江西农村居民的消费倾向研究

运用凯恩斯等西方消费经济理论,对江西农村居民消费倾向变动特征进行了分析与探讨。结果表明,与全国农村居民平均消费倾向比较,江西农村居民的消费倾向较高,基本上保持稳定,长期边际消费倾向则呈现递减趋势,城镇化的消费效应是显著的。农村居民的双重身份,消费的示范作用以及政策、制度因素对农村居民消费倾向的影响亦很大。     

果子狸呼肠孤病毒结构的冷冻电镜三维重构

为建立呼肠孤病毒(RV)的三维模型,本研究利用冷冻电镜(cryo-EM)单颗粒三维重构技术获得了分辨率为10.6(A)的果子狸RV MPC/04株的三维结构.三维重构结果显示,果子狸RVMPC/04株具有哺乳动物RV典型的形态.该病毒由内外两层衣壳蛋白组成,呈二十面体对称结构.内衣壳的外面包裹着一层由200个μ13σ33异源六聚体复合物构成的外衣壳,三角形剖分函数T=13.同时我们还观察到了该病毒主要蛋白之间的连接方式.本研究探讨为不同宿主的RV的形态和结构比较研究提供了相关的数据.     

Comparing the minimum inhibitory and mutant prevention concentrations of selected antibiotics against animal isolates of Pasteurella multocida and Salmonella typhimurium

Historically, the use of antibiotics was not well regulated in veterinary medicine. The emergence of antibiotic resistance (ABR) in pathogenic bacteria in human and veterinary medicine has driven the need for greater antibiotic stewardship. The preservation of certain antibiotic classes for use exclusively in humans, especially in cases of multidrug resistance, has highlighted the need for veterinarians to reduce its use and redefine dosage regimens of antibiotics to ensure efficacy and guard against the development of ABR pathogens. The minimum inhibitory concentration (MIC), the lowest concentration of an antibiotic drug that will prevent the growth of a bacterium, is recognised as a method to assist in antibiotic dosage determination. Minimum inhibitory concentrations sometimes fail to deal with first-step mutants in bacterial populations; therefore dosing regimens based solely on MIC can lead to the development of ABR. The mutant prevention concentration (MPC) is the minimum inhibitory antibiotic concentration of the most resistant first-step mutant. Mutant prevention concentration determination as a complementary and sometimes preferable alternative to MIC determination for veterinarians when managing bacterial pathogens. The results of this study focused on livestock pathogens and antibiotics used to treat them, which had a MIC value of 0.25 µg/mL for enrofloxacin against all 27 isolates of Salmonella typhimurium. The MPC values were 0.50 µg/mL, with the exception of five isolates that had MPC values of 4.00 µg/mL. The MPC test yielded 65.52% (18 isolates) Salmonella isolates with florfenicol MICs in the sensitive range, while 11 isolates were in the resistant range. Seventeen isolates (58.62%) of Pasteurella multocida had MIC values in the susceptible range and 41.38% (12 isolates) had an intermediate MIC value. Mutant prevention concentration determinations as done in this study is effective for the antibiotic treatment of bacterial infections and minimising the development of resistance. The MPC method can be used to better control to prevent the development of antibiotic drug resistance used in animals.     

基于GWO-MPC的联合收获机喂入量控制方法与仿真实验

收获机作为农业生产的重要生产工具，其喂入量控制一直是自动控制领域研究的热点问题。本文通过分析收获机工作方式，建立收获时收获机喂入量变化模型。设计开发收获机作业参数监测系统，以小麦作为实验对象，在我国华北地区开展田间实验，验证系统喂入量监测精度并同步采集产量、含水率和作业速度等参数，系统喂入量监测平均相对误差为8.55%。以收获机在割台高度不变条件下保持额定喂入量为控制目标状态，收获机作业速度作为控制量，采用模型预测的方法对收获机喂入量进行仿真控制。采用灰狼优化算法优化二次规划的权值矩阵，仿真结果表明，权值矩阵优化后，喂入量控制平均绝对误差小于0.1 kg/s,平均降低38.1%。喂入量控制误差与收获区域的产量成反比，与含水率成正比。在相邻时域内产量、含水率变化较小的收获区域效果更好。