A uniaxial micro-electro-mechanical systems (MEMS) micro-vibration mirror can be used to construct a new type of fringe projection profilometry (FPP) system. In FPP system calibration, some pixels may be calibrated worse than other pixels due to various error sources, which will affect the final reconstruction accuracy. In addition, there are some difficulties in calibrating the MEMS-based system because a projector using the uniaxial vibration mirror does not have focusing optics and can only project unidirectional fringes. In this paper, we developed an FPP system using a uniaxial MEMS micro-vibration mirror. To solve the calibration problems, we propose a calibration model suitable for the MEMS-based system and a pixel refinement method. These pixels with relatively large calibration errors are called outlier-pixels, which will significantly increase the error of the following 3D mapping. Therefore, the pixel refinement method classifies all pixels based on a frequency distribution histogram of calibration errors during calibration and prevents outlier-pixels from participating in the following 3D mapping. The experimental results show that the proposed method can improve the accuracy of 3D reconstruction, and the feasibility of the self-developed system is verified.
MiRNAs‐containing extracellular vesicles (EVs) possess the unique function of mediating intercellular communication and participating in many biological processes such as post‐transcriptional gene regulation of embryo implantation and placental development. In the present study, Illumina small‐RNA sequencing was used to identify differentially expressed (DE) miRNAs in serum EVs of pregnant (P) and non‐pregnant (NP) Kazakh sheep at Day 17 from mating. The specifically and differentially expressed miRNAs at early pregnancy in sheep were verified by using RT‐PCR. The target genes of DE miRNAs were predicted by bioinformatics software, and the functional and pathway enrichment analysis was performed on Gene Ontology (GO) and the Kyoto Encyclopedia of Genes and Genomes (KEGG) terms. A total of 562 miRNAs (210 novel miRNAs) were identified by sequencing, of which 57 miRNAs were differentially expressed, 49 were up‐regulated, 8 were down‐regulated and 22 novel miRNAs were specifically expressed in the pregnant sheep. Eight highly expressed known miRNA (miR‐378‐3p, miR‐320‐3p, miR‐22‐3p, let‐7b, miR‐423‐3p, miR‐221, miR‐296‐3p, miR‐147‐3p) in pregnant group were down‐regulated in the control group. miRNAs‐containing pregnancy‐related terms and regulatory pathways regulation were enriched using both GO and KEGG analyses. Moreover, we also envisioned a miRNA‐mRNA interaction network to understand the function of miRNAs involved in the early pregnancy serum regulatory network. The results of RT‐PCR verification confirmed the reliability of small‐RNA sequencing. Among them, miR‐22‐3p and miR‐378‐3p were significantly differentially expressed (DE) between pregnant sheep and non‐pregnant group (p < 0.01). The site at which oar‐miR‐22‐3p binds MAPK3 was determined with a dual‐luciferase system. This is the first integrated analysis of the expression profiles of EV‐miRNAs and their targets during early pregnancy in ewes. These data identify key miRNAs that influence the implantation of sheep in the early stage of pregnancy, and provide theoretical basis for further molecular regulatory mechanisms research.
Fringe projection profilometry using a uniaxial MEMS micro-vibration mirror is becoming popular in three-dimensional (3D) reconstruction owing to the advantages of fast projection, small size, low cost, and no demand of focus optics. The calibration method is crucial and directly affects the accuracy of 3D reconstruction. In conventional phase-height calibration methods, there exists a problem of recalibration of system parameters if the maximum fringe frequency varies between the stages of calibration and reconstruction. In this paper, the fringe projection is realized by a MEMS mirror with a 1.15 kHz resonant frequency and a line laser. The voltage of line laser is modulated according to the scanning position, which is related to the vibration characteristics of MEMS mirror. Subsequently, the uniaxial MEMS-based 3D reconstruction system is constructed. We propose a novel calibration method for the uniaxial MEMS-based 3D reconstruction system. The proposed calibration method is derived from the scanning characteristics of a uniaxial vibration mirror and considers the camera distortion. The proposed method is free from the problem of recalibration and the limitations of installation. The experimental results show the proposed method can reconstruct the 3D shape of target in high resolution and verify the feasibility of the system.
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