1991年冬季菲律宾以东海流特征和盐度结构

本文根据１９９１年１１月１５日～１２月２０日中国世界大洋环流实验（简称ＣＷＯＣＥ）首航ＡＤＣＰ测流资料并结合日本气象厅的ＡＣＭ次表层测流资料（１９９２年１月２０日～２月１５日），描述了菲律宾以东的海流特征。同时应用该航次ＣＴＰ资料计算了各观测断面的地转流流量，并用盐度跟踪讨论了北赤道逆流（ＮＥＣＣ）、黑潮和棉兰老海流的水源。计算和分析表明，本航次期间有３个强流区，即黑潮源头区、棉兰老沿岸区和北赤道逆流区。此外，本航次本区海流特征与１９８６／１９８７ＥＮＳＯ事件同期的海流特征基本相同。

夏季北冰洋海冰边缘区海水温盐结构及其形成机理

利用 1 999年北极科学考察期间在海冰边缘区的三次考察数据 ,研究了北冰洋海冰边缘区的温度和盐度结构。将海冰边缘区分为机制不同的两大类 ,一类是暖水海冰边缘区 ,主要热源是外部暖水进入海冰边缘区携带的热量 ;另一类是冷水海冰边缘区 ,主要热源是太阳辐射加热。文中主要对冷水海冰边缘区进行了研究。虽然两个冷水海冰边缘区 (R区与T区 )温度结构不尽相同 ,但都存在表层以下水体中的温度极大值现象 ,R区的温度极大值位于2 0m左右 ,T区的位于 40— 5 0m左右的深度 ,可以认为是海冰边缘区的典型温度特征。作者认为 ,次表层暖水的热源是太阳辐射的直接加热 ,为此 ,建立了太阳加热引起海水次表层增暖的物理模型和简单的数学模型 ,获得了冰下海水在太阳辐射的作用下增暖的解析解。结果表明 ,部分太阳辐射能穿过海冰加热冰下海水 ,加热之初温度的极大值出现在近表层 ,随着时间的推移 ,海温极大值的位置向下移动 ,最终可以达到 40m左右 ,证明了仅仅依靠太阳的短波辐射就可以形成中间暖的水层。文中阐明 ,开阔海水更多的是上混合层和跃层结构 ,冰下海水主要是次表层暖水结构 ;冷水海冰边缘区的海水主要带有冰下海水的特征。由于次表层暖水的形成与海冰厚度关系很大 ,近十几年北冰洋海冰厚度的显著减少势必加?

Robust salt-dome detection using the ranking of texture-based attributes

The accurate interpretation and analysis of seismic data heavily depends on the robustness of the algorithms used. We focus on the robust detection of salt domes from seismic surveys. We discuss a novel feature-ranking classification model for saltdome detection for seismic images using an optimal set of texture attributes. The proposed algorithm overcomes the limitations of existing texture attribute-based techniques, which heavily depend on the relevance of the attributes to the geological nature of salt domes and the number of attributes used for accurate detection. The algorithm combines the attributes from the Gray-Level Co-occurrence Matrix （GLCM）, the Gabor filters, and the eigenstructure of the covariance matrix with feature ranking using the information content. The top-ranked attributes are combined to form the optimal feature set, which ensures that the algorithm works well even in the absence of strong reflectors along the salt-dome boundaries. Contrary to existing salt-dome detection techniques, the proposed algorithm is robust and eomputationally efficient, and works with small-sized feature sets. I used the Netherlands F3 block to evaluate the performance of the proposed algorithm. The experimental results suggest that the proposed workflow based on information theory can detect salt domes with accuracy superior to existing salt-dome detection techniques.

Three-Dimensional Structure of Optimal Nonlinear Excitation for Decadal Variability of the Thermohaline Circulation

The decadal variability of the North Atlantic thermohaline circulation(THC) is investigated within a three-dimensional ocean circulation model using the conditional nonlinear optimal perturbation method. The results show that the optimal initial perturbations of temperature and salinity exciting the strongest decadal THC variations have similar structures: the perturbations are mainly in the northwestern basin at a depth ranging from 1500 to 3000 m. These temperature and salinity perturbations act as the optimal precursors for future modifications of the THC, highlighting the importance of observations in the northwestern basin to monitor the variations of temperature and salinity at depth. The decadal THC variation in the nonlinear model initialized by the optimal salinity perturbations is much stronger than that caused by the optimal temperature perturbations, indicating that salinity variations might play a relatively important role in exciting the decadal THC variability. Moreover, the decadal THC variations in the tangent linear and nonlinear models show remarkably different characteristics, suggesting the importance of nonlinear processes in the decadal variability of the THC.

Preparation of water-soluble magnetic nanoparticles with controllable silica coating

This work provides a general method for preparing monodisperse, water-soluble and paramagnetic magnetic nanoparticles which are easy to be modified. Firstly, magnetic silica with core-shell structure was prepared according to a previous work. Then, the magnetic silica was treated with alkali solution to afford magnetic nanoparticles. With the increase of calcination temperature for the preparation of magnetic silica, the crystallinity and the magnetic responsibility of magnetic silica strengthened, meanwhile, the corresponding magnetic nanoparticles kept monodisperse without any aggregation. The magnetic nanoparticles are comprised of cobalt ferrite and a silica coating. The silica coating on the cobalt ferrite facilitates the magnetic nanoparticles well-dissolved and monodisperse in water, and easilv modified.

Theoretical Study on Effects of Salt and Temperature on Denaturation Transition of Double-stranded DNA

We investigate the statistical mechanics properties of a nonlinear dynamics model of the denaturation of the DNA double-helix and study the effects of salt concentration and temperature on denaturation transition of DNA. The specific heat, entropy, and denaturation temperature of the system versus salt concentration are obtained. These results show that the denaturation of DNA not only depends on the temperature but also is influenced by the salt concentration in the solution of DNA, which are in agreement with experimental measurement.

Salt＇s Effect on Anatomy and Deformity of Pistacia vera Nut

This study attempts to examine the effects of salinity on leaf, stem, and nut of Pistacia vera （Ohady and Kaleh Ghochi cultivars） in order to characterize their anatomical structures with electron and light microscopy. A comparative study of the anatomy indicates a difference between the density of simple and glandular trichomes in leaf surface, deposit of wax, the thickness of leaf, the length of epidermal cells, palisade parenchyma cells, crystals in mesophyll, and the manner of compatibility to salinity. The results obtained in this research demonstrate that compatibility of Ohady cultivar is higher than Kaleh Ghochi and the degree of mechanical wounding depends on their development stages. In addition to results of previous studies which considered crop load as the main cause of fruit deformity. The present study indicates that, in spite of some reduction in total production of a tree, salinity decreases fruit deformity and to a high extent prevents the production of deformed fruit. Indeed, a remarkable reduction in production of deformed fruit will be yielded by selecting pistachio varieties which are resistant to salinity. Moreover, salinity increases the resistance of nuts to mechanical wounding. The results of this study suggest that in EC = 7.6, 12.6 deformity of nut is not related to crop load.

Gill Epithelium Ultrastructure of Oreochromis niloticus Exposed to Gradual Raised Salinity

Fish gill is a multifunctional organ with role in acid-base balance, elimination of nitrogen waste and mainly gas exchange and ion regulation. There is a high energetic coast for ionregulation in freshwater fish maintained in salt water but a raise in growing taxes was observed for some species. The freshwater Nile tilapia, Oreochromis niloticus, is widely used in aquaculture farmers and the aim of this study was to investigate the changes on the gill filaments nltrastructure in fish kept under different salinities. Alevins were obtained and transported to laboratory of studies in animal stress Federal University of Paran~. Established groups in 0%0, 16%0 and 32%0 salt water with 12 animals in each one. After 30 days of exposition, the animals were anesthetized and the second gill arches were dissected and processed for scanning and transmission electron microscopy. The mitochondrial rich cells fractional area and density in the gill epithelia were determinated. The under scanning electron microscopy （SEM） in 0%0 salinity group reveal changes in the apical ridge of mitochondrial rich cells （MRCs）. In all other groups, the observations revealed numerous crypts disposed mainly in the filament epithelia. In transmission electron microscopy （TEM） two distinct types of MRCs were observed. The data of MRCFA and density revealed in 0%0 and 16%0 values significantly elevated in comparison to 32%0. Despite these lower values, the density in the gill epithelia was higher. The main differences found between the groups revealed that fish exposed to 16%o salinity have less MRCs aperture to the environment and are less related to ion regulation process.

Folding of EK peptide and its dependence on salt concentration and pH: A computational study

In this study, we apply both palrwise AMBER03 force field and the recently developed polarized force field to study the folding process of EK peptide under various ion strength and pH conditions. The polarized force field is based on our newly proposed adaptive hydrogen bond-specific charge （AHBC） scheme. These two force fields differ only by the atomic charges. Solvent effect is described with generalized Born models （IGB5 in AMBER 10 package）. The result shows that although when applying AMBER03 charge, the helical structure is preferred, its dependence on salt concentration and pH is qualitatively wrong. While using AHBC the peptide finds its native structure within 10 ns, and then fluctuates around this folded state. Under high salt concentration or extreme pH conditions the calculated helical structure probability drops, which is in qualitative agreement with the experiment. Analysis of the atomic charges and the interaction between the donor-acceptor pair in main hydrogen bonds shows that the helical structure is stabilized when polarization effect is counted. It again shows that polarization effect is a very important improvement over traditional force field and is essential for protein folding. We also prove that the salt bridge interaction between 4-residue apart GLU and LYS residues is not critical to the stability of helical structure of EK peptide, but is merely an auxiliary factor, also in agreement with the experiment.