Depth estimation method of surface of micropart in microassembly space based on microscopic vision tomographic scanning images.

Three-dimensional (3D) morphology of microparts has an important influence on performance of microassembly system that mainly assembles microparts in millimetre and micron scale. Because 3D morphology of microparts cannot be accurately obtained by conventional microscopic vision system, a depth estimation method of surface of micropart in microassembly space based on microscopic vision tomographic scanning (MVTS) images is proposed in this paper. The proposed method uses the positions of pixels with the largest focus values in MVTS image to construct the isodepth contours of surface of micropart and obtains the depth values of micropart's surface at the positions of MVTS by assigning depth values to corresponding isodepth contours. The MVTS images are obtained by MVTS and pixels with the largest focus values in MVTS image are obtained by focus measurement of MVTS images of micropart in microassembly space. On these bases, 3D spatial interpolation method is applied to map depth value of space between adjacent isodepth contours and to obtain depth values of all surface of micropart. Simulation experiments are carried out to verify the proposed method by generating simulated MVTS image array from two simulation objects, and the influence parameters of the proposed method are analysed. In established experimental setup of microassembly that can realise MVTS, experimental verification for the proposed depth estimation method are carried out by using cone cavity and end jaws of microgripper. 3D morphologies of depth maps of cone cavity and end jaws of microgripper are registered with their respective CAD models using iterative nearest point registration algorithm to quantify accuracy of depth estimation. The research results show that 3D morphology of micropart can be obtained by the proposed method and has better accuracy than those by conventional shape from focus method. This method provides a new way to obtain the morphology of microparts and lays a foundation for improving the accuracy and efficiency of gripping, alignment and approaching microparts in microassembly systems.

Accuracy of Pedicle Screw Insertion Among 3 Image-Guided Navigation Systems: Systematic Review and Meta-Analysis.

BACKGROUND: Many retrospective studies of pedicle screw placement have revealed that intraoperative navigation systems provide higher accuracy rates and safety than do free-hand techniques. The accuracy of various image-guided navigation systems has been studied; however, differences have not been well defined due to the lack of adequate evidence-based comparative studies. OBJECTIVE: A meta-analysis was conducted to focus on the variation in pedicle screw insertion among 3 navigation systems: a 3-dimensional fluoroscopy-based navigation system (3D FluoroNav), a 2-dimensional fluoroscopy-based navigation system (2D FluoroNav), and a conventional computed tomography navigation system (CT Nav). METHODS: We screened for comparative studies on different pedicle screw insertion navigation systems published through January 2017 using the Cochrane Library, Ovid, Web of Science, PubMed, and EMBASE databases. RESULTS: From 125 papers that were identified, 10 articles were finally chosen. The present comparative study included 8 retrospective clinical studies, 1 prospective clinical trial, and 1 randomized controlled cadaveric study. The prevalence rate of pedicle violation in the 3D FluoroNav group was significantly lower than the rates of the 2D FluoroNav group (relative risk [RR] 95%, confidence interval [CI]: 0.16-0.61, P < 0.01) and the CT Nav group (RR 95%, CI: 0.42-0.90, P = 0.01), and the rate of the CT Nav group was significantly lower than that of the 2D FluoroNav group (RR 95%, CI: 0.29-0.81, P < 0.01). CONCLUSION: Significant differences exist among CT Nav, 3D FluoroNav, and 2D FluoroNav. Our review suggests that 3D FluoroNav may be superior to the other 2 methods in reducing pedicle violation and that clinicians should consider 3D FluoroNav as a better choice.

[Cloning and tissue expression of CAST transcript â ¡ in goat].

Calpastatin (CAST) gene is closely related with meat quality in livestock and poultry. Based on the bovine and ovine mRNA sequences, the cDNA of CAST Ⅱ gene in goat was amplified successfully for the first time by using RACE-PCR. Results showed that CAST Ⅱ of goat was 2474 bp in length with an open reading frame (ORF) 1695 bp long and encoded 564 amino acids, and there were four conserved domains and one conserved seven-peptide domain in amino acids sequences. Bioinformation analysis indicated that its secondary structures mainly were random coil and helical regions, and contained rich hydrophobic regions, certain phosphorylation sites, and protein kinase C (PKC) sites. Meanwhile, analysis of tissue expression of the gene in Tianfu meat goat demonstrated it was expressed in seven selected tissues. When the goat was of 6-month age, the highest expression was observed in longissimusdorsi, which was significantly higher than that of crureus (P<0.05) and other internal organ tissues (P<0.01).Furthermore, the expression of CAST II increased with the rise of the age and became the highest when the goat was at three-year age.

Molecular cloning and characterization of caprine calpastatin gene.

Calpastatin (CAST) is an important gene for meat quality traits in livestock and poultry. The cDNA of caprine CAST gene was amplified for the first time using RACE-PCR. Results showed the full-length cDNA of caprine CAST gene (Accession no. GU944861) was 2435 base pair (bp) and contained a 2187 bp open reading frame encoding a protein with 728 amino acid residues. Bioinformatic analysis indicated that caprine CAST cDNA was 89.8-95.4, 83.5-92.2, 72.8-81.8 and 69.8-73.5% identical to sheep, cattle, pig and human CAST cDNA. It was predicted that caprine CAST contained four conserved domains with 42 serine phosphorylation loci, 18 threonine phosphorylation loci, 1 tyrosine phosphorylation locus and 5 specific PKC phosphorylation loci. This work provided an important experimental basis for further research on the function of CAST in goat.