Nitric oxide suppresses stomatal opening by inhibiting inward-rectifying K<Stack><Subscript>in</Subscript><Superscript>+</Superscript></Stack> channels in <Emphasis Type="Italic">Arabidopsis</Emphasis> guard cells

We explore nitric oxide （NO） effect on K^＋in, channels in Arabidopsis guard cells. We observed NO inhibited K^＋in, currents when Ca^2＋ chelator EGTA （Ethylene glycol-bis（2-aminoethylether）-N,N,N′,N;tetraacetic acid） was not added in the pipette solution; K^＋in currents were not sensitive to NO when cytosolic Ca^2＋ was chelated by EGTA. NO inhibited the Arabidopsis stomatal opening, but when EGTA was added in the bath solution, inhibition effect of NO on stomatal opening vanished. Thus, it implies that NO elevates cytosolic Ca^2＋ by activating plasma membrane Ca^2＋ channels firstly, then inactivates K^＋in, chartnels, resulting in stomatal opening suppressed subsequently.     

The global warming debate

Nowadays, global warming and the anthropogenic impact on the climate is one of the hottest topics of scientific re-search and world media interest. Concerns about this issue culminated with the Copenhagen Conference on December 7–18, 2009......     

Reconstruction of temperature series of China for the last 1000 years

This paper reports a study on reconstructing temperature series for ten regions of China over the last 1000 years with a time resolution of 10 a. The regions concerned are: Northeast, North, East, South China, Taiwan, Central, Southwest, Northwest China, Xinjiang and Qinghai-Tibet Plateau. A variety of proxy data, such as ice core, tree-rings, stalagmites, peat, lake sediments, pollen and historical records, were validated with instrumental observations made in the last 120 years, and applied in the recon- struction of the temperature series. A temperature series for whole China is then established by aver- aging the ten regional series with a weighting proportional to the area of each region. Finally, tem- perature variations for the last 1000 years are examined, with special focus placed on the characteris- tics of the Medieval Warm Period (MWP), the Little Ice Age (LIA), and Modern Warming (MW).     

基于有限样本信息准则的非协作盲信噪比估计算法

针对小样本条件下的盲信噪比估计误差较大问题,结合信号子空间分解方法,提出一种基于有限样本信息准则( finite sample information criterion,FSIC)的盲信噪比估计算法,并推导出基于FSIC盲信噪比估计算法的最大似然形式.在小样本情况下,FSIC的引入克服了传统信息论方法产生的过拟合和欠拟合问题,降低计算复杂度.在不需要已知信号调制方式、载波频率、波特率等先验知识的前提下,能够在加性高斯白噪声信道(AWGN)和多径信道(Rayleigh)下对常用调制信号进行有效的信噪比估计.在信噪比-25 dB～25 dB范围内,其平均估计误差小于1 dB,表明该算法可有效应用于小样本盲信噪比估计.     

Evidence and modeling study of droughts in China during 4―2 ka BP

Four periods with predominated droughts are identified in 4-2 ka BP according to documentary data, namely 3.6-3.5, 3.1-3.0, 2.8-2.7, and 2.45-2.35 ka BP. Palaeo-environmental data indicated that droughts were predominated in 4-2 ka BP in the south of Northeast China, Inner-Mongolia, east of Qinghai-Tibetan Plateau, and South China. Modeling study shows that precession may be responsible for the occurrence of droughts in 4-2 ka BP, integrating the GCM with forcing of insolation.     

Atmospheric oscillations over the last millennium

The variations of global atmospheric oscillations over the last millennium, including the North Atlantic Oscillation (NAO), the North Pacific Oscillation (NPO) highly associated with the Pacific Decadal Oscillation (PDO), the Southern Oscillation (SO) and the Antarctic Oscillation (AAO), are studied and compared in this paper based on observations and reconstructed data. The cross correlation analysis of AAO, NAO and NPO shows that there is no significant relationship on interannual variation among them. However, the consistency on decadal variability is prominent. During A.D.1920–1940 and A.D.1980–2000, the positive (strong) phase was dominant and the negative (weak) one noticeable during A.D.1940–1980. In addition, the reconstructed atmospheric oscillations series demonstrate that the positive phase existed in the early of the last millennium for NAO and in the late of the last millennium for AAO, respectively; while it occurred in the mid-late of the last millennium for PDO and ENSO.     

Global cooling in the immediate future?

New perspectives regarding the possible cooling of the Earth’s climate as a result of solar changes are reviewed in this paper. The major findings include: (1) solar activity is weakening to its very low level, which is comparable with the level in the early 20th century; (2) the current grand solar maximum has already lasted for eight 11-year solar cycles and might end in the coming one/two 11-year cycles; (3) a grand solar minimum might prevail in the next 100–200 years; and (4) the number of sunspots in the coming solar maximum (M)-year, around 2013, is an important indicator that needs to be closely monitored.     

月球轨道器交会对接同波束VLBI测量差分相时延实时解算

同波束VLBI技术是解决月球轨道交会对接地面高精度引导的重要手段．传统的多频点同波束VLBI实时解算算法成功解算差分相位整周模糊度的概率较低,而事后统计修正求解整周模糊度的算法存在较大的时间滞后,从而直接影响月球轨道交会对接两个航天器地面定轨、定位的精度以及实时性．在此背景下,本文研究了应用于月球交会对接条件下的同波束VLBI差分相时延实时解算算法．首先给出了多频点同波束VLBI解算差分相时延及整周模糊度的原理,根据差分相关相位整周模糊和差分相时延实时及事后解算结果,对整周模糊度产生的原因进行分析通过求解精确差分群时延值、采用匹配搜索算法以及差分相位连接条件对传统实时解算算法进行改进,提出一种新的差分相时延实时解算算法．利用SELENE同波束VLBI观测数据进行实时解算．结果表明该算法成功解算模糊度的准确度达到95．49％,相对于传统解算算法准确度提高了5．45％．     

基于流态化技术硅粉直接氮化制备氮化硅粉

提出了一种基于流态化技术,利用硅粉直接氮化制备氮化硅粉的新工艺。在常温下,以氮气为载气,将硅粉快速流化并夹带离开供料装置,硅粉和氮气组成的气-固两相流进入到预热器中,预热后的混合物从底部进入到高温悬浮床的高温区,以稀相气力输送的方式连续穿过高温悬浮床,在高温常压下发生燃烧合成反应,最后在出口经冷却装置冷却后,由收集装置收集,得到氮化产物。借助SEM、XRD、元素分析和FTIR等方法分析了氮化产物的形貌、物相组成、化学成分以及价键结构。实验结果表明：对于平均粒径为2.7μm的硅粉,在反应温度为1653K, 反应时间为2.7min时,硅的转化率为53.4%,氮化产物为非晶氮化硅粉。通过理论预测,如果将反应温度升高至1723K,硅粉氮化7.1min后,其转化率可达99%。本文提出的方法可连续制备优质氮化硅粉,而且比现有的其他制备方法具有更高的生产效率。