot summer months (June to August) are examined based on the hourly wet-bulb globe temperature (WBGT) across 27 weather stations in South Korea. The WBGT thresholds in the work-rest recommendation of the Korea Occupational Safety and Health Agency (KOSHA 2017) for the quantification of the minimum rest time are evaluated through a comparison of the given thresholds with the occurrences of occupational heat-related illness patients due to outdoor work during hot summer months in South Korea. The long-term (2009–2018) average of the hourly WBGT values during summer months shows that outdoor workers with a moderate workload are exposed to heat stress during approximately 30% of the entire daytime working hours (06:00–18:00). According to the WBGT thresholds modified from the KOSHA (2017) guidelines, the daily minimum rest time for a moderate workload noticeably increases up to 18% (11 min/h) in mid-summer (late July and early August). During mid-summer, the minimum rest time for a continuous moderate outdoor workload even increases up to 31% (18 min/h) between 12:00 and 13:00 and is regionally higher in the southwestern than in the southeastern regions of the Korean Peninsula. These results suggest that in summertime high-heat environments, a mandatory rest time must be provided according to appropriate heat management programs for the safety of workers. [ABSTRACT FROM AUTHOR]

In Talbot-Lau interferometry, the sample position yielding the highest phase sensitivity suffers from strong geometric blur. This trade-off between phase-sensitivity and spatial resolution is a fundamental challenge in such interferometric imaging applications with either neutron or conventional x-ray sources due to their relatively large beam-defining apertures or focal spots. In this study, a deep learning method is introduced to estimate a high phase-sensitive and high spatial resolution image from a trained neural network to attempt to avoid the trade-off for both high phase-sensitivity and high resolution. To realize this, the training data sets of the differential phase contrast images at a pair of sample positions, one of which is close to the phase grating and the other close to the detector, are numerically generated and are used as the inputs for the training data set of a generative adversarial network. The trained network has been applied to the real experimental data sets from a neutron grating interferometer and we have obtained improved images both in phase-sensitivity and spatial resolution. [ABSTRACT FROM AUTHOR]

Future changes in river bed were predicted under the assumption that flow velocity of past and changes in flow rate at upstream river due to construction of large-scale artificial structures downstream occur in the future. Therefore, the long-term runoff volume from the downstream part of Hosan Stream was estimated using the SSARR (Stream Synthesis and Reservoir Regulation Model). Changes in the river bed were simulated using RMA-2 and SED-2D, which are hydraulic models. As a result, it was found that the river bed variation is significantly affected by the inclusion of sediment in flood flow at upstream. A comprehensive evaluation of above results revealed that the river width has significantly affected flow rate, and the inclusion of sediment in flood flow from the upstream has a huge effect on changes in the riverbed. In this regard, there is a need to devise measures to mitigate future flood damage to artificial structures by reflecting sedimentation trends downstream before the construction of large-scale artificial structures at downstream of river. [ABSTRACT FROM AUTHOR]

We introduce the application of a symmetric Talbot-Lau neutron grating interferometer which provides a significantly extended autocorrelation length range essential for quantitative dark-field contrast imaging. The highly efficient set-up overcomes the limitation of the conventional Talbot-Lau technique to a severely limited micrometer range as well as the limitation of the other advanced dark-field imaging techniques in the nanometer regime. The novel set-up enables efficient and continuous dark-field contrast imaging providing quantitative small-angle neutron scattering information for structures in a regime from some tens of nanometers to several tens of micrometers. The quantitative analysis enabled in and by such an extended range is demonstrated through application to reference sample systems of the diluted polystyrene particle in aqueous solutions. Here we additionally demonstrate and successfully discuss the correction for incoherent scattering. This correction results to be necessary to achieve meaningful quantitative structural results. Furthermore, we present the measurements, data modelling and analysis of the two distinct kinds of cohesive powders enabled by the novel approach, revealing the significant structural differences of their fractal nature. [ABSTRACT FROM AUTHOR]

This study assessed the potential impact of heat stress on labor productivity in South Korea; as such, stress is expected to increase due to climate change. To quantify the future loss of labor productivity, we used the relationship between the wet-bulb globe temperature and work-rest cycles with representative concentration pathways (RCPs) 4.5 and 8.5 as the climate change scenarios. If only climate factors are considered, then future labor productivity is expected to decline in most regions from the middle of the twenty-first century onwards (2041-2070). From the late twenty-first century onwards, the productivity of heavy outdoor work could decline by 26.1% from current levels under the RCP 8.5 climate scenario. Further analysis showed that regional differences in labor characteristics and the working population had noteworthy impacts on future labor productivity losses. The heat stress caused by climate change thus has a potentially substantial negative impact on outdoor labor productivity in South Korea. [ABSTRACT FROM AUTHOR]

Introduction and hypothesis: Randomized controlled trials (RCTs) provide the best quality clinical evidence. The aim of this study was to assess the quality of RCTs published by the International Urogynecology Journal (IUJ) in 2007-2016.Methods: RCTs in original articles were extracted from PubMed and IUJ homepage. Change in RCT quality over time was assessed with Jadad and van Tulder scales and Cochrane Collaboration’s risk of bias tool (CCRBT). Jadad scores of 3-5 or van Tulder scores of >5 indicated high-quality RCTs. The effect on RCT quality of including funding source and institutional review board (IRB) approval statements and describing the intervention was assessed. In addition, changes in RCT topics over time were assessed.Results: Annual RCT frequencies did not change significantly (6.7-15.7%): 36.1% and 25.7% described blinding and allocation concealment, respectively. Both tended to increase between 2013 and 2016, particularly 2013 and 2014. Funding statement inclusion (39.1% overall) and intervention description (78.2% overall) tended to increase steadily. IRB statement inclusion (60.4% overall) increased significantly (p < 0.01). Jadad scores and van Tulder rose significantly until 2014 (p < 0.01). Frequencies of high-quality RCTs tended to rise. CCRBT indicated that RCTs with a low risk of bias tended to increase until 2014. However, from 2015, Jadad scores, van Tulder, and CCRBT the low risk tended to decreased. RCTs with funding and IRB approval statements had higher Jadad and van Tulder scores than unfunded RCTs (p < 0.01 and p < 0.01, respectively). Intervention description did not associate with better quality.Conclusions: RCT quality improved over time, but a dip in quality was observed in 2015-2016 because of decreased blinding and allocation concealment. [ABSTRACT FROM AUTHOR]

We derive the isogeometric configuration sensitivity of the Mindlin plates by using the material derivative and adjoint approaches. This is utilized in the shape design optimization that includes a variation of design components in its shape and orientation. By the isogeometric approach, the NURBS basis function in CAD system is directly utilized in the response analysis, which enables the seamless incorporation of higher continuity and exact geometry such as curvature and normal vector into the computational framework. The impact of exact curvature in the bending problem of Mindlin plates on the configuration design sensitivity is demonstrated through numerical examples. The obtained design sensitivity is further utilized in the shape design optimization of built-up structures. Due to the non-interpolatory property of the NURBS basis functions, a mismatch of patches in the built-up structures could occur during the isogeometric design optimization, which can be easily resolved using transformed basis functions. [ABSTRACT FROM AUTHOR]

Purpose: To evaluate the clinical characteristics of patients with maximal urine flow rate ( Qmax) ≥ 25 ml/s complaining of lower urinary tract symptoms (LUTS), using propensity score-matching analysis to compare with the control group. Methods: Medical records from a prospectively maintained database for first visit male patients with LUTS/benign prostatic hyperplasia between 2010 and 2012 were used to select 818 patients. Of these patients, 68 men with Qmax ≥ 25 ml/s were defined as the supervoider group, and 68 patients were selected for the control group using propensity scores, which were calculated for each patient using multivariable logistic regression model based on the following covariates: age, prostate volume, voided urine volume, and post-voided residual volume. International Prostate Symptom Score (IPSS), quality of life score, and Overactive Bladder Symptom Score (OABSS) were also analyzed. Results: Mean Qmax was 30.82 ± 5.13 in supervoiders and 15.95 ± 4.88 ml/s in controls ( p < 0.001). There were statistical differences in IPSS between supervoiders and controls (12.63 ± 5.81 vs. 16.13 ± 6.90; p = 0.002). Although the IPSS voiding symptom sub-score in supervoiders was lower than controls (5.09 ± 3.35 vs. 7.40 ± 4.00; p < 0.001), there were no significant differences in storage symptom and post-micturitional symptom sub-scores. In OABSS and subdomain scores for frequency, nocturia, and urgency, there were no significant differences between the groups. However, the urge incontinence subdomain score was significantly higher in supervoiders versus controls (0.69 ± 1.26 vs. 0.18 ± 0.52; p = 0.003). Conclusions: Supervoiders experience comparable levels of storage and post-micturition symptoms, but display more severe urge incontinence despite milder voiding symptoms and better uroflowmetric measurements than propensity score-matched controls. [ABSTRACT FROM AUTHOR]

Objective: To compare patient-reported outcomes (PROs) with objective outcomes after shock wave lithotripsy (SWL) and ureteroscopic surgery (URS) for ureteral calculi (UC). Methods: We prospectively evaluated 160 consecutive patients who underwent SWL ( n = 65) or URS ( n = 95) for a single radiopaque UC ranging from 4 to 15 mm. For patients who underwent URS, a 6-Fr double-J stent was routinely placed for 2 weeks after surgery. To examine PRO, we used a self-administered nonvalidated questionnaire evaluating overall satisfaction and PRO in four domains (pain, hematuria, voiding symptom, and time to return to routine activity) and willingness to undergo the treatment procedure again. Propensity-score matching analysis was performed to adjust for potential confounding by discrepancy of pretreatment parameters between groups. Stone-free rates (SFRs) and complications were also compared. Results: SFRs after the first, second, and third sessions of SWL were 61.5, 81.0, and 93.5 %, respectively. SFR after URS was 100 %, which was significantly better than SFRs for third-session SWL ( p = 0.023). Complications were comparable. By propensity-score matching analysis, overall satisfaction was similar between groups, whereas PRO for voiding symptom and time to return to routine activity were significantly better in the SWL group (all p < 0.05). The two groups were not different in willingness to undergo the same procedure again. Conclusions: Despite significantly higher SFR after URS for UC, overall patient satisfaction was comparable after SWL and URS, meanwhile PRO of the SWL group was better than URS for voiding symptom and time to return to routine activity. In addition of objective treatment outcomes, PROs should be considered in counseling treatment methods for UC. [ABSTRACT FROM AUTHOR]

In this paper, we present clear and formal definitions of ranking factors that should be concerned in opinion retrieval and propose a new opinion retrieval model which simultaneously combines the factors from the generative modeling perspective. The proposed model formally unifies relevance-based ranking with subjectivity detection at the document level by taking multiple ranking factors into consideration: topical relevance, subjectivity strength, and opinion-topic relatedness. The topical relevance measures how strongly a document relates to a given topic, and the subjectivity strength indicates the likelihood that the document contains subjective information. The opinion-topic relatedness reflects whether the subjective information is expressed with respect to the topic of interest. We also present the universality of our model by introducing the model's derivations that represent other existing opinion retrieval approaches. Experimental results on a large-scale blog retrieval test collection demonstrate that not only are the individual ranking factors necessary in opinion retrieval but they cooperate advantageously to produce a better document ranking when used together. The retrieval performance of the proposed model is comparable to that of previous systems in the literature. [ABSTRACT FROM AUTHOR]

An amendment to this paper has been published and can be accessed via a link at the top of the paper. [ABSTRACT FROM AUTHOR]