广西龙虎山植物功能群物种多样性垂直格局

以样带法沿海拔梯度调查了广西龙虎山自然保护区植物群落、常绿植物功能群及落叶植物功能群物种多样性。垂直格局分析表明:乔木层α多样性垂直格局没有随海拔变化的明显规律;乔木层α多样性垂直格局在常绿植物功能群与落叶植物功能群之间差异较大,而在常绿植物功能群与群落物种多样性格局之间比较一致;乔木层β多样性垂直格局在群落、常绿植物功能群、落叶植物功能群之间大体一致;植物物种多样性垂直格局是垂直梯度上多种环境因子综合作用及不同植物功能群对垂直梯度环境因子不同响应的结果。地形和岩性的生态梯度分析表明:α多样性垂直格局与地形变化较一致,但没有随岩性变化而变化的明显规律;群落β多样性、落叶植物功能群β多样性与常绿植物功能群的β多样性垂直格局随岩性变化的趋势大体一致,但没有表现出随地形变化的明显趋势。      

(F,α,ρ,d)-凸和广义(F,α,ρ,d)-凸条件下一类多目标规划问题的对偶

对偶理论是最优化理论的重要组成部分,具有深刻的理论意义和重要的应用价值。针对多目标规划问题的对偶问题,在F-凸,ρ-凸和(F,ρ)-凸的基础上对(F,α,ρ,d)-凸和广义(F,α,ρ,d)-凸条件下的多目标规划问题进行了研究,将多目标非线性规划问题的Wolfe向量对偶,Mond-Weir型向量对偶和混合型向量对偶的弱对偶定理中的凸性条件弱化。在较弱的凸性((F,α,ρ,d)-拟凸,(F,α,ρ,d)-伪凸,弱(F,α,ρ,d)-拟凸)条件下,给出并证明了相应的弱对偶定理。通过弱化凸性条件,从而扩大了多目标规划的实用范围。     

Hydrodynamic-phytoplankton model for short-term forecasts of phytoplankton in Lake Taihu, China

Phytoplankton biomass is an important factor for short-term forecasts of algal blooms. Our new hydrodynamic-phytoplankton model is primarily intended for simulating the spatial and temporal distribution of phytoplankton in Lake Taihu within a time frame of 1-5 days. The model combines two modules: a simple phytoplankton kinetics module for growth and loss; and a mass-transport module, which defines phytoplankton transport horizontally with a two dimensional hydrodynamic model. To adapt field data for model input and calibration, we introduce two simplifications: (a) exclusion of some processes related to phytoplankton dynamics like nutrient dynamics, sediment resuspension, mineralization and nitrification, and (b) use of monthly measured data of the nutrient state. Chlorophyll-α concentration, representing phytoplankton biomass, is the only state variable in the model. A sensitivity analysis was carried out to identify the most sensitive parameter set in the phytoplankton kinetics module. The model was calibrated with field data collected in 2008 and validated with additional data obtained in 2009. A comparison of simulated and observed chlorophyll-α concentration for 33 grid cells achieved an accuracy of 78.7%. However, mean percent error and mean absolute percent error were 13.4% and 58.2%, respectively, which implies that further improvement is necessary, e.g. by reducing uncertainty of the model input and by an improved parameter calibration.     

Asteroseismic Analysis of a Cen B: Preliminary Tests of Effects of Rotation and Interior Magnetic Field in the Solar-like Star

Taking into consideration the effects of rotation and interior magnetic field during the lifetime of the star, we reconstruct the model of a Cen B to satisfy the latest nonasteroseismic and asteroseismic observational constraints. We find that the effects can induce a change of about 0.3 μHz in the large frequency spacings and can speed up the star's evolution. The model of a Cen B has thereby been improved.     

响应面法优化重组大肠杆菌生物合成别藻蓝蛋白(holo-apcA)的发酵条件

采用响应面法对重组大肠杆菌生物合成别藻蓝蛋白(holo-apc A)的发酵条件进行优化,提高了蛋白的表达量。以对重组别藻蓝蛋白α亚基在大肠杆菌中表达量影响较大的几种因素用于中心组合设计;中心组合设计试验结果表明诱导温度、培养基初始p H和诱导时机对诱导结果影响显著;经Design Expert 8.0软件优化后的最佳诱导条件为:诱导温度28℃,培养基初始p H 8.5,IPTG终浓度0.1 mmol/L,以及诱导时机3 h。最后验证试验得到的蛋白表达量在已有文献报道结果的基础上提高了70%~580%。中心组合设计-响应面法能够在有限的实验次数下,对影响生物过程的因子进行优化及对其交互作用进行评价,蛋白表达量达20.4 mg/L;IPTG用量由原来的1 mmol/L减少至现在的0.1 mmol/L,降低了发酵成本。     

铀矿找矿中α径迹测量方法的影响因素研究

我国于1974年开始将核径迹探测技术应用于铀矿勘探,其中α径迹测量是寻找深部隐伏铀矿的有效方法之一.本文对氡浓度大小、探杯尺寸、杯内表面放射性沉积物以及杯内底面固体放射性元素等对α径迹测量结果的影响进行了理论研究,建立了α径迹测量中不同装置结构及不同放射性元素对α径迹密度影响的理论公式,为该方法应用于铀矿勘探以及环境氡浓度测量提供理论参考依据.同时结合实验对比测量,进一步对理论公式进行验证,α径迹测量结果与理论计算所得结果吻合较好.研究结果表明：探测器上α径迹主要来源于氡,探杯尺寸不应小于氡致α径迹的最大有效探测尺寸.此外,放射性沉积物放出的α射线对测量结果有重要积极贡献,在铀矿勘探中,从提高探测灵敏度和减小测量结果不确定度的角度来看,其影响越大越好.在大多数测量装置尺寸下,探杯内底面以下的固态α放射性元素对径迹密度影响较小或无影响,实际测量时可将其忽略.