Influence of Selective Edge Removal and Refractory Period in a Self-Organized Critical Neuron Model

A simple model for a set of integrate-and-fire neurons based on the weighted network is introduced. By considering the neurobiological phenomenon in brain development and the difference of the synaptic strength, we construct weighted networks develop with link additions and followed by selective edge removal. The network exhibits the small-world and scale-free properties with high network efficiency. The model displays an avalanche activity on a power-law distribution. We investigate the effect of selective edge removal and the neuron refractory period on the self-organized criticality of the system.     

Developmental validation of the Yfiler Platinum PCR Amplification Kit for forensic genetic caseworks and databases

Y chromosome kits are successfully applied in cases where human biological material exists. With the development of genotyping ability, more Y chromosomal markers are needed for finer identification of male individuals and lineages. In this study, a developmental validation of a newly emerged Y chromosome kit that combines two different kinds of markers: 38 Y-STRs and 3 Y-indels are conducted. The results show that this kit has high sensitivity when there is a small amount of DNA (125 pg), more than one male (minor:major = 1:7), or a mixture of males and females (male:female = 125pg:1875pg), inhibited substances (800 μM hematin and more than 1600 ng/μL humic acid). The kit exhibits high precision level with a standard deviation of allele size no more than 0.14 nt. Locus DYS481 shows the largest stutter rate, with three stutters per true allele. Population samples are well identified (MP of 0.001106), and mutations can be observed in father–son pairs (46 mutations in 70 pairs, 10 in locus DYS627). Out of all the population samples, 13.2% belong to haplogroup M117-O2a2b1a1, with their ethnic group being Han Chinese. The results show that this kit can improve the performance of identifying male individuals, obtaining more unique haplotypes (increasing from 894 to 918 of 1000 male samples) and higher discrimination capacity (increasing from 0.942 to 0.955) in this study compared to previous widely used Yfiler Plus kit. Besides, it gives information about their paternal lineages in forensic genetic casework and genealogical database construction.     

Amplification of chirality as a pathway to biological homochirality

Amplification of enantiomeric enrichment is a key feature for the chemical evolution of biological homochirality from the origin of chirality. The aggregations of the enantiomers by diastereomeric interactions enable the modification of their enantiomeric excess during some chemical processes. Fluorine-containing chiral compounds possess large amplification effect via distillation, sublimation and achiral chromatography by self-disproportionation. Asymmetric amplifications in enantioselective catalysis occur by the differential formation and reactivity between homochiral and heterochiral aggregate in solution.We described the amplification of ee in asymmetric autocatalysis of 5-pyrimidyl alkanol in the reaction between diisopropylzinc and pyrimidine-5-carbaldehdye. During the reactions extremely low ee (ca. 0.00005% ee) can be amplified to achieve more than 99.5% ee. Since the proposed origins of chirality such as CPL, quartz, chiral organic crystals of achiral compounds and statistical fluctuation of ee can initiate the asymmetric autocatalysis with amplification of ee, the proposed origin of chirality can be linked with enantiopure organic compound in conjunction with amplification of ee by asymmetric autocatalysis. In addition, we described that the carbon isotopically chiral compound triggers the asymmetric autocatalysis of 5-pyrimiodyl alkanol to afford the enantioenriched product with the absolute configuration correlated with that of carbon isotope chirality, that is, isotope chirality including hydrogen isotopes can control the enantioselectivity of asymmetric addition of alkyl metal reagent to aldehyde.     

高功率准分子激光主振荡功率放大系统光学元件的稳定性

为了分析高功率准分子激光主振荡功率放大(MOPA)系统中各光学元件稳定性对靶面光斑定位精度的影响,建立了分析模型,利用分析结果指导高稳定性镜架设计以满足系统实验需求。根据高功率准分子激光MOPA系统特点,有效地简化了系统光路,建立了系统光路模型;按照系统打靶精度要求,利用三维坐标变换和光线追迹法,计算得到了系统单个光学元件稳定性对靶面光斑定位精度的影响规律;最后,对自行设计的镜架进行了稳定性测量。计算结果表明,反射镜的旋转变化和透镜垂直光轴的平移变化是影响靶面光斑定位精度的主要因素,且主放大光路中反射镜在X方向和Y方向上最大的变化范围分别不能超过0.8和1.6μrad。实际测量结果表明,设计的镜架在X方向和Y方向最大的变化范围分别为0.6和0.81μrad,满足系统实验要求。     

The analysis of the error statistics in a 5 × 40 Gbit/s fibre link with hybrid amplification

We quantify the error statistics and patterning effects in a 5 × 40 Gbit/s WDM RZ-OOK SMF/DCF fibre link using hybrid Raman/EDFA amplification. By extensive use of a numerical model, we determine how the error statistics change with the transmission distance. This knowledge is used as a basis for a constrained coding technique in order to improve the transmission error rate. We propose an adaptive constrained code for mitigation of the patterning effects and demonstrate that this approach can substantially reduce the bit error rate (BER) even for very large values of the channel BER (BER > 10^− 1). The proposed technique can be used in combination with forward error correction schemes (FEC) to extend the range of channel BERs that an FEC scheme is effective over.     

可见/近红外光谱分析技术快速鉴别航天育种番茄

提出了利用可见/近红外光谱技术快速无损鉴别航天育种番茄品种的方法,采用偏最小二乘法对光谱特征信息进行提取,与神经网络结合建立番茄品种的鉴别模型.该模型将提取后的主成分作为神经网络的输入,加速了神经网络的训练速度.同时采用小波变换对大量光谱数据进行压缩,并结合神经网络建立番茄品种鉴别模型,该模型将压缩后的数据作为神经网络...     

Oligo诱导突变的改进方法

介绍一种改进的Ｏｌｉｇｏ诱导ＤＮＡ定点突变方法，此法制备的含Ｕ野生型模板ＤＮＡ在ＪＭ１０７中的存活率从５％～１０％下降至１％～２％；诱变反应终产物转染ＪＭ１０７产生的斑数比原法提高１５～２０倍，诱导连续４个核苷酸替换产生的突变频率达８０％～８５％，即使诱导连续１２个核苷酸的缺失，也能获得４０％～５０％的突变频率．     

二层线性规划的自适应遗传算法

提出了一种自适应遗传算法来求解二层线性规划问题.该方法克服了难以确定合适的交叉概率和变异概率的困难.另外,在该方法中还采用了其它一些技巧不仅解决了在采用遗传算法经常出现的有些个体不可行的问题,而且还改进了算法的效率.     

Binding of singlet oxygen with a stacked guanine dimer

Geometry optimization calculations were performed using the B3LYP/6‐31+G* method on the complexes of ¹O₂ and ³O₂ molecules with a stacked dimer of planar guanine, varying the distance (D) between the planes of the guanine molecules. In this process, geometries of the guanine molecules were held fixed, D was fixed at different values, while the bond lengths of ¹O₂ and ³O₂ as well as their orientations with respect to the guanine molecules were optimized for each value of D. The complexes in their most stable geometries were solvated in water using the integral equation formalism of the polarized continuum model of the self‐consistent reaction field theory. In gas phase, the most stable complex between ¹O₂ and the guanine dimer (2G.¹O₂) is formed when D is about 6 Å, while the most stable complex between ³O₂ and the guanine dimer (2G.³O₂) is formed when D is about 3.75 Å. In the minimum total energy geometry of 2G.¹O₂, ¹O₂ is located between the guanine molecules, above the imidazole ring of one of them. However, in the minimum total energy geometry of 2G.³O₂, ³O₂ is located outside the stack of guanine molecules, near the amino group of one of them. The solvation calculations showed that in aqueous media, ¹O₂ would bind with the stacked guanine dimer more strongly than in gas phase, while ³O₂ would not bind with the same. The mode of binding of ¹O₂ with the stacked guanine dimer is such that it seems that ¹O₂ would replace one basepair in DNA, as happens in the intercalative mode of binding of drugs and other molecules, and it can lead to the formation of 8‐oxoguanine that has a mutagenic nature. © 2004 Wiley Periodicals, Inc. Int J Quantum Chem, 2005     

Signature invariants of covering links

We apply the theory of signature invariants of links in rational homology spheres to covering links of homology boundary links. From patterns and Seifert matrices of homology boundary links, we derive an explicit formula to compute signature invariants of their covering links. Using the formula, we produce fused boundary links that are positive mutants of ribbon links but are not concordant to boundary links. We also show that for any finite collection of patterns, there are homology boundary links that are not concordant to any homology boundary links admitting a pattern in the collection.