10,439 research outputs found
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 as .
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, ,
the queue length distribution decays as and the average delay
time at the hub diverges as in the limit when , 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 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
Efficient Hull Form Design Optimization using Hybrid Evolutionary Algorithm-Morphing Approach
No abstract available
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