运行车速预测中的汽车换档

针对汽车行驶中,驾驶员主要根据汽车的动力性进行减速换档的实际情况,在汽车加速换档的基础上,研究了汽车进行减速换档的规律。根据驾驶员实际操作规律,提出了动力换档法,以东风EQ 140为例,确定了汽车进行减速换档时的最佳运行速度。最后给出了汽车换档的速度损失计算公式。     

Multiple D2 dopamine receptors produced by alternative RNA splicing

Dopamine receptor belong to a large class of neurotransmitter and hormone receptors that are linked to their signal transduction pathways through guanine nucleotide binding regulatory proteins (G proteins). Pharmacological, biochemical and physiological criteria have been used to define two subcategories of dopamine receptors referred to as D1 and D2. D1 receptors activate adenylyl cyclase and are coupled with the Gs regulatory protein. By contrast, activation of D2 receptors results in various responses including inhibition of adenylyl cyclase, inhibition of phosphatidylinositol turnover, increase in K+ channel activity and inhibition of Ca2+ mobilization. The G protein(s) linking the D2 receptors to these responses have not been identified, although D2 receptors have been shown to both copurify and functionally reconstitute with both Gi and Go related proteins. The diversity of responses elicited by D2-receptor activation could reflect the existence of multiple D2 receptor subtypes, the identification of which is facilitated by the recent cloning of a complementary DNA encoding a rat D2 receptor. This receptor exhibits considerable amino-acid homology with other members of the G protein-coupled receptor superfamily. Here we report the identification and cloning of a cDNA encoding an RNA splice variant of the rat D2 receptor cDNA. This cDNA codes for a receptor isoform which is predominantly expressed in the brain and contains an additional 29 amino acids in the third cytoplasmic loop, a region believed to be involved in G protein coupling.     

一种改进的无参数自组织映射算法

通过允许映射对没有被较好映射的输入作较大的调整,无参数自组织映射(PLSOM)能够快速而正确地适应新的输入范围,但是输入分布与权密度之间对应性较差.论文提出了一种基于PLSOM的改进算法.在两种不同的情况下采用两种不同的权值更新方法.一种采用修改过的PLSOM,另一种则采用改进过的SOM.实验结果表明,这种改进算法不仅能快速正确地适应新的输入范围,而且能较好地体现输入分布.     

Multi-domain conformational selection underlies pre-mRNA splicing regulation by U2AF

Many cellular functions involve multi-domain proteins, which are composed of structurally independent modules connected by flexible linkers. Although it is often well understood how a given domain recognizes a cognate oligonucleotide or peptide motif, the dynamic interaction of multiple domains in the recognition of these ligands remains to be characterized. Here we have studied the molecular mechanisms of the recognition of the 3'-splice-site-associated polypyrimidine tract RNA by the large subunit of the human U2 snRNP auxiliary factor (U2AF65) as a key early step in pre-mRNA splicing. We show that the tandem RNA recognition motif domains of U2AF65 adopt two remarkably distinct domain arrangements in the absence or presence of a strong (that is, high affinity) polypyrimidine tract. Recognition of sequence variations in the polypyrimidine tract RNA involves a population shift between these closed and open conformations. The equilibrium between the two conformations functions as a molecular rheostat that quantitatively correlates the natural variations in polypyrimidine tract nucleotide composition, length and functional strength to the efficiency to recruit U2 snRNP to the intron during spliceosome assembly. Mutations that shift the conformational equilibrium without directly affecting RNA binding modulate splicing activity accordingly. Similar mechanisms of cooperative multi-domain conformational selection may operate more generally in the recognition of degenerate nucleotide or amino acid motifs by multi-domain proteins.     

Functional complexity and regulation through RNA dynamics

Changes to the conformation of coding and non-coding RNAs form the basis of elements of genetic regulation and provide an important source of complexity, which drives many of the fundamental processes of life. Although the structure of RNA is highly flexible, the underlying dynamics of RNA are robust and are limited to transitions between the few conformations that preserve favourable base-pairing and stacking interactions. The mechanisms by which cellular processes harness the intrinsic dynamic behaviour of RNA and use it within functionally productive pathways are complex. The versatile functions and ease by which it is integrated into a wide variety of genetic circuits and biochemical pathways suggests there is a general and fundamental role for RNA dynamics in cellular processes.     

An Adaptive Non-Linear Map and Its Application

A novel adaptive non-linear mapping （ANLM）, integrating an adaptive mapping error （AME） with a chaosgenetic algorithm （CGA） including chaotic variable, was proposed to overcome the deficiencies of non-linear mapping （NLM）. The value of AME weight factor is determined according to the relative deviation square of distance between the two mapping points and the corresponding original objects distance. The larger the relative deviation square between two distances is, the larger the value of the corresponding weight factor is. Due to chaotic mapping operator, the evolutional process of CGA makes the individuals of subgenerations distributed ergodieally in the defined space and circumvents the premature of the individuals of subgenerations. The comparison results demonstrated that the whole performance of CGA is better than that of traditional genetic algorithm. Furthermore, a typical example of mapping eight-dimenslonal olive oil samples onto two-dimensional plane was employed to verify the effectiveness of ANLM. The results showed that the topology-preserving map obtained by ANLM can well represent the classification of original objects and is much better than that obtained by NLM.