基于朴素基因表达式编程挖掘紧致函数

基因表达式编程(GEP)是一种基因型和表现型相分离的进化新模型,为了挖掘紧致的函数关系,分析了进化系统各因素对挖掘紧致函数的影响,提出了带紧致压力的适应度函数来进化函数紧致解。实验表明,带有紧致压力的适应度函数能自动进化计算机程序,适合挖掘的紧致关系,在挖掘紧致函数中,朴素基因表达式编程(NGEP)比GEP提高效率21.7%,与不带压力的系统相比,GEP的平均压缩了31.2%,NGEP系统平均压缩了42.5%;NGEP较GEP更容易发现紧致解,且函数表达形式更容易理解,丰富了NGEP理论.     

非平稳噪声下稀疏表示的DOA估计算法

为提高非平稳噪声下远场非相干窄带信号波达方向（DOA）的估计精度,提出了一种基于稀疏重构的DOA估计算法.采用类协方差差分算法构造差分矩阵,抑制非平稳噪声的影响;基于类旋转不变子空间参数估计算法基本原理构造稀疏表示模型与权函数;利用加权l₁范数对模型求解,实现DOA估计.仿真结果表明,与传统的协方差差分算法、噪声协方差矩阵估计算法、秩迹最小化算法以及稀疏重构算法相比,所提算法不仅能较好地抑制非平稳噪声的影响,而且在低信噪比、低快拍数情况下具有较强的稳健性和较高的估计精度.     

基于多Agent的多型号生产调度系统研究

生产调度系统是多型号产品生产中的关键环节.为适应军工生产企业对生产调度系统的新要求,提出了基于多智能体技术,构筑多型号生产调度系统.首先,给出了多型号产品生产计划调度运行模式;然后,建立了基于多智能体的多型号生产调度系统模型,设计了相应的智能体的模型结构.为了解决调度冲突,将智能体之间的协商过程分为主控协商和自主协商2级协商,并给出了协商机制和相应的算法策略.最后,给出了基于Web环境的系统实现体系结构.     

Activation of Polycyclic Aromatic Compounds by cDNA-Expressed Phase I and Phase II Enzymes

A large number of human and other mammalian xenobiotic-metabolizing enzymes have been expressed in target cells of standard mutagenicity tests, such as Ames's Salmonella typhimurium strains and Chinese hamster V79 cells. These recombinant cells are useful for determining the ability of individual enzymes to activate (or inactivate) a given compound. In contrast to standard S9-mediated test systems, they also allow the detection of mutagenic metabolites that do not penetrate cell membranes--a situation often found with reactive phase II metabolites. We present mutagenicity data for benzo[ a ]pyrene and dibenzo[ a,l ]pyrene in V79-derived cells expressing human cytochrome P450 (CYP) 1A1, 1A2, and 1B1, and for 1-hydroxymethylpyrene, R - and S -1-( f -hydroxyethyl) pyrene, 4-hydroxycyclopenta[ def ]chrysene and N -hydroxy-2-acetylaminofluorene in V79-derived cells and/or Salmonella strains expressing the 11 human sulfotransferases (SULTs) identified. In some cases, allelic variants and orthologous enzymes from other mammalian species were also investigated. The data indicate that mutagenicity of many compounds is detected in the appropriate recombinant systems at extremely low substrate concentrations, that the activation of various promutagens is mediated with high specificity by only one or few enzyme forms, and that substantial differences may occur between alloenzymes from the same species and orthologous enzymes from different species. Such information could be important for understanding differences in susceptibility between tissues, species, individual genetic traits, and physiological states.     

Responses of Human Cells to PAH-Induced DNA Damage

Benzo[ a ]pyrene (B[ a ]P) and dibenzo[ a,l ]pyrene (DB[ a,l ]P) induce cytochrome P450 (CYP) CYP1A1 and CYP1B1, which metabolize these polycyclic aromatic hydrocarbons (PAHs) into DNA-binding species. In order to detail roles of CYP1A1 and CYP1B1 in activation of DB[ a,l ]P to the diol epoxide, we here report the inhibition of CYP1A1 in human MCF-7 cells with phosphorodiamidate morpholino antisense oligomers (morpholinos). PAH-DNA adduct formation was also determined after treatment with morpholinos and B[ a ]P or DB[ a,l ]P. p53 is involved in DNA repair, cell cycle arrest, and apoptosis. Cells with normal p53 protein arrest in the G1 phase of the cell cycle on exposure to DNA-damaging agents (presumably allowing the cell sufficient time to repair damaged DNA prior to replication). Previous studies in human MCF-7 cells indicate that cells with PAH-DNA adducts escape cell cycle arrest and accumulate in the S phase. In the present study the effect of PAH-DNA adducts on the cell cycle were observed in human diploid fibroblasts (HDF). We found that treatment of HDF with the diol epoxide of DB[ a,l ]P causes cell cycle arrest in G 1 . An increase in DNA adduct formation with increase in concentration of dibenzo[ a,l ]pyrene diol epoxide {( m )- anti -DB[ a,l ]PDE} was also observed.     

Synthesis and characterisation of fluorescent pyrene‐end‐capped polylactide fibres

Fluorescent markers are critical for tracking the position and movement of molecules both <i>in vivo</i> and <i>in vitro</i>. Conventionally, synthetic dyes are non‐covalently added to polymers for fluorescent tracking, but often diffuse away. Here we demonstrate, for the first time, a facile method for the synthesis of fluorescent poly(lactic acid) nano‐/microfibres for biomedical applications using solution spin blowing. Pyrene‐end‐capped poly(l ‐lactide) (PLLA) derivatives were synthesised using the ring‐opening polymerisation of l ‐lactide and they were characterised using spectroscopic and thermal analyses. Submicrometre‐sized fluorescent fibres were produced from these PLLA derivatives using solution blow spinning techniques generating polymer blends and core–shell fibres. Such system could be further exploited to incorporate electrically conductive carbon allotropes via the pyrene aromaticity, producing fluorescent and electrically active fibres for <i>in vitro</i> monitoring and electrical stimulation. © 2018 Society of Chemical Industry     

Influence of α′‐/α‐crystal polymorphism on properties of poly(l‐lactic acid)

Poly(l ‐lactic acid) (PLLA) is a biodegradable and biocompatible thermoplastic polyester produced from renewable sources, widely used for biomedical devices, in food packaging and in agriculture. It is a semicrystalline polymer, and as such its properties are strongly affected by the developed semicrystalline morphology. As a function of the crystallization temperature, PLLA can form different crystal modifications, namely α′‐crystals below about 120 °C and α‐crystals at higher temperatures. The α′ modification is therefore of special importance as it may be the preferred polymorph developing at processing‐relevant conditions. It is a metastable modification which typically transforms into the more stable α‐crystals on annealing at elevated temperature. The structure, kinetics of formation and thermodynamics of α′‐ and α‐crystals of PLLA are reviewed in this contribution, together with the effect of α′‐/α‐crystal polymorphism on the properties of PLLA. © 2018 Society of Chemical Industry     

Influence of aliphatic polycarbonate middle block on mechanical and microstructural behaviour of triblock copolymers based on poly(l‐lactide) and polycarbonate

Three different ABA‐type triblock copolymers each containing biodegradable aliphatic polycarbonate as the middle block and poly(l ‐lactide) as the outer blocks were synthesized and the influence of the methylene chain length of the aliphatic polycarbonate middle block on various properties of the triblock copolymers was evaluated. Differential scanning calorimetry and wide‐angle X‐ray diffraction studies revealed that the incorporation of the outer blocks reduced the crystallinity of the middle aliphatic polycarbonate block. Variation of methylene chain length of the middle block led to a change in morphology from spherical to cylindrical as evidenced from atomic force microscopy studies. In addition, the mechanical properties of the block copolymers showed semi‐ductile to quasi‐brittle behaviour depending upon the composition of the middle block which was also confirmed using scanning electron microscopy. Dynamic mechanical analysis of the triblock copolymers indicated that storage modulus increased with a decrease in methylene chain length. © 2018 Society of Chemical Industry     

基于近似l0范数的稳健稀疏重构算法

针对测量值受噪声污染的稀疏重构问题,本文提出了稳健近似l0范数最小化算法.该算法首先利用反正切函数近似l0范数,然后建立基于近似l0范数的含噪稀疏重构模型,最后通过拟牛顿法求解该模型,并分析了算法的收敛性.数值仿真表明,本文提出的算法重构稀疏向量时需要较少的测量值,且具有较高的计算精度.     

l‐Citrulline Supplementation‐Increased Skeletal Muscle PGC‐1α Expression Is Associated with Exercise Performance and Increased Skeletal Muscle Weight

<section class="article-section__content" id="mnfr3251-sec-0010"> <h3> Scope</h3> l ‐citrulline has recently been reported as a more effective supplement for promoting intracellular nitric oxide (NO) production compared to l ‐arginine. Here, the effect of l ‐citrulline on skeletal muscle and its influence on exercise performance were investigated. The underlying mechanism of its effect, specifically on the expression of skeletal muscle peroxisome proliferator‐activated receptor‐gamma coactivator‐1α (PGC‐1α), was also elucidated. </section> <section class="article-section__content" id="mnfr3251-sec-0020"> <h3> Methods and results</h3> Six‐week‐old ICR mice were orally supplemented with l ‐citrulline (250 mg kg<sup>?1</sup>) daily, and their performance in weight‐loaded swimming exercise every other day for 15 days, was evaluated. In addition, mice muscles were weighed and evaluated for the expression of PGC‐1α and PGC‐1α‐regulated genes. Mice orally supplemented with l ‐citrulline had significantly higher gastrocnemius and biceps femoris muscle mass. Although not statistically significant, l ‐citrulline prolonged the swimming time to exhaustion. PGC‐1α upregulation was associated with vascular endothelial growth factor α (<i>VEGFα</i>) and insulin‐like growth factor 1 (<i>IGF‐1</i>) upregulation. <i>VEGFα</i> and <i>IGF‐1</i> are important for angiogenesis and muscle growth, respectively, and are regulated by PGC‐1α. Treatment with NG‐nitro‐l ‐arginine methyl ester hydrochloride (l ‐NAME), a nitric oxide synthesis inhibitor, suppressed the l ‐citrulline‐induced <i>PGC‐1α</i> upregulation in vitro. </section> <section class="article-section__content" id="mnfr3251-sec-0030"> <h3> Conclusion</h3> Supplementation with l ‐citrulline upregulates skeletal muscle PGC‐1α levels resulting in higher skeletal muscle weight that improves time to exhaustion during exercise. </section>