Can the occurrence of rare insertion/deletion polymorphisms in human mtDNA be verified from phylogeny?

Due to its specific characteristics, such as maternal inheritance and absence of recombination, each mtDNA belongs to certain monophyletic clade in the rooted mtDNA tree (haplogroup) according to the mutations it harbors. Rare mutation (excluding parallel mutation) occurring at multiple times in different haplogroups could thus be a potential reading error according to the mtDNA phylogeny. This experience has been widely used in double-checking the credibility of the rare mutations in human mtDNA sequences. However, no test has been performed so far for the feasibility of applying this strategy to the rare insertion/deletion (indel) events in mtDNA sequences. In this study, we attempted to relate the rare indels in mtDNAs to their haplogroup status in a total of 2352 individuals from 50 populations in China. Our results show that the insertion of A at position 16259 is restricted to a subclade of haplogroup C and can be verified. The other indel polymorphisms, which occur in the repeat of the deleted or inserted nucleotide(s), may not be distinguished from phantom mutations from a phylogenetic point of view. Independently and multiply sequencing the fragment with the indel is the best and the most reliable way for confirmation.

Lack of genetic association between the angiotensin-converting enzyme gene insertion/deletion polymorphism and longevity in a Han Chinese population

Introduction. The insertion/deletion polymorphism of the angiotensin-converting enzyme (ACE) gene has been reported to associate with human longevity. However, little information is available in a Han Chinese longevity Population. Therefore, we investigat

A miniature insertion element transposable in Microcystis sp FACHB 854

A 186-bp sequence with imperfect terminal inverted repeats and target direct repeats but without any transposase-encoding capacity was found to be transposable in an isolate derived from Microcystis sp. FACHB 854. This miniature insertion element, designated as ISM854-1, and with its homologues present at least 10 copies in the genome of Microcystis FACHB 854, is inserted into the 8-bp long and AT-rich target sequences, but none or few in other Microcystis strains. A variant of ISM854-1, denoted ISM854-1A, has perfect inverted repeat sequences and may transpose in pairs in a structure like a composite transposon. This is the first report of non-autonomous transposition of a mini-IS in a cyanobacterium.

Rearrangeable nonblocking SOI waveguide thermooptic 4x4 switch matrix with low insertion loss and fast response

A rearrangeable nonblocking 4 x 4 thermooptic silicon-on-insulator waveguide switch matrix at 1.55-mu m integrated spot size converters is designed and fabricated for the first time. The insertion losses and polarization-dependent losses of the four channels are less than 10 and 0.8 dB, respectively. The extinction ratios are larger than 20 dB. The response times are 4.6 mu s for rising edge and 1.9 mu s for failing edge.

A silicon-on-insulator-based thermo-optic waveguide switch with low insertion loss and fast response

A silicon-on-insulator-based thermo-optic waveguide switch integrated with spot size converters is designed and fabricated by inductively coupled plasma reactive ion etching. The device shows good characteristics, including low, insertion loss of 8 +/- 1 dB for wavelength 1530-1580 nm and fast response times of 4.6 As for rising edge and 1.9 mu s for failing edge. The extinction ratios of the two channels are 19.1 and 18 dB, respectively.

Influence of GaAsP insertion layers on performance of InGaAsP/InGaP/AlGaAs quantum-well laser

We report on the use of very thin GaAsP insertion layers to improve the performance of an InGaAsP/InGaP/AlGaAs single quantum-well laser structure grown by metal organic chemical vapour deposition. Compared to the non-insertion structure, the full width at half maximum of photoluminescence spectrum of the insertion structure measured at room temperature is decreased from 47 to 38 nm indicating sharper interfaces. X-ray diffraction shows that the GaAsP insertion layers between AlGaAs and InGaP compensates for the compressive strain to improve the total interface. The laser performance of the insertion structure is significantly improved as compared with the counterpart without the insertion layers. The threshold current is decreased from 560 to 450mA while the slope efficiency is increased from 0.61 to 0.7W/A and the output power is increased from 370 to 940mW. The slope efficiency improved is very high for the devices without coated facets. The improved laser performance is attributed to the suppression of indium carry-over due to the use of the GaAsP insertion layers.

Electron resonant tunneling through InAs/GaAs quantum dots embedded in a Schottky diode with an AlAs insertion layer

Molecular beam epitaxy was employed to manufacture self-assembled InAs/GaAs quantum dot Schottky resonant tunneling diodes. By virtue of a thin AlAs insertion barrier, the thermal current was effectively reduced and electron resonant tunneling through quantum dots under both forward and reverse biased conditions was observed at relatively high temperature of 77 K. The ground states of quantum dots were found to be at similar to 0.19 eV below the conduction band of GaAs matrix. The theoretical computations were in conformity with experimental data. (c) 2006 The Electrochemical Society.

Wavelength tuning in GaAsAlGaAs quantum wells by InAs submonolayer insertion

Wavelength tuning of exciton emissions has been achieved simply by inserting an InAs submonolayer at the centre of GaAs quantum wells during molecular beam epitaxy growth. Photoluminescence measurements show that the emission energy can be effectively tuned from the quantum-well-determined energy down to less than the band gap of GaAs, depending on the well width as well as the InAs layer thickness. Using the effective-mass approximation, the tuning effect can be well predicted theoretically The results reported here may provide an alternative way to tune the wavelength in optoelectronic devices.

SYNTHESIS AND CRYSTAL-STRUCTURES OF THE BIMETALLIC RARE-EARTH COMPLEXES AND STUDIES ON INSERTION MECHANISM OF DIENES POLYMERIZATION

The deepening of the studies on essentials of rare earth coordination catalyst brings about more and more reports on model compounds as active centre of the catalyst. Among them the most significant researches are those with identification of the crystal structures of compounds.

快速Delaunay逐点插入网格生成算法

对插入形心的Delaunay逐点插入算法,提出按单元可插度分组的双向链表组数据结构,避免了对最大可插度单元的搜索。采用了邻接单元搜索、双向链表存储、随机方向搜索、邻接旋转、几何量继承等技术,使算法的计算时间与生成单元数近似呈线性关系,时间复杂度达到O(N1.05),N为生成单元数。算例表明,在一台AMD Athlon3200+(主频2.0 GHz)PC上,该算法的四面体单元生成速度达50 000个/s以上。

一种闭环控制的光纤光栅动态色散补偿仪

利用啁啾光纤光栅的应变调谐特性，将色散补偿的啁啾光纤光栅斜贴于悬臂梁的侧面，通过应力实现啁啾量调整而改变其色散补偿量的大小，同时利用固定在同一悬臂梁的均匀布拉格光栅传感器，实现了闭环自动控制色散补偿量，研制出了一种新型的光纤光栅动态色散补偿仪。该色散补偿仪工作在1550nm波段，典型性能数据为：色散动态补偿范围-1000-1680ps／nm，插入损耗小于1．5dB，动态调谐步进响应时间小于50ms，基本上能满足10Gb／s光纤通信系统中色散动态补偿的要求。

基于达曼光栅的动态光耦合器

提出了一种基于达曼光栅的动态光耦合器,通过控制装置中达曼光栅位移参量,可实现入射光束的分束或合束以及两者之间的动态转换。适当选择达曼光栅类型可实现任意N×M的动态光耦合。实验中以1550 nm光波长为例,对1×8达曼动态光耦合器进行测量,测得其实现光开关功能时插入损耗为0.43 dB,实现光分束功能时均匀性达到0.03,单路插入损耗均值为10.5 dB。该实验装置易于调节、体积小、能耗低,且关键元件达曼光栅制作工艺成熟,易于批量化生产。特别是在实现中大规模光交换阵列时,该方案就具有更明显的优越性,有实用意