浮游植物metacaspase的分布、结构及其功能特性     

苏金净  蔡伟聪  李桂玲  李健  曾珺  刘静雯 《海洋与湖沼》2019,50(5):1059-1069

精氨酸/赖氨酸特异性半胱氨酸蛋白酶(Metacaspase)在浮游植物程序性细胞死亡(programmed cell death.PCD)过程中起着关键作用。本文利用生物信息学方法分析metacaspase基因在浮游植物中的分布,并以海洋球石藻(Emilianiahuxleyi)metacaspases(EhMCs)为代表分析其结构和功能,依据Uniprot和String数据库挖掘与metacaspase功能相关并参与浮游植物PCD过程的互作蛋白。结果发现:共计29条、四种类型的metacaspases分布于11种浮游植物中,它们的metacaspase蛋白一级结构存在明显差异,但位于p20的组氨酸和半胱氨酸活性位点均具有高度的保守性;EhMCs三级结构与酵母的metacaspase十分相似,暗示它们具有类似的功能;浮游植物metacaspases与多种蛋白存在直接或间接的互作关系,在细胞PCD过程、响应环境胁迫和能量代谢等方面发挥重要作用。另外.metacaspase的磷酸化修饰可能在浮游植物PCD信号转导过程中起调节作用。  相似文献   

Experimental study on hydrodynamic performance of SWATH vessels in calm water and in head waves     

《Applied Ocean Research》2019

An extensive experimental investigation on four SWATH hull forms has been conducted in calm water and in regular waves at University of Naples Federico II. Calm water tests have been analyzed in the range of Froude number Fr_T from 0.1 to 0.6. For all four SWATH configurations at the speed, corresponding to Fr_T 0.32, the behaviour in regular waves has been tested. The results of heave, pitch and vertical accelerations are presented in nondimensional form as RAO. For the “most promising” SWATH #4 configuration, a set of stabilizing fins have been designed and an active stabilization system has been developed. The developed SWATH#5 has been tested in calm water on three displacements in the range of Fr_T from 0.1 to 0.65. The dynamic wetted surface has been identified and the residual resistance coefficient C_R as well as R_T/Δ are reported. Seakeeping tests have been performed in regular head sea and in head and following irregular sea at Fr_T = 0.50. The conditions for the occurrence of dynamic longitudinal instabilities have been identified. The results allows to comment the effect of slenderness of struts and SWATH’s immersed bodies on resistance and seakeeping and concerns the applicability of SWATH concept to small craft.  相似文献   

海上风电升压站平台高程确定标准的合理性研究     

潘晓春 《海洋技术学报》2019,38(6):83-88

为保证海上风电升压电站建设的经济合理与安全可靠,合理确定海上风电升压电站平台高程十分必要。文中从波浪与潮位的遭遇组合、最大波高取值与现行相关标准的比较、最大波峰高度计算的合理性等方面,全面分析了确定海上风电升压站平台高程各组成项取值标准的合理性,研究认为现行标准明显偏高。建议海上升压站平台底部高程按"100年一遇极端高水位+重现期50年波列累积频率1%的最大波峰高度+安全超高"确定。结合工程实例计算分析,按本文建议可使海上升压站平台高程明显降低,从而节省工程造价,还可减轻升压站工程对周边风机的遮蔽影响,以达到多发电量的效果。  相似文献   

大气负荷对新疆地区地壳形变和地面重力变化的影响     

王海涛  王斌  王伟  章传银 《大地测量与地球动力学》2019,39(2):189-194

基于ECMWF全球大气模型和中国地面气候资料日值数据集中新疆及周边的气象站气压数据，根据弹性地壳形变理论，采用移去-恢复法，利用负荷格林函数法和球谐函数法，计算新疆及周边区域2011~2015年大气负荷变化对地壳垂直、水平形变的影响，同时采用大气导纳方法计算大气变化对地面重力的影响。结果表明，大气负荷对新疆地区垂直形变的影响达到cm级，对地面重力的影响可达10 μGal；大气负荷影响具有明显的季节性。  相似文献   

时间尺度重构EEMD-GRNN改进模型预测PM2.5的研究     

符海月  张祎婷 《地球信息科学学报》2019,21(7):1132-1142

合理构建PM_2.5浓度预测模型是科学、准确地预测PM_2.5浓度变化的关键。传统PM_2.5预测EEMD-GRNN模型具有较好的预测精度,但是存在过于关注研究数据本身而忽略其物理意义的不足。本研究基于南京市2014-2017年PM_2.5浓度时间序列数据,分析PM_2.5浓度多尺度变化特征及其对气象因子和大气污染因子的尺度响应,基于时间尺度重构进行EEMD-GRNN模型的改进与实证研究。南京市样本数据PM_2.5浓度变化表现为明显的天际尺度和月际尺度,从重构尺度（天际、月际）构建GRNN模型更具有现实意义;同时,PM_2.5对PM₁₀、NO₂、O₃、RH、MinT等因子存在多尺度响应效应,以其作为GRNN模型中的输入变量更具有时间序列上的解释意义。改进后的EEMD-GRNN模型具有更高的PM_2.5浓度预测精度,MAE、MAPE、RMSE和R²分别为6.17、18.41%、8.32和0.95,而传统EEMD-GRNN模型的模型有效性检验结果分别为8.37、27.56%、11.56、0.91。对于高浓度天（PM_2.5浓度大于100 μg/m³）的预测,改进模型更是全面优于传统EEMD-GRNN模型,MAPE为12.02%,相较于传统模型提高了9.03%。  相似文献   

GRB 170817A的洛伦兹因子和观测角          下载免费PDF全文

林一清 《天文学报》2020,61(1):6

伴随着引力波事件GW170817的短暴GRB (Gamma-Ray Burst) 170817A首次提供了双中子星并合与短暴相联系的直接证据.但是短暴GRB 170817A具有非常弱的光度,意味着观测的视线方向可能偏离喷流轴方向.根据短暴静止系的峰值能量E_(p,i)和各向同性光度L_(iso)。之间的关系以及洛伦兹因子Γ和L_(iso)。之间的关系估算了短暴GRB 170817A以及长短暴GRB 060614观测角与喷流边缘的夹角θ'_(obs)和洛伦兹因子Γ,结果表明GRB 170817A的Γ=45±27,θ'_(obs)=2.2±0.5°,而GRB 060614的Γ=214±93,θ'_(obs)=0.5±0.1°.这个结果相当于GRB 170817A的正轴各向同性光度L_(iso,on)=(2.1±0.7)×10~(49) erg·s~(-1),比典型的短暴少2-3个数量级.GRB 060614的L_(iso,on)=(5.12±1.91)×10~(51) erg·s~(-1)与典型短暴相当.这意味着GRB 060614可能属于短暴类型,而GRB 170817A可能本质上就是一个弱暴.  相似文献   

碎冰条件下单点系泊船舶动态响应特性研究     

杨佳东  吕海宁  王晋 《海洋工程》2019,37(2):29-39

为了研究不同单点系泊位置对极地系泊船舶在来冰角度改变时动态响应的影响,运用离散元方法(DEM),计算了船舶在60%密集度下,冰速为1.0 m/s、冰厚为1 m时不同角度的船冰阻力,结合系泊分析软件二次开发功能,计算分析系泊船舶在不同来冰角度和不同系泊位置下受上述冰情影响下的响应。通过对模拟结果与试验结果的对比,认为离散元方法(DEM)的数值模拟结果与试验结果吻合较好;单点系泊位置为距船头L/4时,系泊船舶能以最快速、最稳定的方式对来冰方向的变化做出响应。  相似文献   

2016年新疆呼图壁6.2级地震前b值异常特征研究   总被引：1，自引：0，他引：1       下载免费PDF全文

刘子璇  冯建刚  王维桐 《地震工程学报》2020,42(1):150-156

利用2009年以来中国地震台网中心地震编目资料,以2016年新疆呼图壁6.2级地震作为研究对象,采用最大似然法进行b值空间扫描计算,获取震前震中及其邻区地震b值的空间图像。研究结果显示,2016年呼图壁6.2级地震发生在震前显著低b值区域,该异常特征可能反映了地震孕育的应力积累过程,印证了b值的物理意义。  相似文献   

基于模拟退火算法的设计反应谱标定方法     

谭启迪  薄景山  常晁瑜  韩昕  乔峰 《地震工程与工程振动》2020,(1):155-161

反应谱的标定是抗震设计的基础工作之一,模拟退火算法是基于模拟固体退火过程而提出的多参数优化组合方法。本文提出将模拟退火算法应用于设计反应谱的标定,并概述了模拟退火算法的基本原理及特点,介绍了运用MATLAB基于模拟退火算法对反应谱进行标定的过程。检验了将模拟退火算法应用于场地相关谱标定的可行性和合理性,给出了将其应用于工程场地地震安全性评价中设计反应谱标定实例。通过检验和实例分析可以看出,基于模拟退火算法的反应谱标定方法所给出的设计反应谱谱形真实地反映了原地震反应谱的特征,较客观的反映了场地相关反应谱的峰值和周期特征。  相似文献   

Accuracy assessment of NLCD 2011 percent impervious cover for selected USA metropolitan areas     

《International Journal of Applied Earth Observation and Geoinformation》2020

The emergence of high-resolution land cover data has created the opportunity to assess the accuracy of impervious cover (IC) provided by the National Land Cover Database (NLCD). We assessed the accuracy of the 900 m² NLCD2011 %IC for 18 metropolitan areas throughout the conterminous United States using reference data from 1 m² land cover data developed as part of the United States Environmental Protection Agency’s EnviroAtlas project. Agreement was assessed from two perspectives: 1) sensitivity to the size of the assessment unit used for the comparison, and 2) utility of NLCD %IC to serve as a proxy for high-resolution IC. The former perspective was considered because statistical relationships can be sensitive to assessment unit size and shape, and the latter perspective was considered because high resolution (reference) %IC data are not available nationwide. The utility of NLCD %IC as a proxy for the high resolution data was assessed for seven lattice (square) cell sizes ranging from 1 ha to 200 ha using four EnviroAtlas IC indicators: 1) %IC per 100 ha (1 km²); 2) %IC by Census block group; 3) %IC within a 15 m (radius) of the riparian zone, and; 4) %IC within a 50 m (radius) of the riparian zone. Agreement was quantified as per assessment unit deviation (NLCD %IC – reference %IC) and summarized as Mean Absolute Deviation (MAD) and Mean Deviation (MD) both within and across the 18 metropolitan areas. Ordinary least squares (OLS) regression (y = reference %IC and x = NLCD %IC) was also used to evaluate the quality of the NLCD %IC data. MAD was ≤ 5% for six of the seven lattice cell sizes. MAD was also ≤ 5% for Census block groups > 100 ha and for both riparian units. These results suggest that uncertainty attributable to the measurement of %IC was no greater than the uncertainty related to the effect of IC on aquatic resources that have been derived from studies of aquatic condition (e.g., benthic fauna) over a range of %IC. Overall, agreement was variable from one metropolitan area to the next. Agreement improved as assessment unit size increased and declined as the level of urbanization (NLCD %IC) increased. NLCD %IC tended to underestimate reference %IC overall, but NLCD %IC was sometimes greater than reference %IC in urbanized settings.  相似文献