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Near-space high-altitude balloon-based platforms have a series of advantages and provide superior conditions for optical observation. In order to ensure the stability of the optical axis of the optical detection load and stable tracking of the target, a near-space high-altitude balloon-based high-precision pointing and tracking system was designed, which can compensate for changes in the pitch angle and azimuth angle of the platform during flight. The system includes a primary platform stable pointing system and a secondary precise tracking system. In the finished flight experiment, the primary platform pointing system and secondary precise tracking system on the balloon-based observation platform worked normally, providing a guarantee for the coronagraph's stable tracking and detection of the sun. The primary platform pointing system can realize ±1° pointing accuracy, and the simulated accuracy of the secondary precise tracking system is 4″, which guaranteed that the coronagraph obtained more than 20,000 images. In subsequent works, we will upgrade and optimize the whole system and conduct our next flight experiment in the future. [ABSTRACT FROM AUTHOR]

For the requirements of the multi-means observation and emergency monitoring of space objects, including space debris and near-earth asteroids, this paper analyzes the astronomical observation conditions in the stratosphere, which is the region of the earth's atmosphere between 18 km and 55 km of altitude. The results reveal that near space has a significantly superior sky background and observation environment than ground-based observation, with the values of transmittance in the visible band and near-infrared bands more than 0.91 and 0.988, respectively. The sky background radiance at 20 km is 2.5% of the ground in the visible band and near-infrared band, which is practical for daytime observation, and there is an advantage in the availability of observable hours without the influence of aerosols and turbulence, etc. Based on near-space aerostats, such as a high-altitude balloon, a new method of space object floating observation has been proposed, including the observation facilities and scheme. The simulation shows that it has an all-weather/all-day ability while adopting multi-band observation. Applying a telescope with 9.5 mag detective ability located on the aerostat, debris with the size of about 0.36 m can be observed at a 1000 km distance and phase angle of 100°, while the near-earth asteroid with the size of about 980 km can be observed at a 5 million km distance and phase angle of 40° during the daytime. With these advantages, the aerostat-based observation would be a beneficial supplement to the ground-based observation network. [ABSTRACT FROM AUTHOR]

In order to improve the control of a moving mirror control system and enhance the anti-interference ability of the system, active disturbance rejection control (ADRC) with parameter autotuning is proposed and applied to control a rotary voice coil motor (RVCM). Improved snake optimization (I-SO) was applied to tune and optimize ADRC's key parameters. To obtain excellent parameters efficiently, in the population initialization phase of SO, the quality and diversity of initial solutions were improved through a chaotic elite opposition learning algorithm. In the local search phase, a sine and cosine (SC) search mode was introduced to enhance the local search ability of SO. The simulation results show that I-SO can effectively find the ideal parameters. I-SO has excellent search capability and stability. The experimental control system of a moving mirror was established, and the effectiveness of the parameters optimized by I-SO was verified. ADRC with parameter autotuning showed excellent control in the moving mirror control system, and the stability of the optical path scanning speed reached 99.2%. [ABSTRACT FROM AUTHOR]

miRNAs play essential regulatory roles in many aspects of plant development and in responses to abiotic and biotic stresses. Here, we characterize Pu-miR172d, which acts as a negative regulator of stomatal density by directly repressing the expression of PuGTL1 in Populus ussuriensis. Quantitative real-time PCR and GUS reporter analyses showed that Pu-miR172d was strongly expressed in the guard cells of young leaves. Overexpression of Pu-miR172d significantly decreased stomatal density, resulting in increases in water use efficiency (WUE) and drought tolerance by reducing net photosynthetic rate, stomatal conductance, and transpiration. Molecular analysis showed that PuGTL1 was a major target of Pu-miR172d cleavage. Moreover, PuGTL1-SRDX plants, in which PuGTL1 is suppressed, phenocopied Pu-miR172d -overexpression lines with reduced stomatal density and enhanced WUE. The expression of PuSDD1 , a negative regulator of stomatal development, was significantly increased in young leaves of both Pu-miR172d -overexpression and PuGTL1-SRDX plants. RNA-seq analysis of mature leaves indicated that overexpression of Pu-miR172d decreased the expression of many genes related to photosynthesis. Our findings show that the Pu-miR172d/ PuGTL1 / PuSDD1 module plays an important role in stomatal differentiation, and hence it is a potential target for engineering improved drought tolerance in poplar. [ABSTRACT FROM AUTHOR]

We studied 17 ABC1 genes in Populus trichocarpa, all of which contained an ABC1 domain consisting of about 120 amino acid residues. Most of the ABC1 gene products were located in the mitochondria or chloroplasts. All had a conserved VAVK-like motif and a DFG motif. Phylogenetic analysis grouped the genes into three subgroups. In addition, the chromosomal locations of the genes on the 19 Populus chromosomes were determined. Gene structure was studied through exon/intron organization and the MEME motif finder, while heatmap was used to study the expression diversity using EST libraries. According to the heatmap, PtrABC1P14 was highlighted because of the high expression in tension wood which related to secondary cell wall formation and cellulose synthesis, thus making a contribution to follow-up experiment in wood formation. Promoter cis-element analysis indicated that almost all of the ABC1 genes contained one or two cis-elements related to ABA signal transduction pathway and drought stress. Quantitative real-time PCR was carried out to evaluate the expression of all of the genes under abiotic stress conditions (ABA, CdCl2, high temperature, high salinity, and drought); the results showed that some of the genes were affected by these stresses and confirmed the results of promoter cis-element analysis. [ABSTRACT FROM AUTHOR]

Aims: The present study aims to investigate the clinical outcomes of arthroscopic suture fixation in treating tibial eminence fracture with a retrospective study design of two years' follow-up., Methods: A total of 33 patients with imaging evidence of tibial eminence avulsion fractures who underwent arthroscopic surgery between 2008 and 2012 were included in this study. The inclusion criteria for the study were a displaced tibial eminence avulsion fracture and anterior knee instability of grade II or higher inskeletally mature patients. These patients were treated with arthroscopic suture fixation and followed with a mean period of 24 months. Anteroposterior and lateral radiographs were obtained 3 months postoperatively to assess fracture healing. At 24 months after surgery, all patients were evaluated by an independent orthopaedic professor with clinical examination like anteroposterior laxity (Lachman-Noulis and anterior drawer tests) and Rolimeter knee tester (Aircast, Vista, CA). Knee range of motion was evaluated actively and passively with a goniometer. Knee function was evaluated by the Lysholm and International Knee Documentation Committee (IKDC) scores. Knee radiographs in standing anteroposterior, standing lateral, and Merchant views were examined for alignment, joint space narrowing, and degenerative knee changes., Results: No major complication like infection, deep venous thrombosis, or neurovascular deficit happened peri-operatively. At the final follow-up, there were no symptoms of instability and no clinical signs of ACL deficiency. Radiographs showed that all fractures healed 3 months post-operative, but at the last follow-up, there was one person with degenerative changes like joint space narrowing in radiographs. Anterior translation of the tibia was 0.47 mm on average (0 to 2.5 mm) compared with the uninjured side. Range-of-motion measurement showed a mean extension deficit of 1.5° (0° to 5°) and a mean flexion deficit of 2.7° (0° to 10°) compared with the unaffected side. The mean Lysholm score was 96 (85 to 100), and the mean IKDC score was 94 (80 to 100). Overall, the IKDC grade was A (normal) in 24 patients (58%), B (nearly normal) in 8 patients (33%), and C (abnormal) in 1 patient (8%)., Conclusion: The present study demonstrated tibial eminence fractures in adults can be effectively treated with arthroscopic suture fixation.

We identified 75 dehydration-responsive element-binding (DREB) protein genes in Populus trichocarpa. We analyzed gene structures, phylogenies, domain duplications, genome localizations, and expression profiles. The phylogenic construction suggests that the PtrDREB gene subfamily can be classified broadly into six subtypes (DREB A-1 to A-6) in Populus. The chromosomal localizations of the PtrDREB genes indicated 18 segmental duplication events involving 36 genes and six redundant PtrDREB genes were involved in tandem duplication events. There were fewer introns in the PtrDREB subfamily. The motif composition of PtrDREB was highly conserved in the same subtype. We investigated expression profiles of this gene subfamily from different tissues and/or developmental stages. Sixteen genes present in the digital expression analysis had high levels of transcript accumulation. The microarray results suggest that 18 genes were upregulated. We further examined the stress responsiveness of 15 genes by qRT-PCR. A digital northern analysis showed that the PtrDREB17, 18, and 32 genes were highly induced in leaves under cold stress, and the same expression trends were shown by qRT-PCR. Taken together, these observations may lay the foundation for future functional analyses to unravel the biological roles of Populus' DREB genes.

We studied 17 ABC1 genes in Populus trichocarpa, all of which contained an ABC1 domain consisting of about 120 amino acid residues. Most of the ABC1 gene products were located in the mitochondria or chloroplasts. All had a conserved VAVK-like motif and a DFG motif. Phylogenetic analysis grouped the genes into three subgroups. In addition, the chromosomal locations of the genes on the 19 Populus chromosomes were determined. Gene structure was studied through exon/intron organization and the MEME motif finder, while heatmap was used to study the expression diversity using EST libraries. According to the heatmap, PtrABC1P14 was highlighted because of the high expression in tension wood which related to secondary cell wall formation and cellulose synthesis, thus making a contribution to follow-up experiment in wood formation. Promoter cis-element analysis indicated that almost all of the ABC1 genes contained one or two cis-elements related to ABA signal transduction pathway and drought stress. Quantitative real-time PCR was carried out to evaluate the expression of all of the genes under abiotic stress conditions (ABA, CdCl2, high temperature, high salinity, and drought); the results showed that some of the genes were affected by these stresses and confirmed the results of promoter cis-element analysis.