MSGNet: multi-source guidance network for fish segmentation in underwater videos

Fish segmentation in underwater videos provides basic data for fish measurements, which is vital information that supports fish habitat monitoring and fishery resources survey. However, because of water turbidity and insufficient lighting, fish segmentation in underwater videos has low accuracy and poor robustness. Most previous work has utilized static fish appearance information while ignoring fish motion in underwater videos. Considering that motion contains more detail, this paper proposes a method that simultaneously combines appearance and motion information to guide fish segmentation in underwater videos. First, underwater videos are preprocessed to highlight fish in motion, and obtain high-quality underwater optical flow. Then, a multi-source guidance network (MSGNet) is presented to segment fish in complex underwater videos with degraded visual features. To enhance both fish appearance and motion information, a non-local-based multiple co-attention guidance module (M-CAGM) is applied in the encoder stage, in which the appearance and motion features from the intra-frame salient fish and the moving fish in video sequences are reciprocally enhanced. In addition, a feature adaptive fusion module (FAFM) is introduced in the decoder stage to avoid errors accumulated in the video sequences due to blurred fish or inaccurate optical flow. Experiments based on three publicly available datasets were designed to test the performance of the proposed model. The mean pixel accuracy (mPA) and mean intersection over union (mIoU) of MSGNet were 91.89% and 88.91% respectively with the mixed dataset. Compared with those of the advanced underwater fish segmentation and video object segmentation models, the mPA and mIoU of the proposed model significantly improved. The results showed that MSGNet achieves excellent segmentation performance in complex underwater videos and can provide an effective segmentation solution for fisheries resource assessment and ocean observation. The proposed model and code are exposed via Github1

Finishing the euchromatic sequence of the human genome

The sequence of the human genome encodes the genetic instructions for human physiology, as well as rich information about human evolution. In 2001, the International Human Genome Sequencing Consortium reported a draft sequence of the euchromatic portion of the human genome. Since then, the international collaboration has worked to convert this draft into a genome sequence with high accuracy and nearly complete coverage. Here, we report the result of this finishing process. The current genome sequence (Build 35) contains 2.85 billion nucleotides interrupted by only 341 gaps. It covers ∼99% of the euchromatic genome and is accurate to an error rate of ∼1 event per 100,000 bases. Many of the remaining euchromatic gaps are associated with segmental duplications and will require focused work with new methods. The near-complete sequence, the first for a vertebrate, greatly improves the precision of biological analyses of the human genome including studies of gene number, birth and death. Notably, the human enome seems to encode only 20,000-25,000 protein-coding genes. The genome sequence reported here should serve as a firm foundation for biomedical research in the decades ahead

Edge Doping Engineering of High-Performance Graphene Nanoribbon Molecular Spintronic Devices

We study the quantum transport properties of graphene nanoribbons (GNRs) with a different edge doping strategy using density functional theory combined with nonequilibrium Green’s function transport simulations. We show that boron and nitrogen edge doping on the electrodes region can substantially modify the electronic band structures and transport properties of the system. Remarkably, such an edge engineering strategy effectively transforms GNR into a molecular spintronic nanodevice with multiple exceptional transport properties, namely: (i) a dual spin filtering effect (SFE) with 100% filtering efficiency; (ii) a spin rectifier with a large rectification ratio (RR) of 1.9 ×106; and (iii) negative differential resistance with a peak-to-valley ratio (PVR) of 7.1 ×105. Our findings reveal a route towards the development of high-performance graphene spintronics technology using an electrodes edge engineering strategy

Artificial radionuclides recorded in recent sediments of Chinese lakes

Establishing accurate historical records of the distribution, inventory and source of artificial radionuclides in the environmental are important for environmental monitoring and radiological health protection due to its high toxicity, and useful for identification and risk assessment of possible future environmental inputs of radionuclides from nuclear weapons test and from the accidental release from the nuclear fuel reprocessing propocess and power plant reactor. We applied a sector-field iCP-MS to study the recent sedimentation in ca. 20 lakes across China via measurements of both Pu isotopes, besides the conventional radiometric determination of 210Pb and 137Cs. The results show that the Pu activity profile was in agreement with the 137Cs profile in a sediment core of Lake Hongfeng. Inventories were 50.7 Bq/m2 foe 239+240Pu and 1586 Bq/m2 for 137Cs. the average 240Pu/239Pu atom ratio was 0.185 +/-0.009, indicating that Pu originated from global stratospheric fallout rather than from direct tropospheric or close-in fallout from the Chinese nuclear testing conducted in the 1970s. In the sediment core of lake Chenghai, the 240Pu/239Pu atom ratio ranged from 0.166 to 0.271 with a mean of 0.195 +/-0.021, which was slightly higher than that of global fallout. The 239+240Pu/137Cs activity ratios ranged from 0.0155 to 0.0411, with a mean of 0.0215, and the 239+240Pu inventory was 35.4 Bq/m2; both 239+240Pu/137Cs activity ratio and Pu inventory were close to those values of global fallout at 20-30 N. Three peaks were observed for both 137Cs and 239+240Pu activities in the examined sediment core; they most probably indicated the maximum deposition of global fallout between 1963 and 1964, the fallout from a series of Chinese nuclear tests during the 1970s, and the deposition of resuspended Pu-bearing particles from the Chernobyl accident. based on the isotopic compositions of Pu and isotopes and 137Cs distribuution, the sources of artificial radionuclides and teh potential application of Pu isotopes for sediment dating, and regional and global artificial effects were discussed.2008 Third Asia-Pacific Winter Conference on Plasma Spectrochemistr

Switching, dual spin-filtering effects, and negative differential resistance in a carbon-based molecular device

We present ab initio calculations for spin-dependent electron transport in a molecular device constructed by two carbon chains capped with a phenyl ring, which is sandwiched between two zig-zag-edged graphene nanoribbon (ZGNR) electrodes, where the ZGNRs are modulated by external magnetic field. The coexistence of switching, dual spin-filtering effects, and negative differential resistance (NDR) in the model device is demonstrated with the theory of carbon π-electrons. Interestingly, a two-state molecular conformational switch can be realized by changing the orientation between the planes of phenyl ring and electrodes, where the majority-spin current modulation (ON/OFF ratio) is 170–479 within the considered bias window. Moreover, the device shows perfect dual spin-filtering effect and can generate and control a full dual spin-polarized current through either the source-drain voltage or magnetic configuration of the electrodes. The selective spin current is due to a dual selection rule, the symmetry match between two ZGNR electrodes spin channel, and the carbon chain’s spin selection in our system. In addition, the obvious NDR behavior has also been observed in our model

Artificial radionuclides in lake sediments

第8回環境放射能研究

Anomalous Plutonium Isotopic Ratios in Sediments of Lake Qinghai from the Qinghai-Tibetan Plateau, China

The vertical profiles of 239+240Pu and 137Cs activities, and 240Pu/239Puisotopic ratios are determined for three sediment cores of Lake Qinghai from the Qinghai-Tibetan Plateau, China, and compared with those in sediments of another three lakes (Lake Bosten, Sugan and Shuangta), the only existing ones closest to Lop Nor area, China\u27s nuclear weapons test site in the northwestern part of the country. The mean inventory of 47.7+/-18.7 MBq km-2 for 239+240Pu activity in Lake Qinghai is comparable to the average value of global fallout expected at the same latitude, yet the mean inventory of 1112.0+/-78.0 MBq km-2 for 137Cs is slightly lower than that of global fallout. Anomalously low 240Pu/239Pu isotopic ratios (0.038-0.125) were found in the 3-6.5 cm deep sediment layers, indicating the trace Pu input from early nuclear weapons research activities at the Atomic City in the lake\u27s watershed during the 1950-60\u27s. Model calculation indicated that the Pu input accounted for approximately 5-16 % of the total Pu inventory. The observation of low 240Pu/239Pu ratio in deep sediment layer provided a new time marker for recent sediment dating in the lake and around the area. The results are of great significance to the further understanding of sources, records and environmental impacts of global and regional nuclear activities in the environment, and provide important chronological information for further studies on water eutrophication process and climatic change, and reconstruction of pollution history of organic contaminants and heavy metals in the watershed of Lake Qinghai

Artificial radionuclides recorded in lacustrine sediments in Bosten and Qinghai Lakes, NW China

Goldschmidt 200