Engineered Bacterial Bioreactor for Tumor Therapy via Fenton‐Like Reaction with Localized H2O2 Generation

Synthetic biology based on bacteria has been displayed in antitumor therapy and shown good performance. In this study, an engineered bacterium Escherichia coli MG1655 is designed with NDH‐2 enzyme (respiratory chain enzyme II) overexpression (Ec‐pE), which can colonize in tumor regions and increase localized H₂O₂ generation. Following from this, magnetic Fe₃O₄ nanoparticles are covalently linked to bacteria to act as a catalyst for a Fenton‐like reaction, which converts H₂O₂ to toxic hydroxyl radicals (?OH) for tumor therapy. In this constructed bioreactor, the Fenton‐like reaction occurs with sustainably synthesized H₂O₂ produced by engineered bacteria, and severe tumor apoptosis is induced via the produced toxic ?OH. These results show that this bioreactor can achieve effective tumor colonization, and realize a self‐supplied therapeutic Fenton‐like reaction without additional H₂O₂ provision.     

二维逐步正交匹配追踪算法

在图像等二维信号的应用与处理上,常规压缩感知理论框架存在重构算法效果差、图像块效应明显、对噪声敏感等问题。针对这些问题,根据现有二维观测模型和二维重构算法设计思想,可以设计一种新的重构算法：二维逐步正交匹配追踪算法。该算法借鉴了相关一维重构算法的设计思想,通过每次迭代选取符合阈值条件的多列原子进而正交化处理的步骤,提升了重构效率,改善了恢复图像质量。理论分析和实验结果表明,提出的算法在重构时间得到控制的情况下,得到的图像信噪比有较大提升,超越了现有典型的二维重构算法。     

黑河流域2001~2017年植被变化特征及其可延续性评价

植被的变化特征是流域生态监测的重要内容和流域综合管理决策的基础信息。基于谷歌地球引擎(Google Earth Engine,GEE),利用空间分辨率为250 m的MODIS-EVI(Enhanced Vegetation Index)产品,研究2001~2017年黑河流域植被的时空变化趋势及延续性特征。结合气温、降水与河流径流量观测数据,分析黑河流域上游、中下游绿洲与非绿洲区植被变化的影响因素。结果表明:近17年来黑河流域植被年最大EVI值年均增幅为0.0039,年均新增植被面积为480.3 km^2。受气温、降水、耕地开垦、水资源管理措施及与其密切相关的地下水等因素的不同影响,上中下游表现出不同的变化特征。无论是年最大EVI值还是植被面积,中游的增加趋势最为显著,绿洲区较非绿洲区增加趋势更为明显。这种变化趋势短期内可能延续,但长时间内存在较大风险。研究为快速监测植被变化提供了示范,揭示了干旱区植被监测中长势变化与类型变化的同等重要性,流域植被变化的区域协同性对合理分水、加强地表-地下水协同管理等流域综合管理提出了更高要求。     

基于梯度采样的大数据交叉访问授权技术仿真

如何对数据进行授权管理,确保数据的机密性等至关重要。为此提出了一种基于梯度采样的大数据交叉访问授权方法。采用多项式变换技术,将数据转换为可直接使用双率数据进行采样的数学模型,推导出估计损失数据的梯度随机算法,并且在算法中加入遗忘因子实现数据的梯度采样。用户在进行数据访问前需要进行初始数据加密,然后在将其转交至重加密服务器进行处理。同时,进行代理重加密密钥的约束,分割重加密密钥,其中一部分交由云端代理重加密服务器进行处理,另一部分则为创建者所控制,实现大数据的交叉访问授权。仿真结果表明,所提方法相比传统方法性能有了一定程度的提高。     

Are arch‐conforming insoles a good fit for diabetic foot? Insole customized design by using finite element analysis

Plantar ulceration is one of the leading complications for diabetic patients. To reduce the risk of plantar ulceration, people with diabetic neuropathy often used custom insoles to offload high pressures from the metatarsal. However, the current custom arch‐conforming insoles, totally contact with the foot, could affect the flow of blood and produce adverse effects on foot ulcers. This study is aimed to propose novel custom insoles for diabetic foot and to make a comparison between the traditional insoles and the proposed one. The novel pressure‐relieving insole is a layered modular insole that includes eight layers of small cushions. The results showed that the current custom insoles would increase the insole volume and squeeze the space available for the foot, and then the constrictive box of the footwear could deteriorate the blood flow of the foot and produce adverse effects on foot ulcers. The novel insoles were found to reduce the peak pressure from 208.86 to 160.02 kPa. High pressure was not observed in the sensitive locations of diabetic foot in this study, and the novel insoles fit diabetic foot better.     

Construction of Retinal Vessel Segmentation Models Based on Convolutional Neural Network

Neural Processing Letters - Segmentation of retinal vessels in fundus images plays a very important role in diagnosing relevant diseases. In this paper, we have constructed automated segmentation...     

视听觉深度伪造检测技术研究综述

深度学习被广泛应用于自然语言处理、计算机视觉和无人驾驶等领域,引领了新一轮的人工智能浪潮。然而,深度学习也被用于构建对国家安全、社会稳定和个人隐私等造成潜在威胁的技术,如近期在世界范围内引起广泛关注的深度伪造技术能够生成逼真的虚假图像及音视频内容。本文介绍了深度伪造的背景及深度伪造内容生成原理,概述和分析了针对不同类型伪造内容（图像、视频、音频等）的检测方法和数据集,最后展望了深度伪造检测和防御未来的研究方向和面临的挑战。     

库区垂向分层水温在线监测技术研究与应用

大型水库建成蓄水后一般会产生垂向水温分层现象,研究库区垂向分层水温变化规律对水库制定科学的生态调度方案具有重大意义。通过对分布式光纤测温系统原理及应用范围的研究,利用系统集成、数据处理技术和数据比测方法在溪洛渡和向家坝水库坝前开展了垂向分层水温在线监测应用研究。应用情况表明:分布式光纤测温系统在稳定性,数据连续性和准确性等方面都能满足监测要求,可为库区水生态调度提供可靠的数据参考,为今后库区水温垂向在线监测应用提供了新的路径。     

Maritime cognitive radio spectrum sensing based on multi-antenna cyclostationary feature detection

ABSTRACT

With the development of the maritime transportation industry, the number of ships is increasing and the ships are becoming more intelligent. Due to the rapid development of maritime communication, the demand for communication spectrum is increasing. Therefore, the maritime cognitive radio (CR) system is an effective solution. Because of the multipath fading caused by sea surface and atmosphere has a more serious influence on communication signals, which increases the instability of the signal reception, the spectrum sensing technology in maritime cognitive radio is more challenging than the spectrum sensing on land. In order to solve this problem, a cyclostationary detection algorithm for multiple antennas in fading model is proposed. A maximum ratio combining algorithm based on optimal weight correlation value (OWCV-MRC) is proposed for the diversity gain and system performance degradation caused by diversity technology on multipath fading channels. The algorithm uses the correlation values of the attenuation gains on the two different branches as the weighting coefficients of each branch, thus improving the coefficient matrix in the maximum ratio combining (MRC) algorithm. The simulation results show that the proposed algorithm can effectively detect the target signal in the fading channel with ultra-low signal to noise ratio (SNR).