磁层系统的能量输入、输出与日地耦合

用１９７８年和１９８２年３６个磁暴期间的太阳风、行星际磁场（ＩＭＦ）和地磁资料，分析和检验已有的两类太阳风－磁层能量耦合函数．结果表明：Ａｋａｓｏｆｕ提出的耦合函数ε能大致地预报亚暴和磁暴的发生。ε开始起重要作用时即出现亚暴；电离层能耗达到饱和值是发生磁暴的标志。ε与磁层体系能耗之间有接近于对数量的线性关系．用１９７８－１９８６年的资料，分析环电流和极光区电离层能耗在１２１个太阳自转周内的分布表明，日面上可能存在相对持久的活动区域     

子午面内时变电离层模型及其边界条件

子午面内时变电离层模型（ＴＤＩＭＭＰ）既可以以给定的热层背景为输入,也可与子午面内热层环流模型（ＴＣＭＭＰ）耦合使用。该模型根据Ｃｈａｐｍａｎ基础理论,考虑了波长在１００ｍｎ以下共３５个谱段的太阳辐射和４种光化反应,得到Ｏ＋、Ｎｏ＋、Ｏ＋和Ｎ＋等４种离子的浓度和离子的运动矢量速度,进而根据准中性条件得到电子浓度．其计算网格可以根据具体问题的需要进行调节．通过使用５种不同的边界条件进行实验,发现二维电离层模型的数值模拟结果（特别是电离层的纬向结构）对边界条件的依赖性很强,这与单点或一维（沿高度方向）模型几乎不受边界条件影响的情况完全不同．在根据实验结果选定的合适的边界条件下,ＴＤＩＭＭＰ给出了与实测符合得十分好的电离层状态和结构,表明ＴＤＩＭＭＰ是一个适用于电离层中、大尺度现象研究的模型。     

A NON-DIMENSIONAL COUPLED NUMERICAL MODEL OF ALLUVIAL FLOW

ＡＮＯＮ－ＤＩＭＥＮＳＩＯＮＡＬＣＯＵＰＬＥＤＮＵＭＥＲＩＣＡＬＭＯＤＥＬＯＦＡＬＬＵＶＩＡＬＦＬＯＷＳａｉｅｄＳＡＩＥＤＩ（ＴｈｅｔｅｘｔｉｓａｂｒｉｄｇｅｄｂｙＤｒ．ＤＩＮＧＬｉａｎｚｈｅｎ）（ＷａｔｅｒＲｅｓｅａｒｃｈＬａｂｏｒａｔｏｒｙ，Ｓｃ...     

一次中强磁暴期间低纬电离层响应的CT成像

为考察赤道异常区电离层对中等强度磁暴的响应特性,用电离层ＣＴ成像方法重建电离层电子密度二维剖面．重建结果表明,暴时低纬电离层电子密度以降低为主,但暴相随纬度和高度而异;磁暴期间,赤道异常峰结构仍然存在,但恢复相期间峰的位置向赤道移动;磁暴急始之后约２０ｍｉｎ,在赤道异常峰区出现电子密度深度耗空,这种耗空遍及从底到顶的整个Ｆ区,朝赤道一侧显现水平梯度非常大的陡壁．这种与磁暴急始相联系的电子密度深度耗空现象很有意义,值得进一步研究．     

Spatial and temporal variation of gravity field in the capital region

Ｓｐａｔｉａｌａｎｄｔｅｍｐｏｒａｌｖａｒｉａｔｉｏｎｏｆ　ｇｒａｖｉｔｙ　ｆｉｅｌｄｉｎｔｈｅｃａｐｉｔａｌｒｅｇｉｏｎＣｈａｎｇ－ＣａｉＨＵＡ；（华昌才）ＹｏｎｇＧＵＯ；（果勇）Ｄｕａｎ－ＦａＬＩＵ；（刘瑞法）ＧａｎｇＸＩＡＯ；（肖钢），Ｊ．Ｔ．...     

OPTIMAL CONSTANT-STAGE CONTROL FOR TRANSIENT FLOW IN OPEN CHANNEL

ＯＰＴＩＭＡＬＣＯＮＳＴＡＮＴ－ＳＴＡＧＥＣＯＮＴＲＯＬＦＯＲＴＲＡＮＳＩＥＮＴＦＬＯＷＩＮＯＰＥＮＣＨＡＮＮＥＬ￥Ｎ－Ｓ．ＷａｎｇｒｏａｎｄＸ．Ｌ．Ｄｏｎｇ（ＡｓｓｏｃｉａｔｅＰｒｏｆｅｓｓｏｒ，ＷａｔｅｒＣｏｎｓｅｒｖａｎｃｙａｎｄＨｙｄｒｏｅｌ...     

东亚赤道异常区电离层CT诊断──实验及初步结果

国际上第一个低纬电离层层析（ＣＴ）探测台链于１９９３年１１月建成，并开始数据采集．该ＣＴ台链沿１２０°Ｅ子午圈由６个卫星信标差分多普勒接收站组成，北起我国上海，南至菲律宾的马尼拉，纬度覆盖范围约２０°．该台链专为电高层赤道异常区电子密度大尺度结构ＣＴ成像而设计，其目的是监测研究赤道异常形态与动力学、电离层等离子体泡、行优以及暴时磁层－电离层－热层耦合过程等重要的赤道与低纬区电离层现象．本文介绍该低纬电离层ＣＴ实验的有关技术问题，包括接收台站布设、实验设备、数据采集软件和数据预处理方法．文中还给出利用ＣＴ技术，由实测斜电子含量数据反演电离层电子密度二维分布图像的几个实例．结果表明，利用低纬电离层ＣＴ台链可以有效地监测电离层赤道异常及其它低纬电高层电子密度大尺度结构的时空变化．     

一次中强磁暴期间低续电离层响应的CT成像

为考察赤道异常区电离层对中等强度磁暴的响应特性,用电离层ＣＴ成像方法重建电离层电子密度二维剖面。重建结果表明,暴时低纬电离层电子密度以降低为主,但暴相随纬度和高度而异;磁暴期间,赤道异常峰结构仍然存在,但恢复相期间峰的位置向赤道移动;磁暴急始之后约２０ｍｉｎ,在赤道异常峰区出现电子密度深度耗空,这种耗空遍及从底到顶的整个Ｆ区,朝赤道一侧显现水平梯度非常大的陡壁。这种与磁暴急始相联系的电子密度深度耗     

标记乳糖基白蛋白SPIO作为磁共振肝细胞受体显影剂的实验研究

目的是探讨标记乳糖基白蛋白的超顺磁性氧化铁粒子（ＬＡＣ－ＨＳＡ－ＳＰＩＯ）作为配体与肝细胞膜去唾液酸糖蛋白受体（ＡＳＧ）特异性结合可能性;评价ＬＡＣ－ＨＳＡ－ＳＰＩＯ增强磁共振受体成像对大鼠微小肝癌灶的显示能力。方法：将Ｆｅ３＋Ｆｅ２＋混合液与ＬＡＣ－ＨＳＡ在碱性条件下制备出ＬＡＯ－ＨＳＡ－ＳＰＩＯ;应用　二乙基亚硝酸胺建立大鼠肝癌模型;电镜及Ｐｅｒｌｓ（普鲁士蓝）染色,观察ＬＡＣ－ＨＳＡ－ＳＰＩＯ在肝组织的颁;并比较ＬＡＣ－ＨＳＡ－ＳＰＩＯ增强前后大鼠肝癌的显示情况。得到结果是（１）Ｐｅｒｌｓ染色证实有ＬＡＣ－ＨＳＡ－ＳＰＩＯ分布到肝细胞浆内;电镜下也显示肝细胞膜表面及胞浆内有电子致密ＳＰＩＯ粒子分布;（２）注射小剂量ＬＡＣ－ＨＳＡ－ＳＰＩＯ可观察到明显明显肝脏强化效果,大鼠肝癌检出率由平扫３６．８％（７／１９）提高到７８％（１５／１９,Ｐ＜００１）。结论：ＬＡＣ－ＨＳＡ－ＳＰＩＯ是一种新型的具有肝细胞ＡＳＧ受体靶向性显影剂,对提高肝脏微小瘤灶检出率有章要价值。     

用理论模式研究电离层F_1－ledge的变化

利用一个时变电离层理论模式，研究武昌地区（３０．５°Ｎ，１１４．４°Ｅ）电离层Ｆ_１－ｌｅｄｓｅ现象．表明利用当前关于中性气体和太阳辐射的经验模式，观测到的Ｆ_１－ｌｅｄｇｅ出现与演化的基本规律将可基于现有电离层理论加以再现．指出较明显的Ｆ_１－ｌｅｄｇｅ结构同较低的中性原子－分子含量比有直接关系，并同原子－分子成份的过渡高度、背景温度及其垂直分布形态有一定联系．同Ｆ_１－ｌｅｄｇｅ形态相关联的Ｆ_１－Ｆ_２谷，其出现主要是由于亚稳态氧离子参与光化过程，以及电离气体参与具有一定垂直变化的输运过程．     

A stepwise-cluster forecasting approach for monthly streamflows based on climate teleconnections

In this study, a stepwise cluster forecasting (SCF) framework is proposed for monthly streamflow prediction in Xiangxi River, China. The developed SCF method can capture discrete and nonlinear relationships between explanatory and response variables. Cluster trees are generated through the SCF method to reflect complex relationships between independent (i.e. explanatory) and dependent (i.e. response) variables in the hydrologic system without determining specific linear/nonlinear functions. The developed SCF method is applied for monthly streamflow prediction in Xiangxi River based on the local meteorological records as well as some climate index. Comparison among SCF, multiple linear regression, generalized regression neural network, and least square support vector machine methods would be conducted. The results indicate that the SCF method would produce good predictions in both training and testing periods. Besides, the inherent probabilistic characteristics of the SCF predictions are further analyzed. The results obtained by SCF can presented as intervals, formulated by the minimum and maximum predictions as well as the 5 and 95 % percentile values of the predictions, which can reflect the variations in streamflow forecasts. Therefore, the developed SCF method can be applied for monthly streamflow prediction in various watersheds with complicated hydrologic processes.     

Intercomparison of210Pb measurements at GEOSECS station 500 in the northeast Pacific

During reoccupation of the GEOSECS-I test station in May, 1979, more than eighty 30-liter Niskin samples were collected in profile, many as replicates, for²¹⁰Pb intercomparison measurements by the WHOI, SIO and Yale groups. In addition to the inter-laboratory comparisons, the SIO group also carried out extensive experiments to test the effect of sample scavenging method. Pb equilibration time (storage effect), and filtration process on the measured²¹⁰Pb results.The intercomparison measurements indicate that there is a general agreement between the various sets of data. The sample set which allows a direct comparison at the same depth was available in most cases only between two of the three groups. The direct paired comparison shows that (1) the WHOI data are systematically 3% lower than the SIO data; (2) there are no systematic differences observed between the SIO and Yale data although the scatter is rather large; (3) the Yale data are systematically higher than the WHOI data by about 8%.The SIO experiments show that (1) the two scavenging methods employed (Fe(OH)₃ and Co-APDC co-precipitation) yield identical²¹⁰Pb results; (2) variation of Pb carrier equilibration time or of storage time has no discernible effect; (3) the filtration apparatus and procedure employed at this station do not result in²¹⁰Pb loss or contamination.The²¹⁰Pb profile structure and absolute concentration measured earlier at the same location (GOGO-II test station and GEOSECS station 347) agree with those of station 500 within 10%. The present profile shows a minimum²¹⁰Pb concentration around 500 m depth, marking the penetration depth of the flux of excess²¹⁰Pb from the atmosphere. There is a mild mid-depth maximum around 2500–3000 m. The²¹⁰Pb/²²⁶Ra activity ratio decreases monotonically from about 1 at the²¹⁰Pb minimum to about 0.5 near the bottom. The particulate²¹⁰Pb profile shows a systematic increase from the subsurface water to the bottom water by a factor of 5. This feature has been observed in many GEOSECS particulate²¹⁰Pb profiles.     

Equatorial spread-F (ESF) and vertical winds

The Equatorial Spread-F (ESF) phenomenon is recorded in ionograms as a hierarchy of plasma instabilities in the F-layer of the equatorial ionosphere. The ESF is characterized by irregularities in the plasma (electron and ion) density and electric field distributions perpendicular to the Earth’s magnetic field. Large scale irregularities are generated by a primary plasma instability that develops in electric fields and plasma densities. Other secondary instabilities then develop and generate irregularities at several scale sizes that often produce a plasma ‘hole’ or ‘bubble’ that rises up with high E×B velocities. The ESF/plasma bubble phenomenon has been studied extensively with experimental techniques and modeling, which revealed important features. In the bottom side F-layer, near sunset, when the vertical density gradient steepens as the layer is supported by the horizontal (North–South) Earth’s magnetic field lines against the omnipresent Earth’s gravitational acceleration (g), the plasma conditions can give rise to Rayleigh–Taylor (RT) type instability. But the observed day to day variability of the ESF occurrence suggested that other agencies may also be involved in generating the instability. Sekar and Raghavarao (1987) with linear theory, and Raghavarao, Sekar and Suhasini (1992), with non-linear numerical modeling, suggested that vertical downward (upward) winds in the ambient gas have the potential to cause (inhibit) the ESF/bubble phenomenon. The presence of downward winds near the equator was reported earlier. In this paper, we show evidence for the presence of downward winds collocated with irregularities in electric fields and plasma densities as revealed by an unique combination of highly accurate measurements with instruments onboard the DE-2 satellite. The observations reported here are also consistent with the notion that the build-up of the equatorial ionization anomaly (EIA) prior to local sunset is important for the ESF instability.     

Radium-226 measurements from three Geosecs intercalibration stations

This paper presents the results of²²⁶Ra intercalibration measurements made by three groups of investigators (LDGO, USC and SIO) on the seawater samples collected in profile at three Geosecs intercalibration stations. A common radium standard prepared from an NBS bulk standard for the Geosecs program has been adopted by all groups. At Geosecs-I station in the Northeast Pacific, the new²²⁶Ra results obtained from reoccupation of the station show that the agreement of the three groups has been significantly improved over the initial comparison made in 1970.At Geosecs-II in the Northwest Atlantic, the initial comparison of the²²⁶Ra profiles showed that the USC data were systematically higher than the SIO data by 1 radium unit of 10^?14 g/kg. This corresponds to a relative difference of 20% due to the very low radium content of Atlantic waters. The new results obtained from reoccupation of the station show that both the USC and SIO data are consistent with their previous data. Thus, a systematic difference of 1 radium unit still exists. However, the new LDGO profile falls in between those of USC and SIO, lying closer to the SIO profile.At Geosecs-III station in the Southwest Pacific, the²²⁶Ra measurements show that the LDGO data are systematically higher than the SIO data by about 10% above 3.4 km depth. Below this depth, both sets of data agree and show a sharp decrease in radium concentration. This radium discontinuity corresponds to the benthic front which is a density discontinuity separating the Deep and Bottom Water in the South Pacific.     

Ionospheric signatures of magnetospheric boundaries in the post-noon sector

Spatial structures in ionospheric electron density revealed in a tomographic image have been identified with auroral forms and related to their sources in precipitating particles observed by DMSP satellites. The observations of plasma enhancements relate to discrete auroral arcs seen in the post-noon sector, identified by both red- and green-line emissions measured by a meridional scanning photometer. The features lie within a very narrow latitudinal band on L-shells where the satellite detectors observed electron precipitation classified as from the boundary plasma sheet (BPS). The harder particles are identified with an E-region structure, while further north the precipitation is softer, resulting in a localised F-layer blob and 630.0 nm emissions. A steep gradient in plasma density represent a signature in the ionosphere of the central plasma sheet (CPS)/BPS boundary. A transition to a less-structured F-layer is found on crossing the convection reversal boundary.On leave from Artic Geophysics, University Course on Svalbard (UNIS), N-9170 Longyearbyen, Norway     

绞窄性肠梗阻MDCT表现

目的:探讨急诊中绞窄性肠梗阻的多排螺旋CT（MDCT）的影像表现。方法:分析经手术证实的29例绞窄性肠梗阻（SIO）患者的临床资料及MDCT资料,经多方位重建和多窗位的技术处理,对绞窄性肠梗阻患者CT的肠管影像改变（肠腔的扩张、积液、肠壁厚度、密度的改变）,肠系膜的CT影像改变（肠系膜的模糊积液、旋转、门静脉的变化）,腹腔内的CT影像改变（腹水、气腹）及增强CT影像改变（肠壁的强化改变,肠系膜血管是否栓塞）深入研究。结果:29例患者中共检出肠腔扩张、积液26例,肠壁密度变化、增厚18例,肠壁、门静脉内积气2例,肠系膜的模糊、积液19例,缆绳征11例,漩涡征9例,鸟嘴征5例,腹腔积液12例,肠系膜血管栓塞3例及肠壁不强化5例。结论:多排螺旋CT识别绞窄性肠梗阻的MDCT征象细节对提高绞窄性肠梗阻的诊断及其鉴别诊断有较好的应用价值。      

A 22-year cycle in the F layer ionization of the ionosphere

The double-sunspot-cycle variation in terrestrial magnetic activity has been well known for about 30 years. In 1990 we examined and compared the low-solar-activity (LSA) part of two consecutive cycles and predicted from this database and from published results the existence of a double-sunspot-cycle variation in total electron content (TEC) of the ionosphere too. This is restricted to noontime when the semi-annual component is well developed. Since 1995 we have had enough data for the statistical processing for high-solar-activity (HSA) conditions of two successive solar cycles. The results confirm the LSA findings. The annual variation of TEC shows a change from an autumn maximum in cycle 21 to a spring maximum during the next solar cycle. Similar to the aa indices for geomagnetic activity the TEC data show a phase change in the 1-year component of the Fourier transform of the annual variation. Additionally we found the same behaviour in the F-layer peak electron density (N_max) over four solar cycles. This indicates that there exists a double-sunspot-cycle variation in the F-layer ionization over Europe too. It is very likely coupled with the 22-year cycle in geomagnetic activity.     

高纬电离层特性的实例研究

本文利用EISCAT雷达资料讨论磁层-电离层耦合的高纬电离层效应。研究表明,即使在夏季极昼情况下,磁扰期间的磁层过程对高纬电离层形态的影响也远大于太阳紫外辐射的作用。高能粒子沉降使电离层E层的电子密度大大增加;而磁层对流速度变大会使F层内电离复合加强。因而,磁扰时经常出现n_e（E层）>_e（F层）的情况。此现象不仅与宁静时完全相反,而且与中低纬电离层形态变化也有很大差别。     

Dissolved oxygen as an indicator of bioavailable dissolved organic carbon in groundwater

Concentrations of dissolved oxygen (DO) plotted vs. dissolved organic carbon (DOC) in groundwater samples taken from a coastal plain aquifer of South Carolina (SC) showed a statistically significant hyperbolic relationship. In contrast, DO-DOC plots of groundwater samples taken from the eastern San Joaquin Valley of California (CA) showed a random scatter. It was hypothesized that differences in the bioavailability of naturally occurring DOC might contribute to these observations. This hypothesis was examined by comparing nine different biochemical indicators of DOC bioavailability in groundwater sampled from these two systems. Concentrations of DOC, total hydrolysable neutral sugars (THNS), total hydrolysable amino acids (THAA), mole% glycine of THAA, initial bacterial cell counts, bacterial growth rates, and carbon dioxide production/consumption were greater in SC samples relative to CA samples. In contrast, the mole% glucose of THNS and the aromaticity (SUVA(254)) of DOC was greater in CA samples. Each of these indicator parameters were observed to change with depth in the SC system in a manner consistent with active biodegradation. These results are uniformly consistent with the hypothesis that the bioavailability of DOC is greater in SC relative to CA groundwater samples. This, in turn, suggests that the presence/absence of a hyperbolic DO-DOC relationship may be a qualitative indicator of relative DOC bioavailability in groundwater systems.     

Equatorial Plasma Bubbles: Variation of the Longitudinal Distribution with Altitude

Geomagnetism and Aeronomy - The equatorial plasma “bubbles” that form at the bottom-side of the F-layer are affected by zonal plasma drift when they rise to greater altitudes. Under the...