ABCD2评分法结合颅脑DWI及CTA预测TIA后脑梗死风险

目的：在ABCD2评分基础上,评估结合弥散加权成像（DWI）及CTA对短暂性脑缺血（TIA）后短期内发生脑梗死风险的预测价值。方法：连续选取本院2015年1月至2017年6月170例TIA患者（平均年龄62.4岁±5.4岁）,全部患者均行DWI及CTA检查,且随访3个月。分别于7天、3个月记录患者ABCD2评分、DWI阳性结果及CTA诊断大动脉粥样硬化（LAA）,以评估所有患者短期内发生脑梗死风险的预测价值。结果：170例患者中,68例（40%）患者DWI阳性,43例（25%）诊断LAA。DWI阳性患者中单侧肢体无力（OR=2.3;95% CI,1.1~4.8）,TIA症状持续时间≥ 60 min（OR=3.7;95% CI,1.4~9.9）,ABCD2> 5（OR=5.4;95% CI,1.5~18.8）,LAA（OR=2.7;95% CI,1.3至5.5）。随访期间,7天内发生脑梗死1例,7天至3个月内发生脑梗死6例,ABCD2评分> 5（OR=24.4;95% CI,2.5~238.7）,DWI阳性结果（OR=9.8;95% CI,1.1~83.1）,LAA（OR=20.4;95% CI,2.4~175.1）。除1例患者外,3个月内发生脑梗死的DWI均为阳性。ABCD2评分、DWI阳性结果及LAA与7天、3个月脑梗死风险的增加是相关联的。结论：在ABCD2评分基础上引入DWI和CTA检查作为辅助,能提高对TIA后发生脑梗死风险的预测能力。     

FRICTIONAL SLIDING OF PLAGIOCLASE GOUGE UNDER LOWER-CRUST TEMPERATURE AND RELATIVELY LOW EFFECTIVE NORMAL STRESS

The discovery of tremors on the lower crust portion of the San Andreas Fault has attracted more attention on the mechanical properties of the lower crust in recent years, and some experimental studies have been carried out to understand the mechanical behavior. Previous experiments under effective normal stresses of 200MPa have shown that pyroxene and plagioclase mineral separated from the gabbro and their mixtures all show velocity weakening in the lower-crust temperature range, which results in unstable slip when frictional sliding is the dominant deformation mechanism. This work is to examine whether the velocity-weakening behavior of plagioclase gouge also applies to relatively lower effective normal stress. Our experiments were performed under effective normal stress of about 100MPa, with a constant confining pressure control, with pore pressure of 30MPa and temperature of 100℃ to 600℃. We found that the frictional sliding of plagioclase are basically the same with the previous results obtained under effective normal stress of 200MPa, both of which show velocity weakening over the entire temperature range. The only difference is the out-of-trend drop of constitutive parameter a at 600℃ for the lower effective normal stress of 100MPa. It is thus concluded that reducing the effective normal stress has little effect on the sliding stability of plagioclase, and the previous conclusion made for mechanical behavior of the lower crust that unstable slips are possible therein also applies to the lower effective normal stress of 100MPa.     

中线调水前汉江中下游水量和水质本底特性及变化趋势分析

为研究南水北调中线工程调水前,汉江中下游的水量和水质本底特性及变化趋势,选择汉江中下游6个水文站及4个水质观测断面,采用数理统计、Mann-Kendall检验和Spearman秩次检验法,分别从水量和水质两个方面进行了分析。研究结果表明:(1)对比分析历史长序列流量资料,1999~2013年间汉江中下游地区处于偏枯期;(2)汉江中下游水量的年际变化较大,极值比介于2.7~3.3之间。水量年内各月分配变化也较大,汛期径流量占全年的63%~66%,非汛期仅占全年的34%~37%;(3)汉江中下游地区各水文测站的年均流量序列,总体上随时间变化的趋势均不显著,但经历了1980~1990的偏丰期及1990~2013的偏枯期;(4)汉江中下游地区的水质达标情况较好,大部分年份的水质均优于III类水质标准,且水质无显著的变化趋势。     

Application of low-pressure gas adsorption to nanopore structure characterisation of organic-rich lower Cambrian shale in the Upper Yangtze Platform,South China

The pores in shales are mainly on a nanometer scale, and the pore-size distribution is vital with regard to the preservation and exploitation of shale gas. This study focuses on the organic-rich lower Cambrian black shale in the Upper Yangtze Platform, South China and investigates their TOC, mineralogical composition and nanopore structure. Low-pressure N₂ and CO₂ adsorption experiments were conducted at 77.35 K and 273.15 K, respectively, and the nanopore structures were characterised by the modified Brunauer–Emmett–Teller, Dubinin–Radushkevich, t-plot, Barrett–Joyner–Halenda and density functional theory (DFT) methods. The results indicate the following. (1) The lower Cambrian shale has a high TOC content (1.77–7.23 wt%) and a high quartz content (27.7–51.6 vol%). The total specific surface area varies from 12.02 to 28.87 m²/g. Both the total specific surface area and quartz content are positively associated with the TOC content. (2) Shale samples with a higher TOC content have a greater number of micropores, resulting in more complicated nanopore structures. Micropore volumes/surface areas and non-micropore surface areas all increase with increasing TOC content, indicating that TOC is the key factor determining the nanopore structure of the lower Cambrian shale. (3) A combination of N₂ and CO₂ adsorption provides the most suitable detection range (～0.3–60 nm) and is both highly reliable and accurate with regard to nanopore structure characterisation.     

甘肃西北部黑河流域水资源对下游生态环境变化的影响阈

从流域尺度水资源承载能力及其有限性、可变性和上下游关联性的角度,探讨了黑河流域下游区生态环境变化的影响阈,阐明了不同水文年中游区的安全引水量和不同目标下下游区的生态环境修复对水资源的需求阈.基于多年平均地表径流量37.8×108m3/a的安全引水量为13.97×108m3/a和枯水年份(95%保证率)的安全引水量为10.14×108m3/a,下游区初步改善生态环境的生态需水量为8.01×108m3/a.提出了中游区经济社会可持续发展的水资源保障阈,即未来20年生产生活安全需水量介于22×108～23×108m3/a之间.在此基础上,阐明了在中游区经济社会稳定持续发展目标约束下确保黑河流域下游区生态环境不断改善的流域水资源优化配置模式及对策.     

几种电法仪器在地质勘查中的应用

文章介绍了几类物探电法仪器的工作原理、技术特点和适用范围,强调了物探资料的合理解释必须与地质认识相结合的重要性,物探工作要做实做细,对物探原始资料要选择合理的方法与参量进行计算处理,结合一些具体的勘测实例,说明各种方法的有效性及其实际应用效果.     

大洋岩石圈拆沉与大陆下地壳拆沉：不同的机制及意义——兼评“下地壳＋岩石圈地幔拆沉模式”

拆沉作用（delamination）是地球科学中一个重要的科学问题。本文认为,大洋岩石圈拆沉和大陆下地壳拆沉是不一样的：（1）拆沉的物质不同。大洋岩石圈拆沉的物质包括大洋地壳、岩石圈地幔甚至一部分软流圈地幔,它们共同进入地幔深部;而大陆下地壳拆沉仅仅限制在下地壳,不包括岩石圈地幔。（2）拆沉的动力不同。大洋岩石圈拆沉是由板块俯冲引起的,是地幔对流的产物,因此是一种快速的主动的拆沉;而下地壳拆沉是由于下地壳加厚使下地壳密度增加引起的,还要求其下刚性的岩石圈地幔转变成塑性的软流圈地幔才有可能发生。因此下地壳拆沉要克服许多阻力才能实现,使拆沉成为一个漫长的过程,是慢速的和被动的拆沉。（3）拆沉的过程不同,大洋岩石圈拆沉是由板块俯冲触发的,俯冲导致碰撞,大洋岩石圈从根部断裂,拆沉进入地幔。大陆下地壳拆沉由地壳加厚开始,使下地壳转变为榴辉岩相;随后,岩石圈地幔减薄,直至全部转化为软流圈地幔;下地壳发生部分熔融,形成大规模的（埃达克质）岩浆,使下地壳榴辉岩的密度大于下伏的地幔,从而引发拆沉。大陆下地壳拆沉不大可能是整体进行的,可能是一块一块地被蚕食,被拆沉的。（4）拆沉后的效液压不同,大洋岩石圈地幔拆沉,使热的软流罪状地幔上涌,从而引发了一系列地质效应;如岩浆活动,地壳抬升,构造松弛以及随后的造山带垮塌等。而下地壳拆沉只引起地壳减薄,高原和山脉垮塌,并不伴有大规模的岩浆活动和地壳抬升等过程。（5）拆沉与岩浆活动的关系不同,主动拆沉导致大规模岩浆活动,而被拆沉是在大规模岩浆活动的基础上开始的。此外,文中还对“下地壳＋岩石圈地幔拆沉”模式提出了质疑,认为该模式有许多难以理解的问题和太多推测的成分,而且与现在保存的地质事实不符。     

电离层对台风响应的全过程的特例研究

作为特例研究,本文对1988年和1990年两次强台风影响期间的电离层多普勒记录及相应的台风资料进行了细致的相关分析,目的是利用多普勒记录的连续性优点来了解电离层对登陆（或近海）强台风通过声重波响应的演化全过程.分析表明,在这两次台风影响期间,电离层形态中除有明显的波状扰动（中尺度声重波）出现外,还有一些值得注意的新现象：波动的时间演化表现出明显的幅度逐渐增加以及频率由高频向低频转变,在振幅很大的情况下日落后同时出现扩展F（Spread-F）现象,显示了声重波在激发电离层不规则结构方面的种子作用.这一演化过程与电离层中TIDs的线性传播理论一致,文中开展了对这一现象的非线性数值模拟,模拟结果基本上也与上述观测现象相吻合.     

S-wave crustal and upper mantle's velocity structure in the eastern Tibetan Plateau——Deep environment of lower crustal flow

A teleseismic profile consisting of 26 stations was deployed along 30°N latitude in the eastern Tibetan Plateau. By use of the inversion of P-wave receiver function, the S-wave velocity structures at depth from surface to 80 km beneath the profile have been determined. The inversion results reveal that there is significant lateral variation of the crustal structure between the tectonic blocks on the profile. From Linzhi north of the eastern Himalayan Syntaxis, the crust is gradually thickened in NE direction; the crustal thickness reaches to the maximum value (~72 km) at the Bangong-Nujiang suture, and then decreased to 65 km in the Qiangtang block, to 57―64 km in the Bayan Har block, and to 40―45 km in the Sichuan Basin. The eastern segment of the teleseismic profile (to the east of Batang) coincides geographically with the Zhubalong-Zizhong deep seismic sounding profile carried out in 2000, and the S-wave velocity structure determined from receiver functions is consistent with the P-wave velocity structure obtained by deep seismic sounding in respect of the depths of Moho and major crustal interfaces. In the Qiangtang and the Bayan Har blocks, the lower velocity layer is widespread in the lower crust (at depth of 30―60 km) along the profile, while there is a normal velocity distribution in lower crust in the Sichuan Basin. On an average, the crustal velocity ratio (Poisson ratio) in tectonic blocks on the profile is 1.73 (σ = 0.247) in the Lhasa block, 1.78 (σ = 0.269) in the Banggong-Nujiang suture, 1.80 (σ = 0.275) in the Qiangtang block, 1.86 (σ = 0.294) in the Bayan Har blocks, and 1.77 (σ = 0.265) in the Yangtze block, respectively. The Qiangtang and the Bayan Har blocks are characterized by lower S-wave velocity anomaly in lower crust, complicated Moho transition, and higher crustal Poisson ratio, indicating that there is a hot and weak medium in lower crust. These are considered as the deep environment of lower crustal flow in the eastern Tibetan Plateau. Flowage of the ductile material in lower crust may be attributable to the variation of the gravitational potential energy in upper crust from higher on the plateau to lower off plateau.     

小肠空气灌肠双源CT检查与胶囊内镜小肠检查对比研究

目的:探讨小肠空气灌肠双源CT检查对小肠疾病的诊断价值。方法:15例临床怀疑小肠病变的患者,行双源CT检查前或后3天内行胶囊内镜检查。其中,男8例,女7例,年龄最大者42岁,最小者23岁。症状主要为腹痛10例,脓血便4例,不明原因消瘦1例,病程最长4年,最短1月。结果:胶囊内镜未见异常8例,双源CT检查亦未见异常;双源CT诊断克罗恩病4例,与胶囊内镜及临床诊断一致;胶囊内镜可疑肿瘤3例,双源CT发现2例并作出良恶性诊断,其中1例为空肠间质瘤,1例为回肠腺癌,经手术病理证实;仅1例胶囊内镜可疑3cm大小肿瘤,双源CT未见异常,结合MRI检查及临床,证实为假阳性。结论:小肠空气灌肠双源CT检查,不仅可以显示小肠器质性病变范围、与邻近结构的关系,而且可以结合临床鉴别炎性病变与肿瘤性病变,并对肿瘤性病变做出良恶性鉴别;还可以为胶囊内镜所见病变定位及排除假阳性问题。