3,032 research outputs found

    A Machine-Synesthetic Approach To DDoS Network Attack Detection

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    In the authors' opinion, anomaly detection systems, or ADS, seem to be the most perspective direction in the subject of attack detection, because these systems can detect, among others, the unknown (zero-day) attacks. To detect anomalies, the authors propose to use machine synesthesia. In this case, machine synesthesia is understood as an interface that allows using image classification algorithms in the problem of detecting network anomalies, making it possible to use non-specialized image detection methods that have recently been widely and actively developed. The proposed approach is that the network traffic data is "projected" into the image. It can be seen from the experimental results that the proposed method for detecting anomalies shows high results in the detection of attacks. On a large sample, the value of the complex efficiency indicator reaches 97%.Comment: 12 pages, 2 figures, 5 tables. Accepted to the Intelligent Systems Conference (IntelliSys) 201

    Identifying and characterising price leadership in British supermarkets

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    Price leadership is a concept that lacks precision. We propose a deliberately narrow, falsifiable, definition then develop it, illustrate its feasibility and test it using the two leading British supermarket chains. We find both firms engaging in leading prices upward over a range of products, with the larger being initially more dominant but the smaller increasing leadership activity to take overall leadership over time. However, more price leadership events are price reductions than price increases, consistently led by the smaller firm. Nevertheless, the increases are of larger monetary amounts than the falls, so average basket price increases over time

    Continuity properties of measurable group cohomology

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    A version of group cohomology for locally compact groups and Polish modules has previously been developed using a bar resolution restricted to measurable cochains. That theory was shown to enjoy analogs of most of the standard algebraic properties of group cohomology, but various analytic features of those cohomology groups were only partially understood. This paper re-examines some of those issues. At its heart is a simple dimension-shifting argument which enables one to `regularize' measurable cocycles, leading to some simplifications in the description of the cohomology groups. A range of consequences are then derived from this argument. First, we prove that for target modules that are Fr\'echet spaces, the cohomology groups agree with those defined using continuous cocycles, and hence they vanish in positive degrees when the acting group is compact. Using this, we then show that for Fr\'echet, discrete or toral modules the cohomology groups are continuous under forming inverse limits of compact base groups, and also under forming direct limits of discrete target modules. Lastly, these results together enable us to establish various circumstances under which the measurable-cochains cohomology groups coincide with others defined using sheaves on a semi-simplicial space associated to the underlying group, or sheaves on a classifying space for that group. We also prove in some cases that the natural quotient topologies on the measurable-cochains cohomology groups are Hausdorff.Comment: 52 pages. [Nov 22, 2011:] Major re-write with Calvin C. Moore as new co-author. Results from previous version strengthened and several new results added. [Nov 25, 2012:] Final version now available at springerlink.co

    Assessment of Sharp Injuries among Cameroonian Dental Professionals

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    Objective To assess the prevalence of sharp injury among Cameroonian dental professionals. Materials and Methods A cross-sectional study of 41 dental professionals recruited from 4 out of 10 provinces in Cameroon was conducted in the second half of 2009. A self-administered questionnaire was used to capture information on demography, nature, frequency and causes of sharp injury, post-exposure prophylaxis practice and methods of sharps disposal. Results Thirty-nine dental professionals (95.1%) had experienced sharp injury with 35.9% being once in the preceding 12 months. Needlestick was the most common sharp injury experienced by the respondents. Most of the injuries occurred during recapping of the needle. Activity during which injuries occurred was not significantly associated with type of practice. Twenty three (59.0%) respondents received post-exposure prophylaxis after sustaining sharp injury. Proper disposal of sharps in a special container was observed by 35 (85.4%) of the respondents. Conclusion The prevalence of sharp injuries among Cameroonian dental professionals was high. This justifies an urgent need for concerted effort to reduce sharp injuries in Cameroon dental practices through a comprehensive sharp injury prevention program including work place safety, employee training on guidelines adherence, safe recapping and disposal systems

    Methylomic trajectories across human fetal brain development

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    Open access articleEpigenetic processes play a key role in orchestrating transcriptional regulation during development. The importance of DNA methylation in fetal brain development is highlighted by the dynamic expression of de novo DNA methyltransferases during the perinatal period and neurodevelopmental deficits associated with mutations in the methyl-CpG binding protein 2 (MECP2) gene. However, our knowledge about the temporal changes to the epigenome during fetal brain development has, to date, been limited. We quantified genome-wide patterns of DNA methylation at ∼ 400,000 sites in 179 human fetal brain samples (100 male, 79 female) spanning 23 to 184 d post-conception. We identified highly significant changes in DNA methylation across fetal brain development at >7% of sites, with an enrichment of loci becoming hypomethylated with fetal age. Sites associated with developmental changes in DNA methylation during fetal brain development were significantly underrepresented in promoter regulatory regions but significantly overrepresented in regions flanking CpG islands (shores and shelves) and gene bodies. Highly significant differences in DNA methylation were observed between males and females at a number of autosomal sites, with a small number of regions showing sex-specific DNA methylation trajectories across brain development. Weighted gene comethylation network analysis (WGCNA) revealed discrete modules of comethylated loci associated with fetal age that are significantly enriched for genes involved in neurodevelopmental processes. This is, to our knowledge, the most extensive study of DNA methylation across human fetal brain development to date, confirming the prenatal period as a time of considerable epigenomic plasticity.MRCUniversity of Exeter Medical SchoolWellcome Trus

    Drawing Trees with Perfect Angular Resolution and Polynomial Area

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    We study methods for drawing trees with perfect angular resolution, i.e., with angles at each node v equal to 2{\pi}/d(v). We show: 1. Any unordered tree has a crossing-free straight-line drawing with perfect angular resolution and polynomial area. 2. There are ordered trees that require exponential area for any crossing-free straight-line drawing having perfect angular resolution. 3. Any ordered tree has a crossing-free Lombardi-style drawing (where each edge is represented by a circular arc) with perfect angular resolution and polynomial area. Thus, our results explore what is achievable with straight-line drawings and what more is achievable with Lombardi-style drawings, with respect to drawings of trees with perfect angular resolution.Comment: 30 pages, 17 figure

    Lineage-specific serology confirms Brazilian Atlantic forest lion tamarins, Leontopithecus chrysomelas and Leontopithecus rosalia, as reservoir hosts of Trypanosoma cruzi II (TcII).

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    BACKGROUND: Trypanosoma cruzi, the agent of Chagas disease in humans, has a vast reservoir of mammalian hosts in the Americas, and is classified into six genetic lineages, TcI-TcVI, with a possible seventh, TcBat. Elucidating enzootic cycles of the different lineages is important for understanding the ecology of this parasite, the emergence of new outbreaks of Chagas disease and for guiding control strategies. Direct lineage identification by genotyping is hampered by limitations of parasite isolation and culture. An indirect method is to identify lineage-specific serological reactions in infected individuals; here we describe its application with sylvatic Brazilian primates. METHODS: Synthetic peptides representing lineage-specific epitopes of the T. cruzi surface protein TSSA were used in ELISA with sera from Atlantic Forest Leontopithecus chrysomelas (golden-headed lion tamarin), L. rosalia (golden lion tamarin), Amazonian Sapajus libidinosus (black-striped capuchin) and Alouatta belzebul (red-handed howler monkey). RESULTS: The epitope common to lineages TcII, TcV and TcVI was recognised by sera from 15 of 26 L. chrysomelas and 8 of 13 L. rosalia. For 12 of these serologically identified TcII infections, the identity of the lineage infection was confirmed by genotyping T. cruzi isolates. Of the TcII/TcV/TcVI positive sera 12 of the 15 L. chrysomelas and 2 of the 8 L. rosalia also reacted with the specific epitope restricted to TcV and TcVI. Sera from one of six S. libidinous recognised the TcIV/TcIII epitopes. CONCLUSIONS: This lineage-specific serological surveillance has verified that Atlantic Forest primates are reservoir hosts of at least TcII, and probably TcV and TcVI, commonly associated with severe Chagas disease in the southern cone region of South America. With appropriate reagents, this novel methodology is readily applicable to a wide range of mammal species and reservoir host discovery

    Elevated Paracellular Glucose Flux across Cystic Fibrosis Airway Epithelial Monolayers Is an Important Factor for Pseudomonas aeruginosa Growth.

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    People with cystic fibrosis (CF) who develop related diabetes (CFRD) have accelerated pulmonary decline, increased infection with antibiotic-resistant Pseudomonas aeruginosa and increased pulmonary exacerbations. We have previously shown that glucose concentrations are elevated in airway surface liquid (ASL) of people with CF, particularly in those with CFRD. We therefore explored the hypotheses that glucose homeostasis is altered in CF airway epithelia and that elevation of glucose flux into ASL drives increased bacterial growth, with an effect over and above other cystic fibrosis transmembrane conductance regulator (CFTR)-related ASL abnormalities. The aim of this study was to compare the mechanisms governing airway glucose homeostasis in CF and non-CF primary human bronchial epithelial (HBE) monolayers, under normal conditions and in the presence of Ps. aeruginosa filtrate. HBE-bacterial co-cultures were performed in the presence of 5 mM or 15 mM basolateral glucose to investigate how changes in blood glucose, such as those seen in CFRD, affects luminal Ps. aeruginosa growth. Calu-3 cell monolayers were used to evaluate the potential importance of glucose on Ps. aeruginosa growth, in comparison to other hallmarks of the CF ASL, namely mucus hyperviscosity and impaired CFTR-dependent fluid secretions. We show that elevation of basolateral glucose promotes the apical growth of Ps. aeruginosa on CF airway epithelial monolayers more than non-CF monolayers. Ps. aeruginosa secretions elicited more glucose flux across CF airway epithelial monolayers compared to non-CF monolayers which we propose increases glucose availability in ASL for bacterial growth. In addition, elevating basolateral glucose increased Ps. aeruginosa growth over and above any CFTR-dependent effects and the presence or absence of mucus in Calu-3 airway epithelia-bacteria co-cultures. Together these studies highlight the importance of glucose as an additional factor in promoting Ps. aeruginosa growth and respiratory infection in CF disease

    Optimal Receiver Antenna Location in Indoor Environment Using Dynamic Differential Evolution and Genetic Algorithm

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    [[abstract]]Using the impulse responses of these multipath channels, the bit error rate (BER) performance for binary pulse amplitude modulation impulse radio ultra-wideband communication system is calculated. The optimization location of receiving antenna is investigated by dynamic differential evolution (DDE) and genetic algorithm (GA) to minimize the outage probability. Numerical results show that the performance for reducing BER and outage probability by DDE algorithm is better than that by GA.[[notice]]補正完畢[[incitationindex]]SCI[[booktype]]紙本[[booktype]]電子
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