PDS-MAR: a fine-grained Projection-Domain Segmentation-based Metal Artifact Reduction method for intraoperative CBCT images with guidewires

Since the invention of modern CT systems, metal artifacts have been a persistent problem. Due to increased scattering, amplified noise, and insufficient data collection, it is more difficult to suppress metal artifacts in cone-beam CT, limiting its use in human- and robot-assisted spine surgeries where metallic guidewires and screws are commonly used. In this paper, we demonstrate that conventional image-domain segmentation-based MAR methods are unable to eliminate metal artifacts for intraoperative CBCT images with guidewires. To solve this problem, we present a fine-grained projection-domain segmentation-based MAR method termed PDS-MAR, in which metal traces are augmented and segmented in the projection domain before being inpainted using triangular interpolation. In addition, a metal reconstruction phase is proposed to restore metal areas in the image domain. The digital phantom study and real CBCT data study demonstrate that the proposed algorithm achieves significantly better artifact suppression than other comparing methods and has the potential to advance the use of intraoperative CBCT imaging in clinical spine surgeries.Comment: 19 Page

Coexistence and transformation from urban industrial land to green space in decentralization of megacities: A case study of Daxing District, Beijing, China

Decentralization is essential for the sustainable socio-economic development of megacities. In the context of the decentralization of noncapital functions in Beijing, the renewal of inefficient urban industrial land (UIL) into urban green space (UGS) is an important way to improve the quality of the city. This paper analyzes the urban industrial land use efficiency (UILUE) and its urban green space suitability (UGSS) of 865 study units in Daxing District, Beijing, and combines bivariate spatial autocorrelation with cluster analysis. The results show that (1) the distribution of UIL in Daxing District is “dense in the north and sparse in the south”, and UILUE shows a spatial pattern of “high in the west and low in the east”, with a high-efficiency area of 985.85 ha, accounting for 12.06 % of the study area, and a low-efficiency area of 507.77 ha, accounting for 6.21 % of the study area. (2) Among the existing UIL, the high suitable area is 1106.46 ha, accounting for 13.57 % of the study area, and the low suitable area is 439 ha, accounting for 5.38 % of the study area. (3) Through bivariate spatial autocorrelation analysis, four types of UIL were identified, among which the low–high cluster area had the greatest potential for land conversion, with 175 study units and an area of 1335.22 ha, accounting for 16.28 % of the study area. Finally, this paper proposes recommendations for the renewal and utilization of UIL in Daxing District to provide guidance and suggestions for the decentralization of other megacities in the world

Fairness Evaluation of Landscape Justice in Urban Park Green Space: A Case Study of the Daxing Part of Yizhuang New Town, Beijing

Equitable distribution of urban park green space benefits public health and improves quality of life. From the perspective of landscape justice, this study establishes a subjective and objective comprehensive fairness evaluation method and analyzes the fairness of the spatial distribution of park green space in the Daxing part of Yizhuang New Town, Beijing and its relationship with the economic level of residents. The results show that: (1) the green space in the Daxing part of Yizhuang New Town is concentrated in the town center and distributed more sparsely in surrounding areas; (2) urban park green space is not equitable in quantity, area, disaster prevention and avoidance, or accessibility; (3) high-grade apartment complexes have higher quality of services than low-grade apartment complexes, and the number of parks, per capita park area, disaster prevention and avoidance, and park accessibility are all higher for high-grade than for low-grade apartment complexes. Medium-grade apartment complexes have a high level of green space services, and the number of parks, total area, and accessibility are 1.06, 2.58, and 1.13 times higher than those of high-grade apartment complexes, respectively. Conversely, disaster prevention and avoidance and park area per capita of medium-grade apartment complexes are lower than in high-grade apartment complexes, at 0.81 and 0.12 times, respectively. This study provides a new perspective for exploring society and landscape equity and concludes with suggestions for improving park green space public services

Creating an Immersive Virtual Reality Game Space for Multiuser, Synchronous Co-Located Collaboration: Design Considerations and Influencing Factors

The last decade has witnessed the rapid development of immersive virtual reality (IVR) and its application in various contexts. However, its application in supporting real-time virtual collaboration has been quite rare due to technical barriers and the lack of validated design principles. To address this research gap, this study designed and developed an IVR space to enable multiuser synchronous co-located collaboration to complete a fantasy game. An evaluation study (N = 95) was conducted to explore its useful design considerations and the influencing factors for collaboration experience in the game. The IVR space was enabled by the simultaneous localization and mapping (SLAM)-based inside-out tracking technique and was informed by four essential design considerations for promoting effective collaboration in IVR, namely, the role script, learning task, collaboration mechanism, and communication design. The study results revealed that students in general were satisfied with their collaboration experience in IVR, with social presence and collaboration competency as significant predictors of collective efficacy and social experience. Based on both quantitative and qualitative results, this study proposes four validated principles for designing effective IVR spaces to support synchronous co-located collaboration

Failure Analysis of Cracked P110 Repaired Tubing Used for Gas Transmission

With green and low-carbon developments in oil fields, an increasing amount of repaired oil tubing is being used as oil and gas transmission pipelines in China. However, due to differences in manufacturing standards between oil tubing and transmission pipelines, there are inevitably some issues during their use. This paper investigates a case of cracking failure in repaired oil tubing used as a gathering and transportation pipeline. The failure occurred after eight months of operation and was characterized by a circumferential crack at the male thread end of the tubing joint. To determine the root cause of the failure, a series of experiments were conducted on the oil tubing. The experiments included visual inspection, chemical composition analysis, mechanical properties testing, hardness testing, metallographic examination, and microstructure analysis. The results revealed that the thread of the cracked tubing was not tightened to the specified position; the connection between the tubing and the coupling was welded in a circumferential direction; and cracks occurred in the heat-affected zone of the weld. Chemical composition, tensile performance, and the Charpy impact of the tubing meet the requirements of API 5CT for P110 material, and no abnormalities were found in the metallographic structure. The microstructure at the weld toe of the fracture is martensite, and the hardness is 476 HV10. Based on the thermal simulation verification test, when the material of the tubing cools from 1200 °C, which is located in the coarse HAZ temperature zone, the base metal transforms into martensite with a little granular bainite, exhibiting its highest hardness value at 371 HV10, which is higher than the allowable hardness for carbon steel and indicates the material has poor weldability. The reasons for the cracking and failure of the tubing are that the P110 repaired tubing has a high carbon equivalent and poor weldability. During the welding process, martensitic structure was formed at the weld toe, and cold cracks appeared in the heat-affected zone, resulting in failure. To avoid the reoccurrence of such failure, recommendations are proposed

Metabolomic Analysis Reveals the Metabolic Diversity of Wild and Cultivated Stellaria Radix (Stellaria dichotoma L. var. lanceolata Bge.)

Stellaria Radix, called Yinchaihu in Chinese, is a traditional Chinese medicine, which is obtained from the dried roots of Stellaria dichotoma L. var. lanceolata Bge. Cultivated yinchaihu (YCH) has become a main source of production to alleviate the shortage of wild plant resources, but it is not clear whether the metabolites of YCH change with the mode of production. In this study, the contents of methanol extracts, total sterols and total flavonoids in wild and cultivated YCH are compared. The metabolites were analyzed by ultra-high performance liquid chromatography–tandem time-of-flight mass spectrometry. The content of methanol extracts of the wild and cultivated YCH all exceeded the standard content of the Chinese Pharmacopoeia. However, the contents of total sterols and total flavonoids in the wild YCH were significantly higher than those in the cultivated YCH. In total, 1586 metabolites were identified by mass spectrometry, and 97 were significantly different between the wild and cultivated sources, including β-sitosterol, quercetin derivatives as well as many newly discovered potential active components, such as trigonelline, arctiin and loganic acid. The results confirm that there is a rich diversity of metabolites in the wild and cultivated YCH, and provide a useful theoretical guidance for the evaluation of quality in the production of YCH

Metabolomic Analysis Reveals the Metabolic Diversity of Wild and Cultivated Stellaria Radix (<i>Stellaria dichotoma</i> L. var. <i>lanceolata</i> Bge.)

Stellaria Radix, called Yinchaihu in Chinese, is a traditional Chinese medicine, which is obtained from the dried roots of Stellaria dichotoma L. var. lanceolata Bge. Cultivated yinchaihu (YCH) has become a main source of production to alleviate the shortage of wild plant resources, but it is not clear whether the metabolites of YCH change with the mode of production. In this study, the contents of methanol extracts, total sterols and total flavonoids in wild and cultivated YCH are compared. The metabolites were analyzed by ultra-high performance liquid chromatography–tandem time-of-flight mass spectrometry. The content of methanol extracts of the wild and cultivated YCH all exceeded the standard content of the Chinese Pharmacopoeia. However, the contents of total sterols and total flavonoids in the wild YCH were significantly higher than those in the cultivated YCH. In total, 1586 metabolites were identified by mass spectrometry, and 97 were significantly different between the wild and cultivated sources, including β-sitosterol, quercetin derivatives as well as many newly discovered potential active components, such as trigonelline, arctiin and loganic acid. The results confirm that there is a rich diversity of metabolites in the wild and cultivated YCH, and provide a useful theoretical guidance for the evaluation of quality in the production of YCH

Isolation and Characterization of a Green-Tissue Promoter from Common Wild Rice (Oryza rufipogon Griff.)

Promoters play a very important role in the initiation and regulation of gene transcription. Green-tissue promoter is of great significance to the development of genetically modified crops. Based on RNA-seq data and RT-PCR expression analysis, this study screened a gene, OrGSE (GREEN SPECIAL EXPRESS), which is expressed specifically in green tissues. The study also isolated the promoter of the OrGSE gene (OrGSEp), and predicted many cis-acting elements, such as the CAAT-Box and TATA-Box, and light-responding elements, including circadian, G-BOX and GT1 CONSENSUS. Histochemical analysis and quantification of GUS activity in transgenic Arabidopsis thaliana plants expressing GUS under the control of OrGSEp revealed that this promoter is not only green tissue-specific, but also light-inducible. The ability of a series of 5&rsquo;-deletion fragments of OrGSEp to drive GUS expression in Arabidopsis was also evaluated. We found that the promoter region from &minus;54 to &minus;114 is critical for the promoter function, and the region from &minus;374 to &minus;114 may contain core cis-elements involved in light response. In transgenic rice expressing GUS under the control of OrGSEp, visualization and quantification of GUS activity showed that GUS was preferentially expressed in green tissues and not in endosperm. OrGSEp is a useful regulatory element for breeding pest-resistant crops