Objective
To develop and test computer software to detect, quantify, and monitor progression of pneumonia associated with COVID-19 using chest CT scans.
Methods
One hundred twenty chest CT scans from ...subjects with lung infiltrates were used for training deep learning algorithms to segment lung regions and vessels. Seventy-two serial scans from 24 COVID-19 subjects were used to develop and test algorithms to detect and quantify the presence and progression of infiltrates associated with COVID-19. The algorithm included (1) automated lung boundary and vessel segmentation, (2) registration of the lung boundary between serial scans, (3) computerized identification of the pneumonitis regions, and (4) assessment of disease progression. Agreement between radiologist manually delineated regions and computer-detected regions was assessed using the Dice coefficient. Serial scans were registered and used to generate a heatmap visualizing the change between scans. Two radiologists, using a five-point Likert scale, subjectively rated heatmap accuracy in representing progression.
Results
There was strong agreement between computer detection and the manual delineation of pneumonic regions with a Dice coefficient of 81% (CI 76–86%). In detecting large pneumonia regions (> 200 mm
3
), the algorithm had a sensitivity of 95% (CI 94–97%) and specificity of 84% (CI 81–86%). Radiologists rated 95% (CI 72 to 99) of heatmaps at least “acceptable” for representing disease progression.
Conclusion
The preliminary results suggested the feasibility of using computer software to detect and quantify pneumonic regions associated with COVID-19 and to generate heatmaps that can be used to visualize and assess progression.
Key Points
• Both computer vision and deep learning technology were used to develop computer software to quantify the presence and progression of pneumonia associated with COVID-19 depicted on CT images.
• The computer software was tested using both quantitative experiments and subjective assessment.
• The computer software has the potential to assist in the detection of the pneumonic regions, monitor disease progression, and assess treatment efficacy related to COVID-19.
Background and Aim
Controlled attenuation parameter (CAP) is a novel ultrasound‐based elastography method for detection of steatosis severity. This meta‐analysis aimed to assess the performance of ...CAP.
Methods
PubMed, the Cochrane Library, and the Web of Knowledge were searched to find studies, published in English, relating to accuracy evaluations of CAP for detecting stage 1 (S1), stage 2 (S2), or stage 3 (S3) hepatic steatosis which was diagnosed by liver biopsy. Sensitivities, specificities, and hierarchical summary receiver operating characteristic (HSROC) curves were used to examine CAP performance. The clinical utility of CAP was also evaluated.
Results
Nine studies, with 11 cohorts were analyzed. The summary sensitivities and specificities values were 0.78 (95% confidence interval CI, 0.69–0.84) and 0.79 (95% CI, 0.68–0.86) for ≥ S1, 0.85 (95% CI, 0.74–0.92) and 0.79 (95% CI, 0.71–0.85) for ≥ S2, and 0.83 (95% CI, 0.76–0.89) and 0.79 (95% CI, 0.68–0.87) for ≥ S3. The HSROCs were 0.85 (95% CI, 0.81–88) for ≥ S1, 0.88 (95% CI, 0.85–0.91) for ≥ S2, and 0.87 (95% CI, 0.84–0.90) for ≥ S3. Following a “positive” measurement (over the threshold value) for ≥ S1, ≥ S2, and ≥ S3, the corresponding post‐test probabilities for the presence of steatosis (pretest probability was 50%) were 78%, 80% and 80%, respectively; if the values were below these thresholds (“negative” results), the post‐test probabilities were 22%, 16%, and 17%, respectively.
Conclusions
CAP has good sensitivity and specificity for detecting hepatic steatosis; however, based on a meta‐analysis, CAP was limited in their accuracy of steatosis, which precluded widespread use in clinical practice.
We present a detailed study of near-IR selected galaxies in a protocluster field at z = 3.13. Protocluster galaxies are selected using the available mutliwavelength data with the photometric ...redshifts (photo-z) at 2.9 < z < 3.3, reaching a mass completeness of . Diverse types of galaxies have been found in the field, including normal star-forming galaxies, quiescent galaxies, and dusty star-forming galaxies. The photo-z galaxies form two large overdense structures in the field, largely overlapping with the previously identified galaxy overdensities traced by Ly emitters (LAEs) and Lyman break galaxies, respectively. The northern overdensity consists of a large fraction of old and/or dusty galaxy populations, while the southern one is mainly composed of normal star-forming galaxies that are spatially correlated with the LAEs. This agrees with our previous study arguing the spatial offset of different galaxy overdensities may be due to halo assembly bias. Given the large end-to-end sizes of the two overdensities, one possibility is that they will form into a supercluster by the present day. We also find strong evidence that the star formation activities of the galaxies in the overdense protocluster regions are enhanced in comparison to their field counterparts, which suggests an accelerated mass assembly in this protocluster.
A metal‐free approach to meta‐substituted phenols from cyclohex‐2‐enone via catalytic oxidative aromatization has been developed. The transformations are initiated with a catalytic amount of ...molecular iodine as the direct oxidant, while dimethyl sulfoxide is employed as the terminal oxidant. This practical approach is capable of avoiding the use of metal promoters and costly reagents, the lengthy synthesis, and overoxidation of products, and thus facilitates the efficient construction of meta‐substituted phenol derivatives from inexpensive commercial chemicals under mild conditions. The synthetic utility of this approach is evident in the de novo syntheses of two bioactive molecules with good total yields, in which easily available chemicals were employed, protective groups were not utilized, and no unwanted carbon atoms were removed in each step.
On January 3, 2019, Chang'E-4 (CE-4) probe successfully achieved soft landing on the farside of the Moon. A large number of small craters in the landing area can be found in the high-resolution ...remote sensing images. These small craters played a vital role in the evolution of lunar regolith because of the overturning and mixing of lunar surface material through excavating and ejecting during impact processes. However, the research of the gardening process by small craters and the evolution of farside lunar regolith are still insufficient. This research aims to make quantitative analysis to the evolution of the lunar regolith from regional small impacts and apply them in the CE-4 landing area. Firstly, the processes of excavation and ejection of a single small impact on the lunar surface are analyzed, during which the formation and distribution of lunar regolith are numerically modeled. Then, based on the remote sensing observation and the analysis of regional impact flux, a group of impact events with resulting lunar regolith are modeled by Monte Carlo method. Thirdly, the above analysis is applied in the CE-4 landing area, and the thickness, grain size distribution, and overturning times of the lunar regolith are calculated. Finally, the influencing factors are discussed and evolution process of lunar regolith is summarized. The results indicate that the formation of lunar regolith is controlled by larger impact events, while the surficial overturning and mixing of lunar regolith are mainly caused by smaller impact events. In addition, the lunar regolith is mostly formed in the earlier times because of the high impact flux at that time. For example, the absolute model age of the CE-4 landing area is about 3.5 Ga, while the lunar regolith had mostly been formed before 3.0 Ga and changed slowly afterwards. Our model beyond the observational capability of the Yutu-2's lunar penetrating radar (LPR), and the results can contribute to better understanding of the regional lunar regolith formation and evolution.
•Lunar regolith evolution is quantitatively analyzed with the proposed EMSC.•Lunar regolith formation is mostly controlled by larger impact events.•Lunar regolith in CE-4 landing area is mainly formed before 3.0 Ga.
Considering topography conditions, economic factors and driving safety, in real traffic, a road may be built as curved road. Traffic flow on curved road is different from the one on straight road. ...And it is worth to investigate the influencing mechanism of traffic flow on curved road. In order to investigate traffic flow on curved road analytically, in this paper, an extended one-dimensional lattice hydrodynamic model for traffic flow on curved road is proposed. The stability condition is obtained by the use of linear stability analysis. It is shown that the stability of traffic flow varies with the radian, friction coefficient and curvature radius of curved road. The Burgers, Korteweg–de Vries and modified Korteweg–de Vries equations are derived to describe the nonlinear density waves in the stable, metastable and unstable regions, respectively. The simulations are given to verify the analytical results. The results, which obtained from the theoretical analysis and numerical simulations, show that traffic flow may be affected by the angle going into curved road, the increment of angle, friction coefficient and curvature radius of curved road. And the maximal theoretical flux and velocity of traffic flow are influenced by the above factors as well.
•A statistically RVE consisting of a number of crystal grains is applied.•The RVE is subjected to repeated symmetric tensile-compressive loading.•The inhomogeneous strain fields are statistically ...analyzed.•Three criteria are proposed for predicting LCF failure of a metal.•A family of curves for fatigue lives can be predicted by varying the critical values.
The fatigue-life of a polycrystalline superalloy under symmetrical cyclic strain controlled loading at a temperature of 650°C is investigated by numerical simulations on the micro-level, focusing on the inhomogeneous evolution of plastic deformation in a polycrystalline aggregate. A methodology (Zhang et al., 2011, 2013) to predict the low-cycle fatigue life by micro-level simulations along with statistical analysis is applied following the steps: (1) A statistically representative volume element (RVE) consisting of a number of crystal grains is constructed by Voronoi tessellation. Stresses and plastic strains are calculated by a crystal plasticity model including nonlinear kinematic hardening. (2) The RVE is subjected to repeated symmetric tensile-compressive loading. (3) The inhomogeneous stress and strain fields are statistically analyzed during the load cycles. (4) Failure by LCF is strain controlled and occurs if either of the quantities, standard deviation of longitudinal strain in tensile direction, maximum or statistical average of first principal strains in the RVE at the tension peak of cyclic loading reaches a respective critical value. (5) Using the present methodology, a family of failure curves for fatigue lives under different strain amplitudes can be predicted by varying the critical values. Finally, appropriate critical values can be identified by a respective cyclic experiment with only one strain amplitude.
G-quadruplexes are specialized secondary structures in nucleic acids that possess significant conformational polymorphisms. The precise G-quadruplex conformations in vivo and their relevance to ...biological functions remain controversial and unclear, especially for telomeric G-quadruplexes. Here, we report a novel single-chain variable fragment (scFv) antibody, D1, with high binding selectivity for parallel G-quadruplexes in vitro and in vivo. Genome-wide chromatin immunoprecipitation using D1 and deep-sequencing revealed the consensus sequence for parallel G-quadruplex formation, which is characterized by G-rich sequence with a short loop size (<3 nt). By using D1, telomeric parallel G-quadruplex was identified and its formation was regulated by small molecular ligands targeting and telomere replication. Together, parallel G-quadruplex specific antibody D1 was found to be a valuable tool for determination of G-quadruplex and its conformation, which will prompt further studies on the structure of G-quadruplex and its biological implication in vivo.
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•A new antibody with parallel G-quadruplex specific recognition•Consensus sequence for parallel G-quadruplex formation on the human genome•Identification of parallel G-quadruplex formation at telomeres•Modulation of telomeric parallel G-quadruplex formation in human cell
G-quadruplex conformation in vivo is difficult to assay, especially for telomeric G-quadruplexes. Liu et al. demonstrate the parallel G-quadruplex consensus sequence on the genome and identify the regulated formation of parallel quadruplex at telomeres by using a new antibody.
In this paper, an extended traffic flow model on a single-lane gradient highway is proposed with the consideration of the relative velocity. The stability condition is obtained by the use of linear ...stability analysis. It is shown that the stability of traffic flow on the gradient varies with the slope and the coefficient of the relative velocity: when the slope is constant, the stable regions increase with the increase of the coefficient of the relative velocity; when the coefficient of the relative velocity is constant, the stable regions increase with the decrease of the slope in downhill and increase with the increase of the slope in uphill. The Burgers, Korteweg-de Vries, and modified Korteweg-de Vries equations are derived to describe the triangular shock waves, soliton waves, and kink-antikink waves in the stable, metastable, and unstable region, respectively. The numerical simulation shows a good agreement with the analytical result, which shows that the traffic congestion can be suppressed by introducing the relative velocity.
The method of aggregating a large number of constraints into one or few constraints has been successfully applied to wing structural design using gradient-based local optimization. However, numerical ...difficulties may occur in the case that the local curvatures of the aggregated constraint become extremely large and then ill-conditioned Hessian matrix may be yielded. This paper aims to test different methods of constraint aggregation within the framework of a gradient-free optimization, which makes use of cheap-to-evaluate surrogate models to find the global optimum. Three constraint aggregation approaches are investigated: the maximum constraint approach, the constant parameter Kreisselmeier-Steinhauser (KS) function, and the adaptive KS function. We also explore methods of aggregating constraints over the entire structure and within sub-domains. Examples of structural optimization and aero-structural optimization for a transport aircraft wing are employed and the results show that (1) the KS function with a larger constant parameter
ρ
can lead to better optimization results than the adaptive method, as the active constraints are approximated more accurately; (2) lumping the constraints within sub-domains instead of all together can improve the accuracy of the aggregated constraint and therefore helps find a better design. Finally, it is concluded from current test cases that the most efficient way of handling large-scale constraints for wing surrogate-based optimization is to aggregate constraints within sub-domains and with a relatively large constant parameter.
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