Approximate Closest Community Search in Networks

Recently, there has been significant interest in the study of the community search problem in social and information networks: given one or more query nodes, find densely connected communities containing the query nodes. However, most existing studies do not address the "free rider" issue, that is, nodes far away from query nodes and irrelevant to them are included in the detected community. Some state-of-the-art models have attempted to address this issue, but not only are their formulated problems NP-hard, they do not admit any approximations without restrictive assumptions, which may not always hold in practice. In this paper, given an undirected graph G and a set of query nodes Q, we study community search using the k-truss based community model. We formulate our problem of finding a closest truss community (CTC), as finding a connected k-truss subgraph with the largest k that contains Q, and has the minimum diameter among such subgraphs. We prove this problem is NP-hard. Furthermore, it is NP-hard to approximate the problem within a factor $(2-\varepsilon)$, for any $\varepsilon >0$. However, we develop a greedy algorithmic framework, which first finds a CTC containing Q, and then iteratively removes the furthest nodes from Q, from the graph. The method achieves 2-approximation to the optimal solution. To further improve the efficiency, we make use of a compact truss index and develop efficient algorithms for k-truss identification and maintenance as nodes get eliminated. In addition, using bulk deletion optimization and local exploration strategies, we propose two more efficient algorithms. One of them trades some approximation quality for efficiency while the other is a very efficient heuristic. Extensive experiments on 6 real-world networks show the effectiveness and efficiency of our community model and search algorithms

Travel and Online Review Behavior

Understanding the generation of online reviews is a fundamental issue for firms to gain benefits from online reviews. Our study tries to investigate the antecedents of online review characteristics by figuring out the following two research questions: (1) Will travel influence consumers’ post-consumption behavior (i.e., consumers’ review behavior)? And if so, (2) will consumers’ social capital moderate the influence of travel on consumers’ review behavior? The results show that consumers on travel tend to give higher review ratings and are more possible to post pictures while writing online reviews; consumers’ social capital level exacerbates the positive influence of travel on review ratings and mitigates the positive impact of travel on review richness

Association of MTHFR polymorphisms with nsCL/P in Chinese Uyghur population

AbstractBackgroundnsCL/P (nonsyndromic cleft lip with or without cleft palate) is a complex disorder with a multifactorial etiology that involves both genetic and environmental factors. A number of studies identified that MTHFR (methylenetetrahydrofolate reductase) was associated with nsCL/P in different populations.AimIn this study, we aim to investigate the association between the polymorphism in MTHFR gene (rs1801131, rs1801133) and nsCL/P in Chinese Uyghur population.Subjects and methodsWe conducted a case–control study comparing 120 nsCL/P patients to 100 controls. The distribution of MTHFR genotypes and frequency of alleles were compared between patients and controls by chi-square test. The odds ratios (OR) and corresponding 95% confidence intervals (95% CIs) were calculated to estimate the strength of association of MTHFR gene (C677T and A1298C).ResultsFor rs1801131, allele C frequency was higher in cases than in controls (30.4%>19.0%), and the difference was statistically significant (χ2=7.538, P=0.006). The genotype distribution at rs1801131 was different between cases (AC>AA>CC, 49.2%>45.0%>5.8%) and controls (AA>AC>CC, 65.0%>32.0%>3.0%), and the difference was statistically significant (χ2=8.883, P=0.012). AC genotype was found to increase the susceptibility of nsCL/P (OR=2.219, 95% CI=1.266–3.892, P=0.005). No association was found between rs1801133 and nsCL/P.ConclusionThis study indicated that rs1801131 polymorphism in MTHFR was associated with nsCL/P in Chinese Uyghur population. Given the unique genetic and environmental characters of the Uyghur population, these findings may be helpful for exploring the pathogenesis of this complex disease

APPLICATIONS OF “THREE-THREADS-MEASURING-SYSTEM” IN THE SWIMMING FLUME

The purpose of this study was to describe the measurement principles of “three-threads-measuring-system” and its applications. 2 figures show exemplary time histories for 3D velocity during freestyle and breaststroke swimming. More detail parameters can be calculated by a self-developed software. Major parameters, including Max velocity, Min velocity, velocity variation, stroke frequency, distance per stroke, are averaged over 10 stroke cycles. Results indicate: 1)freestyle and breaststroke show different cycle characteristics in the 3D velocity curves; 2)velocity fluctuation(y direction) can be used to determine swimmer’s technique characteristics in freestyle