CA-SSL: Class-Agnostic Semi-Supervised Learning for Detection and Segmentation

To improve instance-level detection/segmentation performance, existing self-supervised and semi-supervised methods extract either task-unrelated or task-specific training signals from unlabeled data. We show that these two approaches, at the two extreme ends of the task-specificity spectrum, are suboptimal for the task performance. Utilizing too little task-specific training signals causes underfitting to the ground-truth labels of downstream tasks, while the opposite causes overfitting to the ground-truth labels. To this end, we propose a novel Class-Agnostic Semi-Supervised Learning (CA-SSL) framework to achieve a more favorable task-specificity balance in extracting training signals from unlabeled data. CA-SSL has three training stages that act on either ground-truth labels (labeled data) or pseudo labels (unlabeled data). This decoupling strategy avoids the complicated scheme in traditional SSL methods that balances the contributions from both data types. Especially, we introduce a warmup training stage to achieve a more optimal balance in task specificity by ignoring class information in the pseudo labels, while preserving localization training signals. As a result, our warmup model can better avoid underfitting/overfitting when fine-tuned on the ground-truth labels in detection and segmentation tasks. Using 3.6M unlabeled data, we achieve a significant performance gain of 4.7% over ImageNet-pretrained baseline on FCOS object detection. In addition, our warmup model demonstrates excellent transferability to other detection and segmentation frameworks.Comment: Appeared in ECCV202

Power scaling of high-power linearly polarized fiber lasers with <10 GHz linewidth

In this work, an all-fiberized polarization-maintained (PM) fiber laser has been demonstrated with a near-top-hat-shaped spectrum. By optimizing the modulation signal to generate near-top-hat-shaped spectrums, a 3-kW PM fiber laser has been achieved at &lt;10 GHz linewidth with the polarization extinction ratio of 96% and beam quality of 1.156, which is the highest output power ever reported with approximately 10 GHz linewidth, and further scaling of output power is limited by stimulated Brillouin scattering. By decomposing the mode content, the proportion of the fundamental mode in the output laser is above 97%. The stimulated Raman scattering suppression ratio reaches 62 dB at the maximal output power

Variable Responsive Wettability Films via Electrospinning Induced by Solvents

Three kinds of interesting distinct wettability films are fabricated by a facile electrospinning technique. The films are composites of poly(N-isopropylacrylamide) and polystyrene but different precursor solvents. By taking advantage of the conformational changes of poly(N-isopropylacrylamide) chains and polystyrene chains in different solvents, the films exhibit responsive wettability variation to temperature

Fine Mapping and Whole-Genome Resequencing Identify the Seed Coat Color Gene in Brassica rapa.

A yellow seed coat is a desirable agronomic trait in the seeds of oilseed-type Brassica crops. In this study, we identified a candidate gene for seed coat color in Dahuang, a landrace of Brassica rapa. A previous study of Dahuang mapped the seed coat color gene Brsc1 to a 2.8-Mb interval on chromosome A9 of B. rapa. In the present study, the density of the linkage map for Brsc1 was increased by adding simple sequence repeat (SSR) markers, and the candidate region for Brsc1 was narrowed to 1.04 Mb. In addition, whole-genome resequencing with bulked segregant analysis (BSA) was conducted to identify candidate intervals for Brsc1. A genome-wide comparison of SNP profiles was performed between yellow-seeded and brown-seeded bulk samples. SNP index analyses identified a major candidate interval on chromosome A9 (A09:18,255,838-18,934,000, 678 kb) containing a long overlap with the target region recovered from the fine mapping results. According to gene annotation, Bra028067 (BrTT1) is an important candidate gene for Brsc1 in the overlapping region. Quantitative reverse transcription (qRT)-PCR revealed that BrTT1 mainly functions in the seed. Point mutations and small deletions in BrTT1 were found between yellow- and brown-seeded Dahuang plants. Collectively, the expression and sequence analysis results provide preliminary evidence that BrTT1 is a candidate gene for the seed coat color trait in Dahuang

Mechanical enhancement of bi-phasic electrospun nanofibrous films by optimizing composition and configuration

An understanding of the composition, structure and property relationship is essential for engineering high performance polymer nanofibers to meet the ever-increasing demands for various applications. Here, bi-phasic polymeric fibres were prepared using electrospinning followed by thermal bonding. By controlling the softness-stiffness of the composition and configuration, the mechanical properties of bi-phasic fibrous films were improved with the strength up to eight times higher than that of single counterparts. We demonstrate that compatible interfaces, increasing alignment, supramolecular chains and connected bonding points, are jointly responsible for the mechanical enhancement except the diameter previous thought. This strategy provides new ideas and directions to design high-performance materials, especially for polymer-based fibrous material

Accuracy verification and correction of ascending and descending SBAS- and MSBAS-InSAR in monitoring mining surface subsidence

To address the position offset and insufficient monitoring accuracy of surface subsidence in mining areas using the SBAS-InSAR, this study uses the MSBAS-InSAR method. However, the quality of correction results is poor owing to the ill-posed observation equation of MSBAS. Therefore, the SBAS-based decomposition method is used, which directly decomposes the ascending and descending SBAS monitored LOS results to circumvent the ill-posed problem of the MSBAS and obtain higher-accuracy 2D deformation results. A real mining area was taken as the research site and monitored using the SBAS, MSBAS, and the SBAS-based decomposition method. The accuracy and effectiveness of the surface deformation results obtained by these methods were compared and verified with the levelling data in the same period. The results show that the SBAS-based decomposition method can significantly reduce the position offset and improve the monitoring accuracy of single-track SBAS, and circumvents the ill-posed problem of MSBAS

Optimal Sr-Doped Free TiO2@SrTiO3 Heterostructured Nanowire Arrays for High-Efficiency Self-Powered Photoelectrochemical UV Photodetector Applications

Due to their high performance, photoelectrochemical ultraviolet (UV) photodetectors have attracted much attention, but the recombination of photogenerated electrons at the interface of photoanode/electrolyte limited further improvement of photoelectrochemical UV photodetectors (PEC UVPDs). Modification of TiO2 photoanode by SrTiO3 could improve the performance of UVPD, because the energy barrier that is established at the TiO2&ndash;SrTiO3 interface could accelerate the separation of the photogenerated electrons-holes pair. However, the recombination center that is caused by the preparation of TiO2@SrTiO3 core-shell heterostructured nanostructure decreases the performance of PEC UVPDs, which is still an important problem that hindered its application in PEC UVPDs. In this paper, we presented a Sr-doped free TiO2@SrTiO3 core-shell heterostructured nanowire arrays as a photoanode for the self-powered PEC UVPD. This will not only accelerate the separation of the photogenerated electrons-holes pair, but it will also reduce the recombination of photogenerated electron-hole pairs in the photoanode. The intrinsic effect of SrTiO3 reaction time on the J variations of UVPDs is investigated in detail. An impressive responsivity of 0.358 A&middot;W&minus;1 was achieved at 360 nm for the UVPD based on TiO2@SrTiO3 core-shell heterostructured nanowire arrays, which heretofore is a considerably high photoresponsivity for self-powered photoelectrochemical UVPDs. Additionally, this UVPD also exhibits a high on/off ratio, fast response time, excellent visible-blind characteristic, and linear optical signal response

Magnetic Treatment Improves the Seedling Growth, Nitrogen Metabolism, and Mineral Nutrient Contents in Populus &times; euramericana &lsquo;Neva&rsquo; under Cadmium Stress

This pot experiment was carried out to investigate the mechanism underlying nutrient metabolism and seedling growth responses to magnetic treatment following exposure to cadmium (Cd) stress. A magnetic device of 300 Gs was applied during Cd(NO3)2 solution treatment at 0 and 100 mM&middot;L&minus;1. One-year-old seedlings of Populus &times; euramericana &lsquo;Neva&rsquo; were treated with different Cd(NO3)2 solutions in the presence or absence of magnetic treatment for 30 days. Seedling growth and physiological&ndash;biochemical indexes were measured under Cd stress. The contents of ammonium (NH4+&ndash;N), nitrate (NO3&ndash;&ndash;N), and total nitrogen (TN) in leaves, as well as NH4+&ndash;N and TN in roots, were increased by magnetic treatment combined with Cd stress, although the NO3&ndash;&ndash;N content was decreased. The activities of nitrate reductase (NR), nitrite reductase (NiR), glutathione reductase (GR), and glutamate synthase (GOGAT) in leaves and the activities of NR, glutamine synthetase (GS), and GOGAT in roots were stimulated by magnetic treatment; conversely, the NiR activity in roots was inhibited by magnetic effects. Magnetic treatment improved the synthesis of cysteine (Cys) and glutamine (Gln) in leaves and reduced the contents of glutamic acid (Glu) and glycine (Gly), while the contents of Cys, Glu, Gln, and Gly were increased in roots. The contents of Ca, Mg, Fe, Mn, Zn, and Cu in leaves were increased by magnetic treatment under Cd stress, whereas the content of K was reduced. In roots, the contents of K, Ca, and Fe were increased by magnetic treatment under Cd stress, but the contents of Na, Mg, Mn, Zn, and Cu were decreased. Magnetization could regulate the uptake of mineral nutrients by roots and translocation from the roots to the aboveground parts by affecting root morphology. Magnetic treatment could also improve nitrogen assimilation and the synthesis of free amino acids by stimulating the activities of key enzymes