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3D digital subtraction angiography (DSA) reconstruction from rotational 2D projection X-ray angiography is an important basis for diagnosis and treatment of intracranial aneurysms (IAs). The gold standard requires approximately 133 different projection views for 3D reconstruction. A method to significantly reduce the radiation dosage while ensuring the reconstruction quality is yet to be developed. We propose a self-supervised learning method to realize 3D-DSA reconstruction using ultra-sparse 2D projections. 202 cases (100 from one hospital for training and testing, 102 from two other hospitals for external validation) suspected to be suffering from IAs were conducted to analyze the reconstructed images. Two radiologists scored the reconstructed images from internal and external datasets using eight projections and identified all 82 lesions with high diagnostic confidence. The radiation dosages are approximately 1/16.7 compared with the gold standard method. Our proposed method can help develop a revolutionary 3D-DSA reconstruction method for use in clinic.

Background and Objectives: To investigate whether coronavirus disease 2019 (COVID-19) survivors who had different disease severities have different levels of pulmonary sequelae at 3 months post-discharge.Methods: COVID-19 patients discharged from four hospitals 3 months previously, recovered asymptomatic patients from an isolation hotel, and uninfected healthy controls (HCs) from the community were prospectively recruited. Participants were recruited at Wuhan Union Hospital and underwent examinations, including quality-of-life evaluation (St. George Respiratory Questionnaire [SGRQ]), laboratory examination, chest computed tomography (CT) imaging, and pulmonary function tests.Results: A total of 216 participants were recruited, including 95 patients who had recovered from severe/critical COVID-19 (SPs), 51 who had recovered from mild/moderate disease (MPs), 28 who had recovered from asymptomatic disease (APs), and 42 HCs. In total, 154 out of 174 (88.5%) recovered COVID-19 patients tested positive for serum SARS-COV-2 IgG, but only 19 (10.9%) were still positive for IgM. The SGRQ scores were highest in the SPs, while APs had slightly higher SGRQ scores than those of HCs; 85.1% of SPs and 68.0% of MPs still had residual CT abnormalities, mainly ground-glass opacity (GGO) followed by strip-like fibrosis at 3 months after discharge, but the pneumonic lesions were largely absorbed in the recovered SPs or MPs relative to findings in the acute phase. Pulmonary function showed that the frequency of lung diffusion capacity for carbon monoxide abnormalities were comparable in SPs and MPs (47.1 vs. 41.7%), while abnormal total lung capacity (TLC) and residual volume (RV) were more frequent in SPs than in MPs (TLC, 18.8 vs. 8.3%; RV, 11.8 vs. 0%).Conclusions: Pulmonary abnormalities remained after recovery from COVID-19 and were more frequent and conspicuous in SPs at 3 months after discharge.

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The $\beta-\text{Ga}_{2}\mathrm{O}_{3}$ Schottky barrier diode (SBD) is fabricated and actualized a breakdown voltage of 472 V. A SPICE model for $\beta-\text{Ga}_{2}\mathrm{O}_{3}$ Sbd is derived from experimental results and applied to DC-DC converter circuit simulation. Then the $\beta-\text{Ga}_{2}\mathrm{O}_{3}$ SBD is implemented in a DC-DC converter circuit and acquired the conversion efficiency of 94.8%, indicating the great potential of Ga 2 O 3 -based devices and circuits.

BACKGROUND: This study aimed to explore the coordinated and independent actions of lung lobes during respiration using quantitative computed tomography (CT) in order to increase our in vivo understanding of pulmonary anatomy. METHODS: Cases for whom test results showed normal pulmonary function tests (PFTs) results, and normal paired inspiratory-expiratory chest CT findings, as assessed by 2 radiologists, were retrospectively included in this study. From the chest CT results, we measured quantitative indices of lung volume (LV) and mean lung density (MLD) for the total lung (TL), left lung (LL), right lung (RL), and 5 lobes in inspiratory and expiratory phases. The differences of these measures between bilateral lungs and among the lobes were evaluated to study whether they were consistent or different during respiration. RESULTS: A total of 70 cases were included {median age of 49.5 [interquartile range (IQR), 38.0 to 60.3] years; 32 males; 38 females}. Overall, the inspiratory and expiratory volumes of the LL were smaller than those of the RL (both P0.999; expiration: P=0.975). In addition, the PMADs between the right middle lobe (RML) and other lobes were significantly larger than the PMAD between other pairs of lobes in both inspiration and expiration. Beyond that, the expiratory MLD of RML [−789.6 (IQR, −814 to −762.05) HU] was the lowest among the 5 lobes. CONCLUSIONS: We found that the LL assumes a higher workload during ventilation than it does during respiration. The 5 normal lobes were non-synchronous during respiration and contributed differently to ventilation. The bilateral lower lobes showed similarities and had a high-ventilation function, while and the LV and MLD of the RML showed the least changes within a respiration cycle.

Objective To compare the 5-year outcomes of acute versus subacute thoracic endovascular aortic repair (TEVAR) in patients with uncomplicated acute type B aortic dissection (ATBAD). Methods Between March 2008 and September 2018, 238 consecutive patients with uncomplicated ATBAD underwent TEVAR in the acute or subacute phase and were analyzed retrospectively. The primary end points were all-cause death and aortic-related death. The secondary end point was a composite of the outcomes of death from any cause, rupture, new dissection, retrograde type A aortic dissection, endoleak, and late reintervention. Inverse probability treatment weighting was used to balance baseline characteristics. Weight-adjusted Kaplan-Meier estimate with landmark analysis and weighted Cox model were performed to assess time-to-event outcomes. Results In the inverse probability treatment weighting-adjusted population, the 30-day mortality was 1.5% in the acute TEVAR group and 0% in the subacute TEVAR group (P = .24). The incidence of 30-day adverse events occurred in 16.8% and 6.9% patients in the acute TEVAR and subacute TEVAR groups, respectively (P = .13). At 5 years, there was no statistically significant difference in all-cause death (hazard ratio [HR], 1.50; 95% confidence interval [CI], 0.59-3.81; P = .39) and aortic-related death (HR, 1.11; 95% CI, 0.34-3.60; P = .86) between the two groups. The composite outcomes occurred in 30 patients (23.0%) in the acute TEVAR group and 18 patients (22.3%) in the subacute TEVAR group, respectively (HR, 0.67; 95% CI, 0.36-1.25; P = .20). However, a landmark analysis of the composite outcomes indicated that there was a significant interaction between treatment effect and time (Pinteraction = .01), with a significantly higher incidence of the composite outcomes in the acute TEVAR group compared with the subacute TEVAR group within 1 year (HR, 0.25; 95% CI, 0.08-0.79; P = .02), and a comparable rate between 1 and 5 years (HR, 1.25; 95% CI, 0.56-2.76; P = .59). Conclusions At the 5-year follow-up, no significant differences exist in the all-cause death and aortic-related death between acute and subacute TEVAR. However, acute TEVAR is associated with an increased rate of severe complications within 1 year, which suggests that performing TEVAR in the subacute phase of ATBAD may be the preferable option.

BackgroundChest computed tomography (CT) has been widely used to assess pulmonary involvement in COVID-19. We aimed to investigate the correlation between chest CT and clinical features in COVID-19 suspected patients with or without fever.MethodsWe retrospectively enrolled 211 COVID-19 suspected patients who underwent both chest CT and reverse transcription polymerase chain reaction in Wuhan, China. The performance of CT in patients with relevant onset of symptoms, with fever (n = 141) and without fever (n = 70), was assessed respectively.ResultsThe sensitivity of CT for COVID-19 was 97.3%, with area under the curve (AUC) of 0.71 (95% confidence interval [CI], 0.66–0.76). There were 141 suspected patients with fever and 70 without fever. In the fever group, 4 variables were screened to establish the basic model: age, monocyte, red blood cell, and hypertension. The AUC of the basic model was 0.72 (95% CI, 0.63–0.81), while the AUC of the CT-aided model was 0.77 (95% CI, 0.68–0.85), a significant difference (P < .05). In the nonfever group, only dry cough was screened out to establish the basic model. The AUC was 0.76 (95% CI, 0.64–0.88), which was not significantly different than the CT-aided model (P = .08).ConclusionsChest CT has a high sensitivity in patients with COVID-19, and it can improve diagnostic accuracy for COVID-19 suspected patients with fever during the initial screen, whereas its value for nonfever patients remains questionable.

This study aims to investigate radiological and clinical characteristics of suspected COVID-19 patients with negative RT-PCR testing. 22 suspected COVID-19 patients with 2-5 negative RT-PCR testing were enrolled. The most common symptoms at onset included fever (18[81.8%] patients), fatigue (16[72.7%]) and cough (12[54.5%]). 20(90.9%) patients were with normal or decreased Leukocyte count, 17 (77.3%) with decreased Lymphocyte count, 16 (72.7%) and 18 (81.8%) with increased level of C-reactive protein and D-dimers, respectively. Ground-glass opacity (GGO) (22[100]), reticular/interlobular septal thickening (11 [50%]) and consolidation (14 [63.6%)) with predominantly bilateral and peripheral distribution were typical findings at initial CT scan. The CT score of right lower lobe was significantly higher than right upper lobe (P=0.042). The total CT scores of group 2, 3, 4 (2nd week, 3rd week, 4th week and after) were significantly higher than group 1 (1st week) (P＜0.01,for all). After rapid progression at first week, the most extensive pulmonary involvement emerged at second week after symptom onset, then the involvement gradually decreased. Given the clinical symptoms, laboratory results and typical radiological manifestations, even suspected COVID-19 patients with multiple negative RT-PCR testing deserve great concern for active management.

The outstanding thermal properties, mechanical properties and large optical bandgap of hexagonal boron nitride (h-BN) make it very attractive for various applications in ultrathin 2D microelectronics. However, the synthesis of large lateral size and uniform h-BN thin films with a high breakdown strength still remains a great challenge. Here, we comprehensively investigated the effect of growth conditions on the thickness of h-BN films via low pressure chemical vapor deposition (LPCVD). By optimizing the LPCVD growth parameters with electropolished Cu foils as the deposition substrates and developing customized “enclosure” quartz-boat reactors, we achieved thickness-tunable (1.50–10.30 nm) growth of h-BN thin films with a smooth surface (RMS roughness is 0.26 nm) and an ultra-large area (1.0 cm × 1.0 cm), meanwhile, the as-grown h-BN films exhibited an ultra-high breakdown strength of ∼10.0 MV cm−1, which is highly promising for the development of electrically reliable 2D microelectronic devices with an ultrathin feature.

Due to the lack of commercialized high voltage DC circuit breaker (DCCB), the protection of voltage source converter-based (VSC) multi-terminal HVDC (MTDC) grid is still a main obstacle hinders the development of MTDC grid. In this paper, the DC grid protection and post-fault restoration schemes using AC circuit breakers (ACCBs) are proposed. The contributions of this paper are: 1) analyses the post-fault restoration process if ACCB is used for DC grid protection; 2) analyses the difference between starting a MTDC grid from a zero-state and post-fault state; 3) DC voltage slope control is used to limit the overvoltage and overcurrent during the restart-up process. The proposed protection and restart-up control scheme will be tested in an offshore wind farm (OWF) integrated 4-terminal DC grid established in PSCAD/EMTDC. The simulation results show the effectiveness and good dynamic performance of the proposed scheme. The voltage oscillation and current surges are mitigated largely during the restart-process.

The decrease in electronic device size necessitates greater understanding of gas breakdown and electron emission at microscale to optimize performance. While traditional breakdown theory using Paschen’s law (PL), driven by Townsend avalanche, fails for gap distance d $$\lesssim $$ ≲ 15 μm, recent studies have derived analytic equations for breakdown voltage when field emission and Townsend avalanche drive breakdown. This study derives a new analytic equation that predicts breakdown voltage VB within 4% of the exact numerical results of a previously derived theory and new experimental results at subatmospheric pressure for gap distances from 1–25 μm. At atmospheric pressure, VB transitions to PL near the product of pressure and gap distance, pd, corresponding to the Paschen minimum; at lower pressures, the transition to PL occurs to the left of the minimum. We further show that the work function plays a major role in determining which side of the Paschen minimum VB transitions to PL as pressure approaches atmospheric pressure while field enhancement and the secondary emission coefficient play smaller roles. These results indicate that appropriate combinations of these parameters cause VB to transition to PL to the left of the Paschen minimum, which would yield an extended plateau similar to some microscale gas breakdown experimental observations.

In this paper, the short-wave signal propagation modeling, short-wave electromagnetic environment simulation modeling, short-wave electromagnetic environment level evaluation modeling, simulation modeling of receiving antenna commonly used in short wave and other contents are studied in depth, in terms of short-wave electromagnetic environment and antenna simulation simulation. A more complete propagation model of short-wave signal, simulation model of short-wave electromagnetic environment, evaluation model of short-wave electromagnetic environment level and simulation model of receiving antenna commonly used in short-wave are established. Finally, the effectiveness of each model is verified by repeated comparative tests and experiments.

The state estimation problem of targets detected by infrared/laser composite detection system with different sampling rates was studied in this paper. An effective state estimation algorithm based on data fusion is presented. Because sampling rate of infrared detection system is much higher than that of the laser detection system, the theory of multi-scale analysis is used to establish multi-scale model in this algorithm. At the fine scale, angle information provided by infrared detection system is used to estimate the target state through the unscented Kalman filter. It makes full use of the high frequency characteristic of infrared detection system to improve target state estimation accuracy. At the coarse scale, due to the sampling ratio of infrared and laser detection systems is an integer multiple, the angle information can be fused directly with the distance information of laser detection system to determine the target location. The fused information is served as observation, while the converted measurement Kalman filter (CMKF) is used to estimate the target state, which greatly reduces the complexity of filtering process and gets the optimal fusion estimation. The simulation results of tracking a target in 3-D space by infrared and laser detection systems demonstrate that the proposed algorithm in this paper is efficient and can obtain better performance than traditional algorithm.

In order to coordinate the impact of the integration of electric vehicles and wind power on the economic dispatch of power systems, a multi-objective dispatch model for the environmental economy of wind farms with PHEVs connected to the grid was constructed. The uncertain factors of wind power generation and load will increase the difficulty of dispatching. The fuzzy theory will be used to realize the fuzzy modelling of the coordinated connection of wind power and electric vehicles. The satisfaction index will be used to transform the multi-objective problems of deterministic environment and economy into single For the objective optimization problem, based on the improvement of the traditional particle swarm optimization algorithm using linear descent search ideas and the particle information sharing method considering boundary constraints, the improved PSO algorithm is used to solve the proposed dynamic environment and economic dispatch model. From the grid operation and vehicle owners from the perspective of demand, the constraints of the system’s rotation reserve and the daily travel of the owner are considered. The comparison and analysis of the simulation of algorithms and calculation examples and multiple scheduling schemes in different scenarios verify the rationality of the model and the superiority of the improved PSO algorithm for solving such dynamic scheduling problems.

Protein-protein interaction plays a pivotal role in biological metabolism. It directs many cellular processes like signal transduction, DNA replication and RNA splicing, etc. Identification of protein-protein interaction sites is important to identification of protein functions, improvement of protein-protein docking and rational drug design. Experimental methods to identify protein-protein interaction sites are always time-consuming and costly, which calls for computational methods to be applied in this area. The research work focuses on three parts: (1) We have built a Protein-Protein Interface Database (PPIDB) which extracted 71, 486 protein-protein interfaces from experimentally determined protein complex structures in the current version of Protein Data Bank. It facilitates construction of well-characterized datasets of protein-protein interface residues for computational analyses. The database is accessible through the Web Interface http://ppidb.cs.iastate.edu and a set of Web services. (2) We have made a comprehensive analysis of protein-protein dimeric interfaces, which consists of thirteen physic-chemical properties. The results disclose that interface residues have side chains pointing inward; interfaces are rougher, tend to be flat, moderately convex or concave and protrude more relative to non-interface surface residues; interface residues tend to be surrounded by hydrophobic neighbors. (3) We have developed NB PPIPS, a Naive Bayes method to predict protein-protein interaction sites on protein surfaces. Trained over a non-redundant data set consisting of 2, 383 proteins and fed with sequence, evolutionary and structural properties, NB PPIPS achieves 60.7% recall and 34.6% precision in 10 fold cross-validation, which greatly improves over the baseline classifier that only utilizes protein sequence information. Attempts are made to apply the NB PPIPS in a two stage prediction of protein-protein interfaces when only protein sequence is known. Modeled protein structures are generated via homologue modeling and fed as inputs into NB PPIPS. The results show that good predictions are obtained only for well modeled structures. NB PPIPS is implemented as an online server to facilitate its usage. It is accessible at http://watson.cs.iastate.edu/nb_ppips.

Hexagonal boron nitride (h-BN) is known as promising 2D material with a wide band-gap $( 5.2 \sim 5.9$ eV) which has high breakdown strength. To synthesize h-BN films, chemical vapor deposition (CVD) method is proved to be an effective method that allows the scaled synthesis of h-BN. In this study, we demonstrate a low pressure chemical vapor deposition (LPCVD) method to synthesize complete and uniform h-BN films. In order to obtain high crystalline h-BN films, we studied the flow rate of carrier gas and precursor sublimation temperature on the growth of h-BN films. The results indicate the flow rate of carrier gas has little influence on growth of h-BN films. Nevertheless, the lower precursor sublimation temperature contributes to lower growth rate, which makes the thickness of h-BN films is easily controlled. When the sublimation temperature is more than 100 the thickness of h-BN films is hard to control. The breakdown strength of h-BN films is higher than 9.0 MV/cm from the I-V test, which makes h-BN films ideal substrates and insulators for 2D microelectronic devices.

The electrical discharge and insulation performance at microscale have attracted much attention as the physical dimensions of electron devices are aggressively shrinking down. Hence, to prevent unwanted breakdown or utilize for producing microplasma, both require a better understanding of the physical process of breakdown across micro gaps, which cannot be explained by the classical Paschen law1. Therefore, in the present work, the discharge morphology and breakdown channels across various gap lengths have been investigated in air atmosphere, based on the home-built electro-optical measurement system2, The pulse breakdown voltages as a function of gap lengths are obtained as well as the corresponding discharge morphology.

Reservoirs are commonly recharged by groundwater that is rich in bicarbonate ions in karst regions of South China, and the recharge of this groundwater to the reservoir can affect the biogeochemical processes of carbon sedimentation at the reservoir bottom. In this study, Dalongdong Reservoir, which is mainly recharged by two subterranean streams, was investigated based on a 42-cm-thick sedimentary core and the 210Pb/137Cs dating technique and isotope analyses to understand the sedimentary history and identify the carbon sources. The 210Pb/137Cs age model showed that the sediments were accumulated over the last 60 years. The annual increase precipitation and temperature showed no obvious change compared with trends of δ13C in total organic carbon (δ13Corg), δ15N values in total nitrogen, and the carbon and nitrogen ratio (C/N). This shows that climate was not the main control of the variation in sediment factors. Based on δ13Corg, δ15N, C/N, and isotopic mixing modeling, sources of organic carbon in the sediments were derived from plankton (60.84%), soil (22.93%), waste water (14.56%), and terrestrial plants (1.67%). From 1958 to 1978, reservoir establishment and leakage affected the contribution of the four sources. The contribution of the plankton source increased from 1978 to 2015, resulting from change of water level and continued input of external nitrogen. However, because of the revegetation supplied by an economic aid project the contribution of soil showed a considerable decreasing trend from 1978 to 2002. After 2002, For "Grain for Green" project, the contribution from soil further decreased. After reservoir construction, the contribution of waste water stabilized. The contribution of terrestrial plants started increased rapidly after 2002. Karst groundwater, which contains more dissolved inorganic carbon containing lower δ13CDIC than the water sources of other lakes or reservoirs, makes the δ13Corg value of sediment more negative by phytoplankton photosynthesis in the reservoir.

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To discuss the soft palate, hard palate and mandibule for the pathogenesis and clinical treatment of patients who have obstructive sleep apnea hypopnea syndrome.There were 52 patients with OSAHS diagnosed by the PSG and 32 cases of normal healthy volunteers in our hospital. All objects were given 128 slice spiral CT scan of the upper airway. We measured the related indexes of the soft palate, hard palate and mandible, then analysed statistical differences between them and did Pearson correlation analysis with apnea hypoventilation index (AHI), average blood oxygen saturation (MSaO2) in PSG.Compared with the control group, the soft palate length [(37.93 ± 5.20)mm VS (33.52 ± 4.25)mm] and the distance between mandible with cervical vertebra [(75.00 ± 7.10)mm VS (69.93 ± 5.58)mm] increased significantly, but the distance of trailing edge of hard palate to inferior margin of slope significantly reduced [(42.57 ± 4.52)mm VS (45.80 ± 2.94)mm, P0.01] in patients with OSAHS. Each measurement associated with AHI and MSaO2 had no significant correlation (P0.05).The soft palate, hard palate and mandibular are some of the important risk factors of OSAHS, and they also have reference value for the choice of clinical treatment operation. Preoperative CT examination can offer help in the treatment of OSAHS.

Microscale gas breakdown plays a critical role in microplasma generation for numerous applications and device lifetime for miniaturized electronics. This communication extends a previous investigation of pulsed breakdown morphology [G. Meng et al., Phys. Plasmas 25, 082116 (2018)] by providing further insight into the spatio-temporal dynamics of pulsed gas breakdown for different gap distances using an in-situ electrical-optical measurement method. Time-resolved sequential images and the corresponding photon number distributions are obtained to demonstrate the dynamic evolution of the breakdown channel morphology and the ionization intensity during breakdown development. For a 15 μm gap, breakdown transitions from a spot area on both electrode surfaces to a broad discharge region comprised of filamentary main breakdown channel (∼2.00 μm) and surrounding weak ionization area due to the local field enhancement. For a 2 μm gap, it transitions from a thin channel (∼1.09 μm) to a wider and uniform channel (∼2.14 μm) because the electric field is more uniform at smaller gaps. Interestingly, the main breakdown channel width at the instant of breakdown is independent of the gap width. For the 2 μm gap, field emission dominates the initial stage of breakdown and collision ionization (α process) dominates during breakdown development, while the Townsend avalanche dominates the breakdown process for the 15 μm gap. We apply a simple asymptotic theory to quantify the relative contribution of these phenomena and predict that breakdown will follow Paschen's law for gaps larger than 17.8 μm.