Internet data packet transport: from global topology to local queueing dynamics

We study structural feature and evolution of the Internet at the autonomous systems level. Extracting relevant parameters for the growth dynamics of the Internet topology, we construct a toy model for the Internet evolution, which includes the ingredients of multiplicative stochastic evolution of nodes and edges and adaptive rewiring of edges. The model reproduces successfully structural features of the Internet at a fundamental level. We also introduce a quantity called the load as the capacity of node needed for handling the communication traffic and study its time-dependent behavior at the hubs across years. The load at hub increases with network size $N$ as $\sim N^{1.8}$. Finally, we study data packet traffic in the microscopic scale. The average delay time of data packets in a queueing system is calculated, in particular, when the number of arrival channels is scale-free. We show that when the number of arriving data packets follows a power law distribution, $\sim n^{-\lambda}$, the queue length distribution decays as $n^{1-\lambda}$ and the average delay time at the hub diverges as $\sim N^{(3-\lambda)/(\gamma-1)}$ in the $N \to \infty$ limit when $2 < \lambda < 3$, $\gamma$ being the network degree exponent.Comment: 5 pages, 4 figures, submitted to International Journal of Bifurcation and Chao

Phage ϕC2 mediates transduction of Tn6215, encoding erythromycin resistance, between Clostridium difficile strains

UNLABELLED: In this work, we show that Clostridium difficile phage ϕC2 transduces erm(B), which confers erythromycin resistance, from a donor to a recipient strain at a frequency of 10(-6) per PFU. The transductants were lysogenic for ϕC2 and contained the erm(B) gene in a novel transposon, Tn6215. This element is 13,008 bp in length and contains 17 putative open reading frames (ORFs). It could also be transferred at a lower frequency by filter mating. IMPORTANCE: Clostridium difficile is a major human pathogen that causes diarrhea that can be persistent and difficult to resolve using antibiotics. C. difficile is potentially zoonotic and has been detected in animals, food, and environmental samples. C. difficile genomes contain large portions of horizontally acquired genetic elements. The conjugative elements have been reasonably well studied, but transduction has not yet been demonstrated. Here, we show for the first time transduction as a mechanism for the transfer of a novel genetic element in C. difficile. Transduction may also be a useful tool for the genetic manipulation of C. difficile.Peer reviewe

Impact of dentine hypersensitivity on oral health-related quality of life in individuals receiving supportive periodontal care

AIM: To determine the prevalence and impact of dentine hypersensitivity (DH) on oral health-related quality of life (OHRQoL) in individuals receiving supportive periodontal care (SPC). MATERIALS AND METHODS: One hundred and two adults receiving SPC were recruited for a cross-sectional study. Subjects were categorized into those who self-reported DH (DH1) or did not (DH0). Impact of DH on OHRQoL was assessed using the Chinese Condition-Specific Oral Impact on Daily Performance questionnaire (CS-OIDP). Evaluation of DH included tactile-stimulation followed by air-blast, and recorded using a Visual Analogue Scale (VAS). RESULTS: Sixty-one (59.8%) subjects self-reported DH with mean air-blast VAS score of 29.4 ± 21.3 mm and mean tactile-stimulation VAS score of 10.9 ± 14.7 mm. Fifty (49%) subjects reported impact on OHRQoL (mean CS-OIDP score = 4.7 ± 6.3). The most affected performance was cleaning the mouth (35.3%). Positive expression of DH and worse OHRQoL were associated with higher air-blast and tactile-stimulation VAS scores, and use of desensitizing agents. The minimally important difference (MID) in CS-OIDP scores was 2.0 points. Approximately 30% of the subjects reported CS-OIDP scores above the MID. CONCLUSIONS: Dentine hypersensitivity affects OHRQoL in patients undergoing SPC. The extent of impact was associated with severity of DH. © 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.postprin

Quantification of a novel biotrophic mycoparasitic fungus using genus specific real-time PCR for biocontrol of phytopathogenic Fusarium graminearum in wheat root under controlled conditions

Non-Peer ReviewedFusarium species are well-known causal agents of Fusarium root-rot, Fusarium head blight (FHB), and Fusarium damaged kernels (FDK) diseases in Saskatchewan and other provinces of Canada. Our goal is to develop quantitative real-time PCR techniques to determine and evaluate interactions between Fusarium-associated biotrophic mycoparasitic fungus SMCD 2220 and 3-acetyldeoxynivalenol (3-ADON) producing Fusarium graminearum Schwabe – in and surrounding wheat roots. ITS1F/ITS4 (internal transcribed spacer) sequences from SMCD 2220 biotrophic mycoparasitic fungal isolate and 20 different Fusarium strains were aligned, and consensus sequences were verified. Four candidate primer sets from ITS regions were designed based on the non-conserved regions of the consensus sequences. Using the primer set SmyITSF/R, the biotrophic mycoparasite genomic DNAs were amplified from SMCD 2220. This primer set was developed for assessing and quantifying the interactions between SMCD 2220 biotrophic mycoparasite and F. graminearum. Well-known necrotrophic T. harzianum T-22, was used as the positive control. During in vitro studies, only SMCD 2220 was observed to improve wheat seed germination, whereas T-22 induced post-emergence damping-off symptoms. Under controlled phytotron conditions, both SMCD 2220 and T. harzianum strains were able to reduce the quantity of F. graminearum in spring wheat root, as well as improving the survival and growth of the spring wheat seedlings. However, amount of SMCD 2220 DNA detected was no significantly difference between wheat inoculated with F. graminearum and without Fusarium. In contrary, the amount of T. harzianum DNA monitored in the treatment inoculated with F. graminearum was observed to reduce significantly, as compared to non-Fusarium treatment

Nonlocal evolution of weighted scale-free networks

We introduce the notion of globally updating evolution for a class of weighted networks, in which the weight of a link is characterized by the amount of data packet transport flowing through it. By noting that the packet transport over the network is determined nonlocally, this approach can explain the generic nonlinear scaling between the strength and the degree of a node. We demonstrate by a simple model that the strength-driven evolution scheme recently introduced can be generalized to a nonlinear preferential attachment rule, generating the power-law behaviors in degree and in strength simultaneously.Comment: 4 pages, 4 figures, final version published in PR

Sandpiles on multiplex networks

We introduce the sandpile model on multiplex networks with more than one type of edge and investigate its scaling and dynamical behaviors. We find that the introduction of multiplexity does not alter the scaling behavior of avalanche dynamics; the system is critical with an asymptotic power-law avalanche size distribution with an exponent $\tau = 3/2$ on duplex random networks. The detailed cascade dynamics, however, is affected by the multiplex coupling. For example, higher-degree nodes such as hubs in scale-free networks fail more often in the multiplex dynamics than in the simplex network counterpart in which different types of edges are simply aggregated. Our results suggest that multiplex modeling would be necessary in order to gain a better understanding of cascading failure phenomena of real-world multiplex complex systems, such as the global economic crisis.Comment: 7 pages, 7 figure

Efficient Hull Form Design Optimization using Hybrid Evolutionary Algorithm-Morphing Approach

No abstract available

Fungal surface measurements: water contact angles

Non-Peer ReviewedFungal surface properties have been implicated as one of the main factors affecting fungal colonization and adhesion to plant surfaces. Characterization of fungal surfaces through hydrophobic measurements is important for understanding its function. Water contact angles are a direct and simple approach for characterization of fungal surface hydrophobicity. The objective of this study was to evaluate if utilization of undisturbed fungal cultures coupled with versatile image analysis allow for more accurate contact angle measurements. Fungal cultures were grown on agar slide media and contact angles were measured utilizing a modified microscope and digital camera setup, with Low Bond Axisymmetric Drop Shape Analysis Model (LB_ADSA) for contact angle determination. Fungal strains were categorized into hydrophobic, hydrophilic and a newly defined hydroamphiphilic class containing fungi taxa with changing hydrophobicity

Efficient Hull Form Design Optimization using Hybrid Evolutionary Algorithm-Morphing Approach

No abstract available

Self-avoiding walks on scale-free networks

Several kinds of walks on complex networks are currently used to analyze search and navigation in different systems. Many analytical and computational results are known for random walks on such networks. Self-avoiding walks (SAWs) are expected to be more suitable than unrestricted random walks to explore various kinds of real-life networks. Here we study long-range properties of random SAWs on scale-free networks, characterized by a degree distribution $P(k) \sim k^{-\gamma}$. In the limit of large networks (system size $N \to \infty$), the average number $s_n$ of SAWs starting from a generic site increases as $\mu^n$, with $\mu = / - 1$. For finite $N$, $s_n$ is reduced due to the presence of loops in the network, which causes the emergence of attrition of the paths. For kinetic growth walks, the average maximum length, $$, increases as a power of the system size: $\sim N^{\alpha}$, with an exponent $\alpha$ increasing as the parameter $\gamma$ is raised. We discuss the dependence of $\alpha$ on the minimum allowed degree in the network. A similar power-law dependence is found for the mean self-intersection length of non-reversal random walks. Simulation results support our approximate analytical calculations.Comment: 9 pages, 7 figure