衰落性AWGN 信道的OFDM 性能保护间隔的优化(英)

阐述了OFDM系统的基本原理及保护间隔（GI）对系统的影响.首先就保护间隔（GI）参数在接收机干扰问题上起到的作用进行了讨论.然后计算了保护间隔参数的最佳值，结果表明它们对最大延迟有很强的依赖性.同时对多径衰落和加性高斯白噪声同时存在的QPSK调制情况进行了仿真，从而分别得出了GI、信噪比（SNR）、最大传播延迟和副载波数量与误码率的关系.     

Structural basis of protein phosphatase 1 regulation

The coordinated and reciprocal action of serine/threonine (Ser/Thr) protein kinases and phosphatases produces transient phosphorylation, a fundamental regulatory mechanism for many biological processes. The human genome encodes a far greater number of Ser/Thr protein kinases than of phosphatases. Protein phosphatase 1 (PP1), in particular, is ubiquitously distributed and regulates a broad range of cellular functions, including glycogen metabolism, cell-cycle progression and muscle relaxation. PP1 has evolved effective catalytic machinery but lacks substrate specificity. Substrate specificity is conferred upon PP1 through interactions with a large number of regulatory subunits. The regulatory subunits are generally unrelated, but most possess the RVxF motif, a canonical PP1-binding sequence. Here we reveal the crystal structure at 2.7 A resolution of the complex between PP1 and a 34-kDa N-terminal domain of the myosin phosphatase targeting subunit MYPT1. MYPT1 is the protein that regulates PP1 function in smooth muscle relaxation. Structural elements amino- and carboxy-terminal to the RVxF motif of MYPT1 are positioned in a way that leads to a pronounced reshaping of the catalytic cleft of PP1, contributing to the increased myosin specificity of this complex. The structure has general implications for the control of PP1 activity by other regulatory subunits.     

On a General Transformation Making a Dissimilarity Matrix Euclidean

When a dissimilarity matrix cannot be represented in a Euclidean space, it is possible to make it Euclidean by means of suitable transformations of the original dissimilarity values. In this paper we discuss some interesting properties of a class of transformations based on adding a specific squared Euclidean distance to the initial dissimilarity. An erratum to this article is available at .     

Hydrological and mechanical properties of plants to predict suitable legume species for reinforcing soil

Plants have considerable hydrological and mechanical impacts on soil. However, there are lack of documentation and limited understanding on the hydro- logical and mechanical impacts of tropical legume trees. Therefore, this study was aimed to investigate the hydro- logical and mechanical properties of three selected legume plants, Leucaena leucocephala, Adenanthera pavonina and Peltophorum pterocarpum. Regarding hydrological aspect, the study results indicated that soil on which the L. leu- cocephala was grown had the highest transpiration rate, water absorption rate （WAR） and soil matric suction （SMS）. In terms of mechanical characteristics, L. leuco- cephala exhibited the highest root tensile strength and cellulosic components in the root. Interestingly, L. leuco- cephala also showed a higher root biomass, root length and fine roots than A. pavonina and P. pterocarpum. The leaf area index （LAI） strongly correlated with SMS （R2 = 0.74）, indicating that high LAI improved SMS. The high root tensile strength and fine roots of L. leucocephala make this species special for growing as a soil reinforcing plant. Overall results suggested that L. leucocephala exhibited outstanding hydrological and mechanical prop- erties and can be a potential plant for the soil reinforcement program.     

Signalling pathways involved in ribonuclease-7 expression

Antimicrobial peptides are host defence molecules that play a potential role in preventing infection at the epithelial surfaces. Ribonuclease (RNase)-7 has been shown to possess a broad spectrum of microbicidal activity against various pathogens. Here, we demonstrate that RNase-7 protein is localised to the superficial layers of ocular surface cells and increased in response to interleukin (IL)-1β, suggesting an active role during inflammation related to ocular surface infection. Signal transduction pathways involved in RNase-7 expression are unknown. Involvement of transforming growth factor β-activated kinase-1 (TAK-1) activated nuclear factor kappa B (NF-κB) and mitogen-activated protein kinase (MAPK) pathway molecules [c-Jun N-terminal kinase (JNK), extracellular signal-regulated kinase (ERK) and p38] were studied because of their importance in infection and inflammation. Blocking the MAPKs resulted in inhibition of RNase-7 expression in response to IL-1β. However, RNase-7 induction by IL-1β was not affected by inhibiting the NF-κB signalling pathway. In conclusion, our results indicate that RNase-7 expression is specifically mediated via MAPKs but not NF-κB signalling pathways.     

分支方法与广义CH方程的显式周期波解

用动力系统分支方法和数值模拟的方法去寻找广义CH方程的显式周期波解,首先建立与非线性偏微分方程对应的平面系统,其次绘制出该系统的的分支相图并做计算机数值模拟,确定分支相图中与显式周期波解有关的特殊轨道,最后通过这种特殊轨道及椭圆函数、椭圆积分来获得显式周期波解.     

烷基三甲基溴化铵-十二烷基硫酸钠混合体系双水相性质

对正离子表面活性剂烷基三甲基溴化铵(DeTAB、DoTAB、TTAB和CTAB)和负离子表面活性剂十二烷基硫酸钠(SDS)混合体系双水相性质进行了研究.结果表明:313 K下各体系都能形成双水相,且阴、阳离子表面活性剂分别决定着阴、阳离子双水相(ATPSa、ATPSc)的性质.双水相区域中两表面活性剂的配比可能与该区域内富舍表面活性剂胶团化性能有关.胶团化越强,其在双水相中所占的比例越大.实验结果也表明:混合溶液中两表面活性剂链长的匹配扩大了双水相区域的面积,使双水相具有更好的稳定性.