A spatial–temporal analysis of low birth weight prevalence in Georgia, USA

Low birth weight (LBW), defined as a live birth weighing <2,500 g, is a significant public health problem in the United States, especially a few states including Georgia. Although much work has been done to study the epidemiology of LBW in various regions, the spatial–temporal patterns of LBW prevalence in Georgia remain unclear to a large degree. This paper investigates the temporal trend of LBW rates over a time span of 11 years and the spatial clusters of LBW prevalence in the state of Georgia at the county level. Comparison is also made between race and gender groups, and between county groups of different socioeconomic statuses to uncover disparities. Results showed a steady and prevalent increase of LBW rate in the state over the study period. Three counties and two county clusters with significantly higher LBW rates than the state rate were detected for 1999–2001, while one more county and two more county clusters of high LBW rates were detected for 2007–2009. More urbanized counties were found to have a relatively lower LBW rate when compared with the less urbanized ones as groups. The findings from this paper are expected to provide valuable insights to better understanding the etiology of LBW and more effective allocating prenatal health care resources in the future.     

岩浆弧火成岩构造组合与洋陆转换

本文从岩浆弧的火成岩构造组合、主要地质特征和弧地壳成熟度几个方面,讨论洋陆转换作用及其过程。表征洋俯冲环境的火成岩构造组合主要有英云闪长岩—奥长花岗岩—花岗闪长岩(TTG)组合,高镁安山岩组合,镁安山岩组合,Adakite组合(即高锶低钇中酸性岩)与富铌弧玄武岩组合等。基于火成岩构造组合的配置,讨论了4种可能的洋俯冲壳的壳幔结构:(1)热的年轻的俯冲洋壳与上覆冷的幔楔岩石圈;(2)冷的老的俯冲洋壳与冷的幔楔岩石圈;(3)冷的老的洋壳与热的幔楔软流圈;(4)热的年轻的俯冲洋壳与上覆幔楔软流圈。讨论了弧岩浆前锋作为结构标志以及空间组成极性的构造意义;讨论了弧火山作用的时间极性与弧成熟度及其地壳厚度之间的正相关关系,提出岩浆弧地壳双层结构的模型,下地壳主要为玄武质的基性麻粒岩和角闪岩,上地壳为长英质的TTG片麻岩,相当于大陆壳形成的第一阶段,即新生陆壳。岩浆弧及其洋—陆过渡性的弧地壳是洋俯冲作用形成的洋陆转换带(或增生造山带)的最重要的记录。     

Cordilleran vein type Pb-Zn-polymetallic deposits of the Xidamingshan district, Guangxi, SW China: Fluid inclusion and geochemical studies

There are a lot of clastic-sedimentary-rock-hosted hydrothermal vein type polymetallic deposits in the Xidamingshan district, Guangxi, SW China. Two major ones of them, the Fenghuangshan Pb-Zn-Ag-Mn deposit and the Lujing Pb-Zn deposit, have been selected for fluid inclusion and geochemical research in this paper. From fluid inclusion microthermometry, it has been found that they were deposited from fluid with low salinities at medium to low temperatures and low pressures. From hydrogen, oxygen, sulfur and carbon stable isotope studies as well as some trace element composition of sulfides, we have got the conclusion that they were formed in an intrusion-related ore-forming system, which means that they belong to Cordilleran vein type deposits.     

Numerical simulation of micro-bubble drag reduction using population balance model

The phenomenon of drag reduction by the injection of micro-bubbles into turbulent boundary layer has been investigated using an Eulerian-Eulerian two-fluid model. Multiple-size group (MUSIG) based on population balance models, which resolve a wide range of bubble sizes taking into account the bubble break-up and coalescence have been used for this purpose. The simulated results are compared against the experimental findings of Madavan et al. [1984. Reduction of turbulent skin friction by micro-bubbles. Physics of Fluids 27, 356-363] and also other numerical studies explaining the sophisticated phenomena of drag reduction. For the two Reynolds number cases considered, the buoyancy with the plate on the bottom configuration is investigated, as from the experiments it is seen that buoyancy seem to play a role in the drag reduction. Numerical model employed in the investigation comprises of a micro-bubble laden flow wherein two independent sets of Reynolds averaged Navier-Stokes (RANS) transport equations were used to describe both the phases of the flow. The shear stress transport (SST) turbulence model is used as the turbulent closure for the primary phase and a zero equation turbulence model is used for the micro-bubbles. Change in the mean streamwise velocity profiles, void fraction, turbulence modification and other results are presented and discussed with corresponding change in the gas injection rates. The complex mechanism of drag reduction are scrutinised and explained in context to our numerical findings. Special attentions have been also devoted to divulge the effect of bubble coalescence and break-up caused by random collision and turbulent impact. Numerical results showed good agreement for the skin-friction coefficients against experimental data throughout various air injection rates. The MUSIG model was found to be one of the best candidates to resolve the bubble dynamics in micro-bubble-induced drag reduction problems.     

Fractional vegetation cover estimation in heterogeneous areas by combining a radiative transfer model and a dynamic vegetation model

ABSTRACT

A fractional vegetation cover (FVC) estimation method incorporating a vegetation growth model and a radiative transfer model was previously developed, which was suitable for FVC estimation in homogeneous areas because the finer-resolution pixels corresponding to one coarse-resolution FVC pixel were all assumed to have the same vegetation growth model. However, this assumption does not hold over heterogeneous areas, meaning that the method cannot be applied to large regions. Therefore, this study proposes a finer spatial resolution FVC estimation method applicable to heterogeneous areas using Landsat 8 Operational Land Imager reflectance data and Global LAnd Surface Satellite (GLASS) FVC product. The FVC product was first decomposed according to the normalized difference vegetation index from the Landsat 8 OLI data. Then, independent dynamic vegetation models were built for each finer-resolution pixel. Finally, the dynamic vegetation model and a radiative transfer model were combined to estimate FVC at the Landsat 8 scale. Validation results indicated that the proposed method (R²?=?0.7757, RMSE?=?0.0881) performed better than either the previous method (R²?=?0.7038, RMSE?=?0.1125) or a commonly used method involving look-up table inversions of the PROSAIL model (R²?=?0.7457, RMSE?=?0.1249).     

舟山渔港风暴潮模拟分析

渔港风暴潮研究对防灾减灾具有重要意义。本文构建了舟山海域嵌套网格的风暴潮模型,经天文潮与风暴潮实测资料验证效果良好。设计5个方向共14条台风路径,计算了2017年8月8?12日大潮期12～17级台风下舟山渔港的风暴潮位。结果表明,由于向岸风作用南侧SE向比北侧E向登陆台风所造成的最高风暴潮位高35.7%,差值可达82 cm;对于两端通海的舟山渔港,南侧0.5R处登陆的SE向台风,风向与东口门朝向一致而跟渔港走向斜交,有利于水体进入并滞留,此时风暴潮位最高。南侧12级台风下ESE、SE、SSE发生漫堤,而北侧登陆台风无漫堤风险,沉降等原因造成海堤防台能力两头低于中段;数值试验显示,若在小干岛东侧设置丁坝,可将17级台风作用下的漫堤概率由26.23%减为10.66%。     

Reductive dechlorination of polychlorinated biphenyls is coupled to nitrogen fixation by a legume-rhizobium symbiosis

Chlorinated persistent organic pollutants, including polychlorinated biphenyls(PCBs), represent a particularly serious environmental problem and human health risk worldwide. Leguminous plants and their symbiotic bacteria(rhizobia) are important components of the biogeochemical cycling of nitrogen in both agricultural and natural ecosystems. However, there have been relatively few detailed studies of the remediation of PCB-contaminated soils by legume-rhizobia symbionts. Here we report for the first time evidence of the reductive dechlorination of 2,4,4′-trichlorobiphenyl(PCB 28) by an alfalfa-rhizobium nitrogen fixing symbiont. Alfalfa(Medicago sativa L.) inoculated with wild-type Sinorhizobium meliloti had significantly larger biomass and PCB 28 accumulation than alfalfa inoculated with the nitrogenase negative mutant rhizobium Sm Y. Dechlorination products of PCB 28, 2,4′-dichlorobiphenyl(PCB 8), and the emission of chloride ion(Cl-) were also found to decrease significantly in the ineffective nodules infected by the mutant strain Sm Y. We therefore hypothesize that N2-fixation by the legume-rhizobium symbiont is coupled with the reductive dechlorination of PCBs within the nodules. The combination of these two processes is of great importance to the biogeochemical cycling and bioremediation of organochlorine pollutants in terrestrial ecosystems.     

Controls of preferential orientation of earthquake- and rainfall-triggered landslides in Taiwan's orogenic mountain belt

Landsliding usually occurs on specific hillslope aspect, which may reflect the control of specific geo-environmental factors, triggering factors, or their interaction. To explore this notion, this study used island-wide landslide inventories of the Chi-Chi earthquake in 1999 (M_W = 7.6) and Typhoon Morakot in 2009 in Taiwan to investigate the preferential orientation of landslides and the controls of landslide triggers and geological settings. The results showed two patterns. The orientations of earthquake-triggered landslides were toward the aspect facing away from the epicenter in areas with peak ground acceleration (PGA) ≥ 0.6 g and landslide ratio ≥ 1%, suggesting that the orientations were controlled by seismic wave propagation. Rainfall-triggered landslides tended to occur on dip slopes, instead of the windward slopes, suggesting that geological settings were a more effective control of the mass wasting processes on hillslope scale than the rainfall condition. This study highlights the importance of the endogenic processes, namely seismic wave and geological settings, on the predesigned orientation of landslides triggered by either earthquake or rainfall, which can in turn improve our knowledge of landscape evolution and landslide prediction. © 2019 John Wiley & Sons, Ltd.