Effects of atmosphere visibility on performances of non-line-of-sight ultraviolet communication systems

Dependence of performances of non-line-of-sight (NLOS) solar-blind ultraviolet (UV) communication systems on atmosphere visibility is investigated numerically by correlating the propagation of UV radiation with the visibility. A simplified solar-blind UV atmospheric propagation model is introduced, and the NLOS UV communication system model is constituted based on the single scattering assumption. Using the model, numerical simulation is conducted for two typical geometry configurations and different modulation formats. The results indicate that the performance of the NLOS UV communication system is insensitive to variation of visibility in quite a large range, and deteriorates significantly only in very low-visibility weather, and is also dependent on the geometry configuration of the system. The results also show that the pulse position modulation (PPM) is preferable due to its high-power efficiency to improve the system performance. (c) 2007 Elsevier GmbH. All rights reserved.

Different protein tyrosine phosphatase superfamilies resulting from different gene reading frames

Protein tyrosine phosphatases (PTPs) are comprised of two superfamilies, the phosphatase I superfamily containing a single low-molecular-weight PTP (lmwPTP) family and the phosphatase II superfamily including both the higher-molecular-weight PTP (hmwPTP) and the dual-specificity phosphatase (DSP) families. The phosphatase I and H superfamilies are often considered to be the result of convergent evolution. The PTP sequence and structure analyses indicate that lmwPTPs, hmwPTPs, and DSPs share similar structures, functions, and a common signature motif, although they have low sequence identities and a different order of active sites in sequence or a circular permutation. The results of this work suggest that lmwPTPs and hmwPTPs/DSPs are remotely related in evolution. The earliest ancestral gene of PTPs could be from a short fragment containing about 90similar to120 nucleotides or 30similar to40 residues; however, a probable full PTP ancestral gene contained one transcript unit with two lmwPTP genes. All three PTP families may have resulted from a common ancestral gene by a series of duplications, fusions, and circular permutations. The circular permutation in PTPs is caused by a reading frame difference, which is similar to that in DNA methyltransferases. Nevertheless, the evolutionary mechanism of circular permutation in PTP genes seems to be more complicated than that in DNA methyltransferase genes. Both mechanisms in PTPs and DNA methyltransferases can be used to explain how some protein families and superfamilies came to be formed by circular permutations during molecular evolution.

Differential cognitive responses to guqin music and piano music in Chinese subjects: an event-related potential study

目的 研究古琴(一种古老的中国乐器)和钢琴音乐对认知的影响.方法 记录和分析了中国被试在两种音乐背景(古琴音乐,钢琴音乐)下完成听觉oddball任务的行为和事件相关电位(event-related potential,ERP)数据.结果 中国被试在本土文化的音乐环境(古琴音乐)下,前额区诱导出更大的P300,这一结果和已有的相关研究是相符的.同时,不同音乐背景对ERP产生的影响在N1和LPC(包括P300和P500)上也表现出差别:中国被试在古琴音乐背景下比钢琴音乐背景下表现出更多的右前侧颞叶的参与.结论 因为古琴音乐的五声调式和汉语发音的音调具有对应关系,因此我们推断在古琴音乐下所表现出的这种特性与被试的汉语环境有关.

Crossmodal effects of Guqin and piano music on selective attention: An event-related potential study

To compare the effects of music from different cultural environments (Guqin: Chinese music; piano: Western music) on crossmodal selective attention, behavioral and event-related potential (ERP) data in a standard two-stimulus visual oddball task were reco

Crossmodal effects of Guqin and piano music on selective attention: An event-related potential study (vol 466, pg 21, 2009)

Special thanks to Christopher Blair and Mumtaz Baig for their suggestions. This work was supported by National Basic Research Program of China (973 Program, 2007CB411600), National Natural Science Foundation of China (30621092), and Bureau of Science and Technology of Yunnan Province.