Response of Yesso scallop Patinopecten yessoensis to acute temperature challenge: physiological and biochemical parameters

Water temperature is generally considered to be a major factor affecting the physiological and biochemical activities of marine bivalves. Here, the physiological and biochemical responses of Yesso scallop, Patinopecten yessoensis, to acute water temperature changes in summer were studied. Scallops were transferred directly to a lower temperature (T_dec treatment) (from 23°C to 15°C) or to a higher temperature (T_dec treatment) (from 15°C to 23°C) for 72 h, respectively. Results showed that the oxygen consumption and ammonia-N excretion rates of P. yessoensis decreased significantly in the T_dec treatment but increased dramatically at 6 h in the T_dec treatment (P <0.05). In the T dec treatment, hepatopancreas antioxidant enzyme activities, superoxide dismutase (SOD) and catalase (CAT) activities, increased substantially within 72 h (P <0.05). However, a significant decrease in CAT activity was found at 12 h in the T_dec treatment (P <0.01). A significant enhancement of acid phosphatase (ACP) activity and malondialdehyde (MDA) content was detected when scallops were acutely exposed to a temperature of 15°C. The levels of Cu/Zn-SOD gene expression in their gills up-regulated significantly in response to acute temperature changes (P <0.01). These data suggest that acute temperature change affects physiological and biochemical functions, and improve our knowledge of P. yessoensis under conditions of thermal stress.

     

多源资料在青藏高原大气热源计算中的适用性分析

大气热源是高原气象学的理论要点,研究其计算方法及其适用性,对加深高原气象学的认识,开拓"高原气象学"课程学生的视野,都具有重要意义。然而,精确计算大气热源仍是个挑战。本文详细介绍了大气热源两种计算方法,即正算法和倒算法,并基于站点观测、卫星辐射资料(ISCCP和SRB)及4套再分析资料(NCEP/NCAR、NCEP/DOE、ERA-Interim和JRA55),比较了不同资料计算所得夏季高原热源多尺度变率的差异。结果显示利用正算法时,辐射资料的选择需慎重;而在利用倒算法时,再分析资料的选择则需根据热源的研究尺度而定,不同再分析资料差异颇大。就长期趋势变化而言,再分析结果Q_1-JRA55最接近观测;而在年际尺度上,Q_1-ERAI与Q_1-JRA55两套结果能近似重复观测计算所得热源变率;在季节内尺度上,多套再分析资料差异性缩小,均可细致刻画高原夏季热源变化周期,在高原地区均有较好的适用性。     

多腔扁钢管混凝土斜折柱抗震性能试验研究

大连国际会议中心结构幕墙柱中,采用了一种扁钢管混凝土斜折柱.文中结合该工程设计,进行了2个1/3缩尺的扁钢管混凝土斜折柱试件的低周反复荷载试验,1个试件为普通扁钢管混凝土斜折柱,1个试件为多腔扁钢管混凝土斜折柱.比较分析了两个试件的承载力、刚度、延性、滞回特性及破坏特征.研究表明:多腔扁钢管混凝土斜折柱与普通扁钢管混凝...     

西北太平洋热带气旋的闪电活动、雷达反射率和冰散射信号特征分析

利用热带测雨卫星(TRMM)携带的测雨雷达(PR)、闪电成像仪(LIS)和微波辐射计(TMI)的同步探测资料,选取1998-2008年登陆中国的46个热带气旋,分析了其不同强度阶段的闪电活动、雷达反射率和冰散射信号的分布特征,以及闪电的发生与雷达反射率和冰散射信号之间的关系.结果发现:强度较弱的热带气旋平均闪电次数相对较高;当强度达到强热带风暴阶段后,强度越强,闪电数量反而越少.热带气旋强度不同,闪电的空间分布也有差别,热带风暴、强台风和超强台风阶段眼壁区闪电密度最大,而其他阶段则在外雨带区密度最大.热带气旋大部分区域被层云和弱对流降水控制,0℃层以上雷达反射率迅速减小,冰散射信号也普遍较弱.虽然热带气旋的眼壁区对流活动最强.但相比于外面带却较不易发生闪电.在同等大小的雷达反射率下,闪电更易发生在台风和强热带风暴阶段,超强台风阶段发生闪电阈值最高.由于闪电的发生与软雹、冰晶和过冷水等微物理参量以及上升气流速度紧密相关,因此闪电资料可以提供关于热带气旋不同区域的微物理过程和动力过程信息.     

基于GIS的衡阳人居适宜度评价

参考当前人居环境评价方法和指标体系,结合生态位适宜度的基本原理与方法,从经济、社会、环境生态位三类独立指标出发,选取25项反映现实生态位与最适宜生态位之间耦合度的单项指标,构建了一种新的多指标城市人居环境质量定量评价的生态位适宜度模型.以湖南省衡阳市主城区为例,运用GIs技术和superMan Deskpro软件进行了...     

One-dimensional morphodynamic model for retrogressive erosion based on a sediment entrainment theory at high flow velocity

Retrogressive erosion is a high-speed erosion process that usually occurs during the rapid release of stored water in reservoirs built on sandy rivers.Retrogressive erosion has been utilized in the practice of reservoir sedimentation control,but accurate prediction of the bed deformation process by numerical models has rarely been reported.The current study presents a one-dimensional morphodynamic model for simulating the evolution process of retrogressive erosion induced by high-velocity flows on steep slopes.The governing equations apply a Cartesian coordinate system with a vertically oriented z axis.The bed surface gradient and friction terms in the flow equations include correction factors to take account of the effects of high slope on flow movement.The net vertical sediment flux term in the sediment transport and bed deformation equations is calculated using an equation of erosion velocity.Particularly,this equation is based on an empirical relation between the sediment entrainment rate and the Shields parameter in contrast to the traditional sediment transport capacity,and the critical Shields parameter is modified by taking into account the permeability of the sediment layer and the stability of particles on a slope.The feedback of scoured sediment on the flow movement is considered by additional terms in the governing equations.Flume experiments of retrogressive erosion in literature were simulated to validate the model.The temporal variations of the longitudinal profiles of the free surface and channel bed and the sediment transport rate were well predicted.The algorithm calculating sediment entrainment in the proposed model also was validated for an experiment measuring entrainment rate from the literature.More importantly,it was found that the morphodynamic model using the sediment transport capacity equation predicts the trend of cumulative erosion contrary to the measurements,while results of the proposed model can follow a similar trend with the observed data in the retrogressive erosion process.     

典型强龙卷风暴中的地闪活动特征

闪电活动对于强龙卷天气的发生有一定的指示作用,基于闪电定位资料,结合多普勒天气雷达、探空和ECMWF再分析资料对两次典型强龙卷风暴中地闪的时空演变、雷电流强度及正地闪活动特征进行了统计分析,结果表明:地闪主要发生在组合反射率因子≥30 dBZ的区域内,龙卷发生期间,地闪活动减弱且较为分散。不同龙卷风暴的地闪频次差异较大,这与风暴中上升气流的强度有关;当地闪频次从峰值降至最小值期间,龙卷及地,两次过程中地闪频次峰值分别提前龙卷发生约33 min和28 min。同时,龙卷及地之前,地闪会出现连续多次闪电跃增;龙卷等级越强,正地闪表现越活跃,特征越明显,在江苏盐城阜宁龙卷发生期间,还出现了地闪极性从正地闪主导向负地闪主导的反转;两次龙卷风暴雷电流强度随时间的变化规律并不明显,但均小于历史平均值,地闪发生愈频繁的龙卷风暴,对应的雷电流强度值愈小。      

基于高光谱的桂东北峰丛洼地土壤有机碳含量预测

以桂东北寨底峰丛洼地土壤为研究对象,利用二阶微分和去除包络线二阶微分方法对土壤光谱进行处理,筛选出3种光谱指数与土壤有机碳（SOC）相关系数最高的特征波段,通过比较偏最小二乘回归、多元线性回归与多元逐步回归等模型的精度,确定SOC最佳估测模型。结果表明:（1）研究区土壤样品有机碳质量分数最小值为 0.20%,最大值为6.06%,变异系数为63.28%,具有中等强度的空间异质性;（2）二阶微分光谱指数建立的多元线性回归模型精度优于原始光谱反射率及包络线二阶微分的模型;（3）二阶微分、包络线二阶微分光谱指数建立的偏最小二乘回归预测模型均比通过原始数据建立的模型精度高出0.3;（4）基于二阶微分所建立的多元逐步回归模型具有较高的预测精度（R2=0.75,均方根误差RMSE=4.83和较大的剩余估计偏差RPD=2.00）。      

基于雷达、卫星资料对河南省一次雷暴过程的地闪演变分析

利用地闪探测系统资料、多普勒雷达资料和卫星云图资料,分析了河南省一次雷暴过程的地闪特征及其与云体结构的关系,结果表明:在雷暴整个生命史中负地闪占据主导地位,占总地闪的99.5%;地闪平均强度与地闪频次存在负相关关系;初次地闪出现时雷暴强度迅速增强;40 d BZ强回波顶高、6 km高度50 dBZ强回波面积以及5 km高度之上50 dBZ强回波体积与地闪频次存在明显的正相关关系,在整个雷暴过程中的相关系数分别为0.80、0.91和0.93,而在雷暴不同发展阶段3种雷达参量与地闪频次的相关性有不同的变化趋势;地闪一般分布在6 km高度雷达回波≥40 dBZ、云顶亮温≤200 K的区域,有助于识别强对流区。