黄河三角洲自然资源丰富、生态系统独特,其生态保护和高质量发展已上升为国家战略.在资源环境约束趋紧、生态系统退化的严峻形势下,黄河三角洲生态农牧化是实现其高质量发展的重要方式之一.为构建绿色、低碳、循环的黄河三角洲生态农牧化新模式,本研究分析了其高质量发展面临的问题,提出其发展的理念和目标.在此基础上,针对性地提出多元驱动的高质量发展策略与途径,即通过"场景驱动"以优化宏观布局,利用"种业牵动"、"牧养互动"和"装备推动"以完善产业体系,采用"强强联动"以创新协同范式,运用"政策促动"以实现整体升级,构建场景匹配的三场连通、三产融合的黄河三角洲生态农牧化发展新模式,实现机械化、智能化、数字化和体系化的协同发展.研究结果可为推动黄河三角洲生态农牧化高质量发展提供参考.

To research into the laws of Hosoya index for four leaf tree,by means of analyzing method of components in graph theory,the explicit formula of Hosoya index of four leaf tree and its sequence are solved.For general t leaf tree,by adopting the same method,the explicit formula of Hosoya index of corresponding t leaf tree and its sequence are obtained.A family of Fibonacci sequences whose initial values are not the same are discovered, which provides some scientific references for combinatorics and graph theory.

Social media has been a new platform for emotion expression of individuals or groups in recent years. Millions of textual messages are constantly being generated. People with different emotion perceptions have different reactions to the same emotional event occurring in real life. However, it is hard to measure individual's emotion perception ability in both real world and social networks. This paper deals with online individual's emotion in view of complex system theory, and explores the emotion expression mechanism behind tweets. An concept of emotion bifurcation point is defined to denote the emotion perception ability and a methodological framework is proposed to measure it. Under the fundamental integration of the recognized Chinese emotion dictionaries (25,651 words included in total after reconciliation), new-born emotion words (458 in total) trained from a Sina-weibo corpus with 17 million tweets and commonly used emoticons (298 in total) as full-scale as possible, an emotion element ontology is constructed. Experimental evaluation on several certificated figures on Sina-weibo are implemented and the obtained results illustrate the reliability and validity of the proposed method.

We perform comparisons among protein sequences based on a 3-D graphic representation of proteins [Bai and Wang, J. Biomol. Struc. Dyn., 23, 537–545 (2006)]. In detail, we make analysis of similarities among nine ATP6(ATP synthase F0 subunit 6) proteins by comparing their corresponding 3-D curves and select the geometric center and the correlation matrix from the 3-D curve, as well as a angle metric for the construction of the phylogenetic tree. In comparison with the traditional alignments of sequences, the proposed method does not require multiple alignment and conceptually and computationally it is rather simple.

In this paper, we give explicit algorithms to compute generating functions of some special sequences, based on the operations of differential operators and shift operators in the non-commutative context and Zeilberger's holonomic algorithm. It can be found that not only ordinary generating functions and exponential generating functions but also generating functions of the general form Sigma(n) a(n)(x)w(y, n) can now be computed automatically. Moreover, we generalize this approach and present explicit algorithms to compute 2-variable ordinary power series generating functions and mixed-type generating functions. As applications, various examples are given in the paper.

Originating from sequences' length difference, both k-word based methods and graphical representation approaches have uncovered biological information in their distinct ways. However, it is less likely that the mechanisms of information storage vary with sequences' length. A similarity distance suitable for sequences with various lengths will be much near to the mechanisms of information storage. In this paper, new sub-sequences of k-word were extracted from biological sequences under a one-to-one mapping. The new sub-sequences were evaluated by a linear regression model. Moreover, a new distance was defined on the invariants from the linear regression model. With comparison to other alignment-free distances, the results of four experiments demonstrated that our similarity distance was more efficient.

PbSe semiconductor nanocrystals (NCs) have attracted ever-growing interest owing to both their fundamental physics and potential applications in a diverse range of fields such as optoelectronic devices and nonlinear optics. The current fabrication strategy for colloidal PbSe NCs, however, frequently involves acutely toxic reagents and tedious reaction procedures, and is plagued by products with poorly controlled size and morphology. Herein, we report a facile, low-cost, and phosphine-free method for synthesizing PbSe NCs, which provides highly uniform NCs with tunable mid-IR absorption, and they are promising for bio-related applications. These high quality NCs were obtained by the reaction of elemental Se and PbCl2 in oleylamine as both the ligand and reaction medium. The high flexibility and reproducibility of the method reported in this study allows us to synthesize monodispersed PbSe NCs with well-controlled size and morphology. In addition, these products show strong optical limiting effects, and thus hold potential for developing nonlinear optical devices.

We describe a novel method for the local analysis of complete genomes. A local distance measure called LODIST is proposed, which is based on the relationship between the longest common words and the shortest absent words of two genomes we compared. LODIST can perform better than local alignment when the local region is large enough to cover some recombination genes. A distance measure called SILD.k.t with resolution k and step t is derived by the integral LODISTs of whole genomes. It is shown that the algorithm for computing the LODISTs and SILD. k. t is linear, which is fast enough to consider the problem of the genome comparison. We verify this method by recognizing the subtypes of the HIV-1 complete genomes and genome segments.

Numerous efficient methods based on word counts for sequence analysis have been proposed to characterize DNA sequences to help in comparison, retrieval from the databases and reconstructing evolutionary relations. However, most of them seem unrelated to any intrinsic characteristics of DNA. In this paper, we proposed a novel statistical measure for sequence comparison on the basis of k-word counts. This new measure removed the influence of sequences' lengths and uncovered bulk property of DNA sequences. The proposed measure was tested by similarity search and phylogenetic analysis. The experimental assessment demonstrated that our similarity measure was efficient.

Graphical representation of a DNA sequence is a powerful tool for basic biological research. Based on the ordered dinucleotides, we propose a novel three dimensional (3D) graphical representation without circuit or degeneracy. Simultaneously, we derive the projection curve of the 3D graph. These two curves have good visualization for longer DNA sequences. The utility of the proposed curves is illustrated by mutation analysis, similarity analysis, and evolutionary relationships of different species. The results indicate that our method is efficient and powerful. (c) 2011 Wiley Periodicals, Inc. Int J Quantum Chem, 2012

Knowledge of structural classes plays an important role in understanding protein folding patterns. In this paper, features based on the predicted secondary structure sequence and the corresponding E-H sequence are extracted. Then, an 11-dimensional feature vector is selected based on a wrapper feature selection algorithm and a support vector machine (SVM). Among the 11 selected features, 4 novel features are newly designed to model the differences between alpha/beta class and alpha + beta class, and other 7 rational features are proposed by previous researchers. To examine the performance of our method, a total of 5 datasets are used to design and test the proposed method. The results show that competitive prediction accuracies can be achieved by the proposed method compared to existing methods (SCPRED, RKS-PPSC and MODAS), and 4 new features are demonstrated essential to differentiate alpha/beta and alpha + beta classes. Standalone version of the proposed method is written in JAVA language and it can be downloaded from http://web.xidian.edu.cn/slzhang/paper.html. (C) 2012 Elsevier Masson SAS. All rights reserved.

In this paper, we propose a new similarity measure to compare RNA secondary structure. We first transform an RNA secondary structure into three characteristic sequences. Then, based on these characteristic sequences, we calculate their LZ complexity. Finally, we obtain the similarity/dissimilarity matrix based on the LZ complexity, and make a comparison for the secondary structures at the 3′-terminus belonging to nine different species. The proposed method does not require multiple alignments and is easy to operate. This method will also be useful to researchers who are interested in evolutionary analysis.

In this study, the normalized k-word average interval distance is proposed to extract phylogenetic information from DNA sequences. The phylogenetic trees of 30 mammalian species based on Euclidean distance measure are reconstructed with k ranging from 2 to 9. Comparison of our results with other methods shows that our method is efficient and powerful for phylogenetic analysis. In addition, for a fixed k, 4(k) distinct k-words are divided into n classes based on a new proposed indicator, where n is the number of DNA sequences. The effect of each k-word class on phylogeny is discussed.

In this paper, we define the self-inverse sequences related to Sheffer sets and give some interesting results of these sequences. Moreover, we study the self-inverse sequences related to the Laguerre polynomials of order alpha.

The main work of this paper is to propose a new theory and method, which is based on the idea of the pseudo-amino acid composition, for phylogenetic analysis of DNA primary sequences. In our method, we revise the part of the occurrence frequency of 20 amino acids in the method of the pseudo-amino acid composition by replacing the frequency of 16 dinucleotides. And we select eight LZ complexity factors of eight (0,1) sequences of a DNA primary sequence as PseAA components. Finally, we characterize a DNA sequence with a 24-dimensional vector. We reconstruct the phylogenetic trees of two datasets. The results show that our method is efficient and significant.