Diffusion Dynamics in Interconnected Communities

In this dissertation, multi-community-based Susceptible-Infected-Recovered (SIR) and Susceptible-Infected-Susceptible (SIS) models of infection/innovation diffusion are introduced for heterogeneous social networks in which agents are viewed as belonging to one of a finite number of communities. Agents are assumed to have well-mixed interactions within and between communities. The communities are connected through a backbone graph which defines an overall network structure for the models. The models are used to determine conditions for outbreak of an initial infection. The role of the strengths of the connections between communities in the development of an outbreak as well as long-term behavior of the diffusion is also studied. Percolation theory is brought to bear on these questions as an independent approach separate from the main dynamic multi-community modeling approach of the dissertation. Results obtained using both approaches are compared and found to be in agreement in the limit of infinitely large populations in all communities. Based on the proposed models, three classes of marketing problems are formulated and studied: referral marketing, seeding marketing and dynamic marketing. It is found that referral marketing can be optimized relatively easily because the associated optimization problem can be formulated as a convex optimization. Also, both seeding marketing and dynamic marketing are shown to enjoy a useful property, namely ``continuous monotone submodularity." Based on this property, a greedy heuristic is proposed which yields solutions with approximation ratio no less than 1-1/e. Also, dynamic marketing for SIS models is reformulated into an equivalent convex optimization to obtain an optimal solution. Both cost minimization and trade-off of cost and profit are analyzed. Next, the proposed modeling framework is applied to study competition of multiple companies in marketing of similar products. Marketing of two classes of such products are considered, namely marketing of durable consumer goods (DCG) and fast-moving consumer goods (FMCG). It is shown that an epsilon-equilibrium exists in the DCG marketing game and a pure Nash equilibrium exists in the FMCG marketing game. The Price of Anarchy (PoA) in both marketing games is found to be bounded by 2. Also, it is shown that any two Nash equilibria for the FMCG marketing game agree almost everywhere, and a distributed algorithm converging to the Nash equilibrium is designed for the FMCG marketing game. Finally, a preliminary investigation is carried out to explore possible concepts of network centrality for diffusions. In a diffusion process, the centrality of a node should reflect the influence that the node has on the network over time. Among the preliminary observations in this work, it is found that when an infection does not break out, diffusion centrality is closely related to Katz centrality; when an infection does break out, diffusion centrality is closely related to eigenvector centrality

Genome cloning and genetic diversity of Apple chlorotic leaf spot virus

514-519Apple chlorotic leaf spot virus (ACLSV) with a wide distribution and variability is great threat to apple yield and quality. The systematic research on the occurrence, genetic structure and evolutionary mechanism is important for the prevention of ACLSV. In this study, 360 apple leaf samples were collected from Shanxi province and tested by RT-PCR, and the result showed that the incidence of ACLSV in Shanxi was ranged from 43.59% in Linfen to 68.18% in Wanrong. One new ACLSV isolate (shanxi14-MK368727) was collected from the positive samples, of which the genome (including the 5' and 3' ends) was 7507 bp and encoded 2536 amino acids. Compared with online database, the highest nd identity was between shanxi14 and KJ522693.1, and the lowest was shanxi14 and M58152.1. Phylogenetic analyzed based on genome showed that 25 isolated of ACLSV were divided two groups (Group I and II), which showed that was no significant correlation with geographic location. The selection pressures of POL, MP and CP were tested, the result proved the three genes were under negative selection pressure. The knowledge presented in this study will be useful in for the design of long-term, sustainable management strategies for controlling these viruses

Abnormal expression of SLIT3 induces intravillous vascularization dysplasia in ectopic pregnancy

Objective To investigate whether the morphology, capillary number, and transcriptome expression profiles of ectopic pregnancy (EP) villi differ from those of normal pregnancy (NP) villi. Methods Hematoxylin-eosin (HE) and immunohistochemistry (IHC) staining for CD31 were conducted to compare differences in morphology and capillary number between EP and NP villi. Differentially expressed (DE) miRNAs and mRNAs were determined from transcriptome sequencing of both types of villi and used to construct a miRNA–mRNA network, from which hub genes were identified. Candidate DE-miRNAs and DE-mRNAs were validated by quantitative reverse transcription (qRT)-PCR. Correlations were identified between the number of capillaries and serum beta human chorionic gonadotropin (β-HCG) levels and between the expression levels of hub genes associated with angiogenesis and β-HCG levels. Results The mean and total cross-sectional areas of placental villi were significantly increased in EP compared with NP villi. Capillary density was greatly reduced in EP villi and was positively correlated with β-HCG levels. A total of 49 DE-miRNAs and 625 DE-mRNAs were identified from the sequencing data. An integrated analysis established a miRNA–mRNA network containing 32 DE-miRNAs and 103 DE-mRNAs. Based on the validation of hub mRNAs and miRNAs in the network, a regulatory pathway involving miR-491-5p–SLIT3 was discovered, which may have a role in the development of villous capillaries. Conclusion Villus morphology, capillary number, and miRNA/mRNA expression profiles in villous tissues were aberrant in EP placentas. Specifically, SLIT3, which is regulated by miR-491-5p, may contribute to the regulation of villous angiogenesis and was established as a putative predictor of chorionic villus development, providing a basis for future research