320排 CT 前瞻性心电门控容积扫描窄采集窗设置的临床评价?

目的：通过低心率下宽采集窗与窄采集窗图像质量与辐射剂量对比,明确窄采集窗320排 CT 冠脉造影的临床应用价值。方法：前瞻性选取2015年9月至2016年1月拟行 CTCA 且心率（HR）≤65次/min、心率变异度（HRv）≤ 5次/min 的患者80例,平均年龄51岁（范围：36岁～83岁）。所选患者随机分为 A、B 两组,其中 A 组（n =40）采集期相设置为 R-R 间期70％～80％。B 组（n =40）采集期相设置为 R-R 间期30％～80％。两组设置管电压100 kV,依据体质量指数自动设置管电流300～580 mA。评价并比较 A、B 两组辐射剂量与图像质量。结果：A、B两组辐射剂量差异具有统计学意义（2.02 mSv ±0.78 mSv vs 4.35 mSv ±0.85 mSv,t =-12.474, P =0.000）。A 和 B 两组可评估率差异无统计学意义（χ2 =0.215,P =0.643）。A 组平均评分3.61±0.53,B 组平均评分3.71±0.48,Z =-3.074,P =0.002,差异有统计学意义。A、B 两组主动脉根部衰减值差异无统计学意义（t =-1.132,P =0.261）。结论：320排螺旋 CT 窄采集窗设置可以提供可评估的图像质量,从而大幅度减少辐射剂量。     

秦皇岛石门寨亮甲山奥陶系剖面化学地层和旋回地层研究

根据秦皇岛石门寨亮甲山奥陶系剖面的化学地层和岩石地层特征,将亮甲山组(O1l)细分为下、中、上段。选取Fe/Ca、Ti/Ca作为古气候替代指标,开展时间序列分析。通过多窗谱法(MTM)和傅里叶变换法(FT),从Fe/Ca、Ti/Ca比值中共提取出两个明显的米兰科维奇旋回：长偏心率405 ka和短偏心率90 ka。基于长偏心率周期建立的天文年代标尺表明,亮甲山组沉积时长为6.2 Ma,平均沉积速率为14.68 m/Ma,其中亮甲山组下段(0.00~48.00 m)和中上段(48.00~91.00 m)的沉积速率分别为12.00 m/Ma和19.55 m/Ma;马家沟组下部的沉积速率为18.00 m/Ma。奥陶纪生物大辐射可能直接导致碳酸盐生产模式由以灰泥生产为主转变为以生物碎屑生产为主,并使亮甲山组下段与中上段之交碳酸盐沉积速率大幅增加。旋回地层分析显示,早、中奥陶世之交天文轨道周期变化引起的地球气候改变可能对奥陶纪生物大辐射有重要的调控作用。     

塔克拉玛干沙漠腹地地表辐射与能量平衡

利用2013年塔克拉玛干沙漠塔中流动沙面地表辐射、土壤热通量、土壤温湿度和湍流通量观测资料,分析了沙漠腹地地表辐射和能量收支特征及闭合状况。结果表明：除潜热通量外,其余地表辐射各分量和能量平衡分量的月平均日变化结果整体均表现为标准的单峰型日循环形态,其中R_s↓与R_s↑变化同步,R_l↑、R_l↓滞后R_s↓0.5 ~ 1 h。各分量均表现出夏季高、春秋季次之、冬季低的季节波动性。干旱和极低的植被覆盖造成沙漠腹地全年潜热通量始终较为微弱,约占净辐射的2.8%,感热通量成为能量的主要消耗形式,约占净辐射的49%。偶尔的降水会刺激潜热通量突然增加。地表反照率相对较高且稳定,日变化呈早晚大、正午小的“U”型趋势,并具有明显的冬季高、夏季低的季节波动性,年均值0.28,月均值0.25~0.32。能量残差各月的日变化也均呈单峰曲线,日出后和日落前能量闭合程度最佳,并出现过闭合现象,全年夏季小,春秋季次之,冬季较大,月平均日峰值5.1~99.9 W·m^-2。土壤表层热储存是影响该地区能量平衡的重要因子之一,考虑表层土壤热存储后,地表能量闭合率达75.3%,能量闭合率夏季 > 春季 > 秋季 > 冬季,白天相比夜间有大幅提升。     

采用AutoLISP语言开发辐射取样图件自动生成程序

采用AutoLISP语言开发了一套辐射取样图件自动生成程序,该程序完全自主开发,能实现取样图自动生成、自动解释功能,大大提高了辐射取样图件绘制的效率,且避免了手工绘图所带来的误差。     

碳酸盐型盐湖卤水的模拟太阳池结晶试验

在碳酸盐型盐湖提锂工艺中, 太阳池是一个重要组成部分, 目的是储存太阳能能量以结晶析出碳酸锂。文章利用加热方法首次在实验室条件下进行模拟太阳池结晶试验, 试验的蒸发量随着温度的升高而加大, 但蒸发量的不同对析盐结晶影响不大。在不同时间段模拟试验中, 24 h时间段的Mg2+析盐浓度较Li+大, 且随着时间的延长逐渐降低, 而Li+则相反;Mg2+析出速率随着时间的增加而逐渐降低, 而Li+析出速率基 本保持一致。在不同温度模拟试验中, 卤水主要组分总析出率与温度的升高呈正相关, 卤水中CO32?和Li+的浓度降低速度大于其他组分, CO32?和Li+的析出率远大于其他组分, 析出主要矿物鉴定结果均为扎布耶石     

High-Pressure Behavior of Copper Carbonate: Data from Malachite

Abstract: In-situ high-pressure energy dispersive X-ray diffraction experiments of malachite have been performed using diamond anvil cell and synchrotron radiation. The highest recorded pressure is up to 17.4 GPa. The experimental results reveal that malachite experienced two phase transitions at 0.7 and 7.8 GPa, and the last one is reversible.     

A Regional Scale Investigation of Climatological Tropical Convection and Precipitation in the Amazon Basin

This study constructs a regional scale climatology of tropical convection and precipitation from more than 15 years of monthly outgoing longwave radiation (OLR) and precipitation data on 2.5°× 2.5° latitude-longitude grid to examine the spatial and temporal patterns and variability of convection and precipitation in the Amazon Basin. A linear regression analysis also detects if any trends exist in the two datasets. The region of study extends from 15°N to 25°S and 30° to 80°W that encompass the Amazon Basin and surrounding fringe areas for the period from January 1979 through December 1995 for the OLR data and up to 1996 for the precipitation dataset. The basin-average mean monthly and seasonal climatology serve as a ‘baseline’ reference for comparison with the full time series of basin-average monthly OLR and precipitation to illustrate the interannual variability and identify anomalous periods of wet and dry conditions. A linear trend analysis of OLR data found small negative values across the Amazon Basin indicating a slight increase in convective activity over the period of study. The analysis of the precipitation time series, however, shows no coincidental increase in precipitation as would be expected with an increase in convective activity. Portions of Rondônia and Mato Grosso, areas that have undergone extensive deforestation, illustrate no trend in precipitation as suggested by GCM simulation results. The only area featuring any large change in precipitation occurs in a small area in the northwestern region of South America where a large positive trend in precipitation exists.     

A comparative analysis of DEM‐based models to estimate the solar radiation in mountainous terrain

Daily solar radiation estimates of four up‐to‐date solar radiation models (Solar Analyst, r.sun, SRAD and Solei‐32), based on a digital elevation model (DEM), have been evaluated and compared in a Mediterranean environment characterized by a complex topography. The models' estimates were evaluated against 40 days of radiometric data collected in 14 stations. Analyzed sky conditions ranged from completely overcast conditions to clear skies. Additionally, the role of the spatial resolution of the DEM has been evaluated through the use of two different resolutions: 20 and 100 m. Results showed that, under clear‐sky conditions, the daily solar radiation variability in the study area may be reasonably estimated with mean bias errors under 10% and root mean square error values of around 15%. On the other hand, results proved that the reliability of the estimates substantially decreases under overcast conditions for some of the solar radiation models. Regarding the role of the DEM spatial resolution, results suggested that the reliability of the estimates for complex topography areas under clear‐sky conditions improves using a higher spatial resolution.     

2009年7月22日日全食期间湖北沙洋地区电离层扰动分析

发生在2009年7月22日亚太地区的日全食,为人们研究电离层扰动提供了一次难得的机会.基于沙洋地区采集的高频(1 Hz)GPS数据,通过对日食当天与前后几天电离层VTEC(Vertical Total Electron Content)的变化分析,结果显示日食期间电离层VTEC含量均呈现出一种先下降再上升的“水槽”变化趋势,且VTEC下降达到2～5 TECU,下降幅度达33.1％,VTEC的最小值与食甚时刻延迟为25.2～147.6 s.在日全食后期有中等强度的磁暴发生,与日食相互重合叠加共同对电离层VTEC变化造成影响,使得VTEC变化明显异于前后几天,最后定量的分析了磁暴对VTEC的影响.     

利用F10.7和Mg II构建太阳极紫外辐射长时间序列

利用SOHO/SEM在1996-2008年的太阳EUV观测数据,比较和评估F10.7和Mg II作为EUV代理参数的代表性,不能支持Viereck等关于Mg II是比F10.7更好的代理参数的结论.通过比较对两种参数的多种回归计算结果,确立双因子极大似然估计方法构建EUV计算模式,通过模型计算结果与SEM观测数据比较,表明该模型能够很好地重建EUV数据系列.利用该模式,构建了1978年11月以来的太阳极紫外辐射数据序列.