Determining the spatial scale of variation in soil radon concentration

Increasing concern about possible links between emissions of radon and certain types of malignant disease has led to local and regional surveys to measure radon concentrations in the soil and in dwellings. The spatial scale at which radon varies is largely unknown, and so efficient sampling schemes and methods of mapping cannot be selected. To determine the spatial scale of radon variation in the English Midlands we measured radon in the soil using solid-state nuclear track detection in three areas of different geological complexity. In two of them we used an unbalanced multistage sampling scheme with seven stages of nesting: the Hereford survey covered distances from 10 m to 7.5 km, and the Buxton survey distances from 1 m to 3.75 km. The results from the nested surveys suggested that geology exerts a strong control on the variation. Finally radon was measured every 20 m along a 2-km long transect which crossed several lithologies close to Nottingham. The soil radon values changed in an erratic way along the transect. The sample variogram of radon has a substantial nugget variance, suggesting that much of the variation occurred for distances less than the sampling interval. The structure at the longer scale seems to be controlled by the underlying geology. These results have implications for designing further surveys and for selecting a method of mapping. Stratification based on lithology might be the only feasible solution to sampling, estimating and mapping radon concentrations over large areas. Where the locally erratic component of variation is large, estimation by kriging, for example, would confer little additional benefit compared with that by classification.     

Appraisal of the carbon to nitrogen(C/N)ratio in the bed sediment of the Betwa River,Peninsular India

Bed sediment carbon to nitrogen(C/N) ratio is one of the essential variables reflecting sources of organic matter in river basins.In order to explore the spatial variability in sources of sediment C/N ratios,and the influence of land use and land cover(LULC) changes on the Betwa River basin in Peninsular India,51 river bed sediment samples were collected in December 2016.The coefficient of variation(CV) was35%indicating highly variable biogeochemical parameters.The sediment C/N ratio varied from 2.94 to 10.09.3.21-56.40,and 6.50-76.97 in upstream,mid-stream,and downstream regions,respectively,indicating a progressive change in sources of organic matter and depositional environment.The positive correlation between total carbon(TC) and C/N ratio was increasing in the downstream direction [upstream(+0.560) mid-stream(+0.603) downstream(+0.838)],which is an indication of high deposition and slow decomposition of sedimentary terrigenous organic matter distant from the regions of urban pollution.The LULC change analysis done by remote sensing and Geographic Information System(GIS)methods revealed an adverse change for the forests and barren land and a positive change for the agricultural land and built-up areas.The sediment C/N ratio mapping showed the impact of LULC changes on the sediment quality.The spatial distribution of bed sediment C/N ratio in the Betwa River basin has important reference value for managing organic matter transport in the downstream Yamuna River and Ganga River basin.     

Nested lumped‐parameter models for foundation vibrations

The concept of polynomial‐fraction approximation is explored in this article to develop a nested type of systematic lumped‐parameter model for unbounded soil. Based on the optimal coefficients determined from the flexibility formulation, the reciprocal of the polynomial‐fraction is first taken to represent the dynamic stiffness function of foundation and then decomposed into a linear polynomial and another polynomial‐fraction. The nested division introduced in this study is operated to generate a nested form for this decomposed polynomial‐fraction, which directly corresponds to a nested discrete‐element model. The nested type of lumped‐parameter model is then easily constructed by connecting this nested discrete‐element model in series with another simple discrete‐element model corresponding to the linear polynomial. Copyright © 2004 John Wiley & Sons, Ltd.     

目前短期气候预测可预报性的研究概况

气候的可预报性研究是气候变化研究的一个重要方面，作者首先介绍了短期气候预测之所以可行的两个主要原因，以及短期气候预测可预报性问题的实质；然后，较详细地介绍了目前研究月、季尺度时间平均可预报性的方差分析方法，包括了对实际大气和模式大气可预报性的研究；最后，对时间平均可预报性的研究结论进行了总结。     

NUMERICAL SIMULATION EXPERIMENTS BY NESTING HYDROLOGY MODEL DHSVM WITH REGIONAL CLIMATE MODEL RegCM2/CHINA

Based on improvement of a distributed hydrology-soil-vegetation model (DHSVM for short)and its application to North China,a nested regional climatic-hydrologic model system is developedby connecting DHSVM with RegCM2/China.The simulated climate scenarios,including controland 2×CO_2 outputs,are downscaled to 8 stations in Luanhe River and Sanggan River Basins todrive the hydrology model.According to simulation results,under double CO_2 scenarios,annualmean temperature and evapotranspiration will increase 2.8C and 29 mm,respectively;precipitation also increase but with different value for each basin,6 mm for Luanhe River Basinwhile 46 mm for Sanggan River Basin;runoff change for the two basins is different too,27 mmdecrease for Luanhe River Basin while 26 mm increase for Sanggan River Basin.As a result,therunoff in future for Luanhe River Basin and Sanggan River Basin will be 74 mm and 71 mm,respectively,which is approximately a quarter of annual mean runoff(284 mm)of the wholecountry.Total streamflow for the two basins will decrease about 2.5×10~8m~3.All these indicatethat the warm and dry trend will continue in the two river basins under double CO_2 scenarios.Thenested model system,with both climatic and hydrologic prediction ability,could also be applied toother basins in China by parameter adjustment.     

Post‐fire hydrological response and suspended sediment transport of a terraced Mediterranean catchment

In July 2013, a wildfire severely affected the western part of the island of Mallorca (Spain). During the first three post‐fire hydrological years, when the window of disturbance tends to be more open, the hydrological and sediment delivery processes and dynamics were assessed in a representative catchment intensively shaped by terracing that covered 37% of its surface area. A nested approach was applied with two gauging stations (covering 1.2 km² and 4.8 km²) built in September 2013 that took continuous measurements of rainfall, water and sediment yield. Average suspended sediment concentration (1503 mg L^?1) and the maximum peak (33 618 mg L^?1) were two orders of magnitude higher than those obtained in non‐burned terraced catchments of Mallorca. This factor may be related to changes in soils and the massive incorporation of ash into the suspended sediment flux during the most extreme post‐fire event; 50 mm of rainfall in 15 min, reaching an erosivity of 2886 MJ mm ha^?1 h^?1. Moreover, hysteretic counter‐clockwise loops were predominant (60%), probably related to the increased sensitivity of the landscape after wildfire perturbation. Though the study period was average in terms of total annual precipitation (even higher in intensities), minimal runoff (2%) and low sediment yield (6.3 t km^?2 y^?1) illustrated how the intrinsic characteristics of the catchment, i.e. calcareous soils, terraces and the application of post‐fire measures, limited the hydrosedimentary response despite the wildfire impact. Copyright © 2017 John Wiley & Sons, Ltd.     

Storm surge simulation along the Meghna estuarine area: an alternative approach

In this study, numerical prediction of surges associated with a storm was made through the method of lines (MOL) in coordination with the newly proposed RKARMS (4, 4) method for the meghna estuarine region, along the coast of Bangladesh. For this purpose, the vertically integrated shallow water equations (SWEs) in Cartesian coordinates were firstly transformed into ordinary differential equations (ODEs) of initial valued, which were then soloved using the new RKARMS (4, 4) method. Nested grid technique was employed for resolving the complexities of the region of interest with minimum cost. Fresh water discharge through the lower Meghna River was taken into account along the north east corner of the innermost child scheme. Numerical experiments were performed with the severe cyclone on April 1991 that crossed the coast over the study area. Simulated results by the study were found to be in good agreement with some reported data and were found to compare well with the results obtained by the MOL in addition with the classical 4th order Runge-Kutta (RK (4, 4)) method and the standard finite difference method (FDM).     

基于LGCP的城市管理事件空间点模式分析

数字化城管系统累积了大量城管事件历史数据,充分挖掘事件背后的空间分布模式和事件成因机制能够为城管部门的管控工作提供决策支持。论文利用Log Gaussian Cox Processes(LGCP)模型分析了西北某地H市P区的街面秩序类、市容环境类和宣传广告类城管事件之间的空间分布差异和事件成因影响差异。研究发现：① 3类城管事件都呈现出明显的空间聚集,其空间聚集尺度最远不超过924 m;② 各类事件聚集的特征各不相同,街面秩序类贴近城区主要干道,呈路网状。市容环境类表现出在城区中心块状聚集,周边地区零星分散的特征。宣传广告类靠近交通干线呈长条状,靠近商业中区域呈块状分布;③ 城区内不同类别的POI对城管事件的影响大小不同。购物服务类、医疗保健类和居民住宅类表现出最显著的影响,说明特定区域内人群的流量和密度是影响城管事件分布的重要因素,人群的流动和聚集会加剧城管事件数量的增加。研究结果能够满足城管部门的城管事件空间分布热点识别以及事件成因分析的需求。     

邻近性对人口再流动目的地选择的影响

中国人口流动进入总量稳定下的空间调整新阶段,存量流动人口的再流动成为塑造人口和城镇化格局的主体因素。本文从户籍地和前期流入地两个基点出发,综合考虑地理、制度、信息、社会、认知等维度,构建了双重多维邻近性影响人口再流动目的地选择的理论框架,利用全国流动人口动态监测调查数据和嵌套Logit模型开展实证研究。结果表明：双重多维邻近性对人口再流动的空间选择具有显著而稳健的影响。人口再流动时,会选择与自身知识水平更匹配、与户籍地和前期流入地都更近、信息联系都更强的城市,但社会联系仍主要依靠老家。流动人口具有回到户籍所在省（区、市）的主观意愿,但省内城市普遍机会不多、环境欠佳,缺乏吸引力。相对而言,女性对同乡网络的依赖高于男性;新生代流动人口在很多方面继承了老一代的特点,甚至比后者更依赖老家的信息和社会联系;高学历流动人口在流入地的深度社会融入使其能够利用本地化社会资本,再流动的空间选择也与流入地居民更为类似。     

半滑舌鳎促黄体激素受体基因片段的克隆及组织表达分析

采用巢式RT-PCR法克隆了半滑舌鳎Cynoglossus semilaevis促黄体激素受体(Luteinizing Hormonene Receptor, LHR)基因部分序列,经过BLAST比对,认为该序列与庸鲽、牙鲆、黑鲷、尼罗罗非鱼、青鳉和红鳍东方鲀的LHR基因同源性分别为97%,94%,85%,83%,82%和80%.该基因片段长度为614 bp,编码204个氨基酸,含有典型的跨膜螺旋结构区域(TM helix),属于糖蛋白激素受体(GHR)家族.组织表达分析表明,LHR基因在半滑舌鳎的卵巢、精巢、肝脏、胃、肠、鳃、心、脾、肾、头肾和脑中均有表达,表达量有所不同,以脾和肾中表达量最丰富.