1,192 research outputs found

    PyFR: An Open Source Framework for Solving Advection-Diffusion Type Problems on Streaming Architectures using the Flux Reconstruction Approach

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    High-order numerical methods for unstructured grids combine the superior accuracy of high-order spectral or finite difference methods with the geometric flexibility of low-order finite volume or finite element schemes. The Flux Reconstruction (FR) approach unifies various high-order schemes for unstructured grids within a single framework. Additionally, the FR approach exhibits a significant degree of element locality, and is thus able to run efficiently on modern streaming architectures, such as Graphical Processing Units (GPUs). The aforementioned properties of FR mean it offers a promising route to performing affordable, and hence industrially relevant, scale-resolving simulations of hitherto intractable unsteady flows within the vicinity of real-world engineering geometries. In this paper we present PyFR, an open-source Python based framework for solving advection-diffusion type problems on streaming architectures using the FR approach. The framework is designed to solve a range of governing systems on mixed unstructured grids containing various element types. It is also designed to target a range of hardware platforms via use of an in-built domain specific language based on the Mako templating engine. The current release of PyFR is able to solve the compressible Euler and Navier-Stokes equations on grids of quadrilateral and triangular elements in two dimensions, and hexahedral elements in three dimensions, targeting clusters of CPUs, and NVIDIA GPUs. Results are presented for various benchmark flow problems, single-node performance is discussed, and scalability of the code is demonstrated on up to 104 NVIDIA M2090 GPUs. The software is freely available under a 3-Clause New Style BSD license (see www.pyfr.org)

    Phylogenetic analysis of A. salmonicida

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    Prevalence of Depression and Anxiety among 10th Standard Exam Going Children in Rural Area of Kancheepuram District

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    Depression is a common illness worldwide, with an estimate of about 350 million as on 2016. Anxiety is a feeling of worry, nervousness, or unease about something with an uncertain outcome. The annual years of healthy life lost per 100,000 people from anxiety disorders in India has increased by 7.2% since 1990, an average of 0.3% a year. The purpose of this study is to know whether the students are depressed and anxious during exam times and if so, in what grade of depression and anxiety the majority of students comes under .And with the results, to make general awareness and pacify the school student regarding their exams. Materials and Methods:  A cross sectional study will be conducted among the school students studying 9th and 10th standard in the field practice areas of the Department of Community Medicine Pondicherry institute of Medical Sciences, Duration of the study is one month (February 2017). Considering the prevalence of Anxiety and Depression as 25%, with 20% absolute precision the sample size calculated was 312. Results: Most of the 9th and 10th standard students are having mild depression, ie 119 students (n) which constitutes about 38.1%. Also on comparing 9th and 10th standard students, 9th standard students are having minimal depression ie 65 students which constitutes about 60.2 %, whereas 10th standard students are having mild depression ie 70 students which constitutes about 51.8%.. Providing counselling for students, the teacher of a class should know the different difficulties of each student of their class and try to solve them in a smooth manner by doing these activities we can reduce the percentage of depression and anxiety among school children’s for an extent

    Prevalence and Determinants of Domestic Accidents in a Rural Area of Kanchipuram District, Tamil Nadu

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    Accident is defined as, ‘‘an unintentional injury which is undesirable, incidental and unplanned event that could have been prevented under circumstances leading to the accident being recognized’’. Accidents are of different types and domestic accidents are a worldwide threat but have seen resurgence in rural India. The main purpose of this study was to determine the prevalence and determinants of domestic accidents in rural area of Tamil Nadu and educate the people to reduce its burden. Materials and method: A community based cross sectional study, using a pre designed and pretested questionnaire was done in a rural area of Kanchipuram district, Tamil Nadu from 4th January 2017 to 31st January 2017. Data was collected from 1560 adults of both sexes and those who were the permanent residents of the study area. History of accident/injury during the past 3 months was obtained to avoid the recall bias. Results: It was found that 11.8 %( n=184) of the total study participants had a history of some form of accident/injury during the past 3 months. Out of these 184 subjects, 56.5 %(n=104) had domestic accidents. It was found that 51 %( n=53) of the domestic accidents have occurred due to ‘Fall’. Maximum numbers of the domestic accidents (42.3%) have occurred while the study subjects were working. Conclusion: Domestic accidents similar to any other disease have their own natural history and a sound knowledge about various determinants is essential to plan and administer prevention and control measures, and thereby reduce their burden especially in rural population. Increased awareness about the determinants will reduce the burden of the domestic accidents as they don’t simply befall on us from fate or bad luck. Keywords: Domestic, Accidents, Injury, Fal

    The Aeromonas salmonicida plasmidome : a model of modular evolution and genetic diversity

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    High-throughput genomic sequencing has helped to reveal the plasmidome of Aeromonas salmonicida. This literature review provides an overview of A. salmonicida's rich plasmidome by presenting all the plasmids identified so far, addressing their biological importance and the functional links between them. The plasmids of A. salmonicida, especially those bearing antibiotic resistance genes, can provide clues about interactions of this species with other pathogens (animals and humans), as is the case for pRAS3-3432 and Chlamydia suis or pSN254b and Salmonella enterica. In addition to antibiotic resistance, plasmids play an important role in the virulence of A. salmonicida, particularly for the subspecies salmonicida and the plasmid pAsa5, which carries genes for the type-three secretion system, a virulence factor essential for the bacterium. The A. salmonicida plasmidome also has many cryptic plasmids with no known biological function, but which can be used for the acquisition of new genetic elements. Striking examples are pAsa7 and pAsaXII that provide, respectively, resistance to chloramphenicol and formaldehyde and are derivatives of cryptic pAsa2

    Genomic and phenotypic characterization of an atypical Aeromonas salmonicida strain isolated from a lumpfish and producing unusual granular structures

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    Aeromonas salmonicida strains are roughly classified into two categories, typical and atypical strains. The latter mainly regroup isolates that present unusual phenotypes or hosts, comparatively to the typical strains that belong to the salmonicida subspecies. This study focuses on an uncharacterized atypical strain, M18076-11, isolated from lumpfish (Cyclopterus lumpus) and not part of the four recognized Aeromonas salmonicida subspecies. This isolate presents an unreported phenotype in the A. salmonicida species: the formation of large granular aggregates. Granules are formed of a heterogeneous mix of live and dead cells, with live cells composing the majority of the population. Even if no mechanism was determined to cause cellular aggregation, small globular structures at the cell surface were observed, which might affect granular formation. Pan-genome phylogenetic analysis indicated that this strain groups alongside the masoucida subspecies. However, phenotypic tests showed that these strains have diverging phenotypes, suggesting that M18076-11 might belong to a new subspecies. Also, a pAsal1-like plasmid, which was only reported in strains of the subspecies salmonicida, was discovered in M18076-11. This study sheds light on unsuspected diversity in A. salmonicida subspecies and stresses the need of thorough identification when a new strain is encountered, as unique traits might be discovered

    GĂ©nomique d'Aeromonas salmonicida et de ses phages

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    Depuis la dĂ©couverte de la pĂ©nicilline par Sir Alexander Fleming, les antibiotiques ont jouĂ© un rĂŽle primordial et incontestable en mĂ©decine moderne en aidant Ă  combattre les infections bactĂ©riennes. Cependant, les bactĂ©ries ont la capacitĂ© de se protĂ©ger par diffĂ©rents moyens des molĂ©cules antibiotiques. La surutilisation de ces molĂ©cules a accĂ©lĂ©rĂ© le phĂ©nomĂšne de rĂ©sistance aux antibiotiques, rendant difficile, voire impossible, le traitement de certaines maladies infectieuses par cette approche. La rĂ©sistance aux antibiotiques est une problĂ©matique d’envergure mondiale qui touche aussi nĂ©gativement l’aquaculture, oĂč les infections bactĂ©riennes peuvent causer d’importantes pertes Ă©conomiques. L’une de ces bactĂ©ries est Aeromonas salmonicida subsp. salmonicida, l’agent Ă©tiologique de la furonculose. Bien qu’il fĂ»t dĂ©jĂ  connu que plusieurs souches de cette bactĂ©rie Ă©taient porteuses de plasmides confĂ©rant des rĂ©sistances aux antibiotiques, l’ampleur de la problĂ©matique Ă©tait encore inconnue. Les bactĂ©riophages (phages) sont des virus infectant spĂ©cifiquement les bactĂ©ries. Cette capacitĂ© Ă  lyser les bactĂ©ries leur a valu d’ĂȘtre utilisĂ©s dans un contexte thĂ©rapeutique presque dĂšs leur dĂ©couverte au dĂ©but du 20e siĂšcle. Cependant, l’avĂšnement des antibiotiques a fait en sorte que la thĂ©rapie par les phages a Ă©tĂ© oubliĂ©e dans plusieurs pays occidentaux. Maintenant que la rĂ©sistance aux antibiotiques est devenue une inquiĂ©tude pour la pĂ©rennitĂ© de notre sociĂ©tĂ©, plusieurs Ă©tudes suggĂšrent que la thĂ©rapie par les phages pourrait ĂȘtre une alternative ou un complĂ©ment aux traitements par antibiotiques. La prĂ©sente thĂšse avait comme objectifs : (1) d’explorer la diversitĂ© gĂ©nomique causant une rĂ©sistance aux antibiotiques chez A. salmonicida subsp. salmonicida et (2) d’investiguer le potentiel d’un traitement par les phages pour contrer les infections causĂ©es par cette bactĂ©rie. Il a Ă©tĂ© possible de mettre Ă  jour et de caractĂ©riser cinq nouveaux plasmides avec des gĂšnes de rĂ©sistance aux antibiotiques chez A. salmonicida subsp. salmonicida. De plus, la prĂ©sence de deux de ces plasmides (pAB5S9b et pSN254b) causent une rĂ©sistance Ă  tous les antibiotiques approuvĂ©s par le gouvernement canadien pour une utilisation par l’industrie piscicole. Avant d’investiguer la diversitĂ© des phages infectant A. salmonicida subsp. salmonicida, il Ă©tait crucial de mieux connaĂźtre la bactĂ©rie d’intĂ©rĂȘt. Plusieurs phages sont connus pour avoir un spectre lytique Ă©troit, n’infectant ainsi que certaines souches ou certaines sousespĂšces d’une bactĂ©rie. Or, la structure intra-espĂšce d’A. salmonicida Ă©tait encore mal dĂ©finie. De plus, l’une des sous-espĂšces d’A. salmonicida, pectinolytica, est considĂ©rĂ©e comme mĂ©sophile avec la capacitĂ© de croĂźtre Ă  37°C, alors que les autres sous-espĂšces, comme salmonicida, sont limitĂ©es Ă  des tempĂ©ratures d’environ 20°C et sont par consĂ©quent qualifiĂ©es de psychrophiles. En caractĂ©risant de nouvelles souches mĂ©sophiles, mes travaux ont mis en lumiĂšre que les sĂ©quences d’insertion peuvent ĂȘtre une raison pour expliquer cette dichotomie. De plus, il a Ă©tĂ© possible de dĂ©montrer une grande diversitĂ© gĂ©nĂ©tique chez les souches mĂ©sophiles, comparativement Ă  celles psychrophiles. Afin de vĂ©rifier le potentiel d’un traitement par les phages contre la furonculose, trois phages spĂ©cifiques Ă  A. salmonicida subsp. salmonicida ont Ă©tĂ© isolĂ©s de l’environnement. L'ADN de ces phages, en plus de celui de neuf autres disponibles Ă  la collection FĂ©lix d’HĂ©relle, a Ă©tĂ© sĂ©quencĂ© Ă  haut-dĂ©bit sur un appareil MiSeq d’Illumina. En comparant ces sĂ©quences gĂ©nomiques Ă  celles dĂ©jĂ  disponibles publiquement, il a Ă©tĂ© possible de dĂ©terminer six groupes gĂ©nomiques de phages contre A. salmonicida subsp. salmonicida. Les 12 phages disponibles pour la prĂ©sente Ă©tude ont Ă©tĂ© testĂ©s sur 65 souches d’A. salmonicida (incluant des sous-espĂšces autres que salmonicida), permettant de dresser un portrait de la capacitĂ© lytique de chacun de ces virus. Cette analyse a mis en lumiĂšre trois groupes de phages ayant des capacitĂ©s lytiques variables. De plus, il a Ă©tĂ© possible de montrer que d’autres sous-espĂšces d’A. salmonicida psychrophiles peuvent ĂȘtre infectĂ©es par les phages isolĂ©s Ă  partir de la sous-espĂšce salmonicida. Cependant, les souches mĂ©sophiles d’A. salmonicida sont insensibles Ă  ces phages. Cette Ă©tude doctorale a montrĂ© que la rĂ©sistance aux antibiotiques est un problĂšme d’envergure dont l’ampleur Ă©tait insoupçonnĂ©e chez A. salmonicida subsp. salmonicida. Elle a aussi permis d’investiguer le potentiel de la thĂ©rapie par les phages.Since the discovery of penicillin by Sir Alexander Fleming, antibiotics have played a paramount and indisputable role in modern medicine in helping to treat bacterial infections. However, bacteria have the ability to protect themselves against antibiotics by various mechanisms. The overuse of these molecules has accelerated the phenomenon of antibiotic resistance, making it difficult, if not impossible, to treat certain bacterial infections. Antibiotic resistance is a global problem that also negatively affects aquaculture, where bacterial infections can cause significant economic losses. One of these bacteria is Aeromonas salmonicida subsp. salmonicida, the etiologic agent of furunculosis. Although it was already known that several strains of this bacterium were carriers of plasmids conferring resistance to antibiotics, the extent of the problem was still unknown before this study. Bacteriophages (phages) are viruses specifically infecting bacteria. Their ability to lyse bacteria has been used in a therapeutic context almost as soon as they were discovered at the beginning of the 20th century. However, the advent of antibiotics has meant that phage therapy was forgotten in several Western countries. Now that antibiotic resistance has become a significant concern for the sustainability of our society, several studies suggest that phage therapy could be an alternative or supplement to antibiotic treatments. The objectives of this thesis were: (1) to explore the genomic diversity causing resistance to antibiotics in A. salmonicida subsp. salmonicida and (2) to investigate the potential of phage therapy to treat infections caused by this bacterium. Five new plasmids conferring antibiotic resistance to A. salmonicida subsp. salmonicida were discovered and characterized. Two of these plasmids, pAB5S9b and pSN254b, cause resistance to all antibiotics approved by the Canadian government for use in the fish industry. Before investigating the diversity of phages infecting A. salmonicida subsp. salmonicida, it was crucial to better know the bacterium of interest. Several phages are known to have a narrow host spectrum, infecting certain strains or subspecies. Until the present doctoral study, the intra-species structure of A. salmonicida was poorly defined. In addition, one of the subspecies of A. salmonicida, pectinolytica, is considered mesophilic with the ability to grow at 37°C, while other subspecies, such as salmonicida, are limited to growth temperatures around 20°C and are therefore considered psychrophilic. By characterizing new mesophilic strains, we found that insertion sequences may be a reason for this dichotomy. In addition, it was possible to demonstrate a high genetic diversity in mesophilic strains compared to psychrophilic strains. In order to verify the potential of phage treatment against furunculosis, three phages specific to A. salmonicida subsp. salmonicida were isolated from the environment. The genomic DNA of these phages, in addition to that of nine other phages available at the Felix d'HĂ©relle collection, was sequenced on an Illumina MiSeq device. By comparing these genomic sequences to those already available publicly, it was possible to determine six genomic groups of phages infecting A. salmonicida subsp. salmonicida. The 12 phages available were tested on 65 strains of A. salmonicida (including subspecies other than salmonicida), providing the host range of each virus. This analysis revealed three groups of phages with variable lytic capacities. In addition, it was possible to show that other psychrophilic subspecies of A. salmonicida can be infected by phages isolated from the subspecies salmonicida. However, the mesophilic strains of A. salmonicida are insensitive to these phages. This doctoral study showed that resistance to antibiotics is a large-scale problem in A. salmonicida subsp. salmonicida, and that phage therapy may represent one of the solutions to the growing concer

    Étude du gĂ©nome chloroplastique des algues vertes de la classe Chlorophyceae

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    Les algues unicellulaires de la classe Chlorophyceae sont particuliÚrement étudiées pour leur potentiel économique dans la production de biocarburant. La premiÚre taxonomie de cette classe a été faite avec l'avÚnement de la microscopie électronique et par la suite avec des phylogénies moléculaires. Cette lignée se divise en deux groupes : OCC (Oedogoniales + Chaetophorales + Chaetopeltidales) et CS (Chlamydomonadales + Sphaeropleales). Il existe de profondes incertitudes sur les positions phylogénétiques des organismes à la base du groupe CS. Afin de renforcer la phylogénie de ces organismes, les génomes chloroplastiques de cinq algues basales ont été séquencés à l'aide de la technologie de nouvelle génération 454 et assemblés de novo. Une analyse phylogénétique de 69 séquences de protéines a permis de montrer que trois des cinq organismes classés dans l'ordre Chlamydomonadales par la littérature actuelle sont en fait basaux dans l'ordre Sphaeropleales. Ce reclassement phylogénétique implique de nouvelles hypothÚses sur l'évolution des corps flagellaires.The unicellular algae class Chlorophyceae is notably studied for its economic potential for biofuel production. The first taxonomy of this class was made with the advent of electron microscopy and subsequently with molecular phylogenies. This lineage is divided into two groups: OCC (Oedogoniales + Chaetophorales + Chaetopeltidales) and CS (Chlamydomonadales + Sphaeropleales). There are deep uncertainties about the phylogenetic positions of the organisms at the base of the CS group. To strengthen the phylogeny of these organisms, the chloroplast genomes sequences of five basal algae were obtained by Roche 454 pyrosequencing . A phylogenetic analysis of sixty-nine chloroplast protein sequences revealed that three of these five organisms, listed in the order Chlamydomonadales by the current literature, are in fact basal in the order Sphaeropleales. This phylogenetic reclassification involves a new hypothesis on the evolution of flagellar bodies

    Beyond the A-layer : adsorption of lipopolysaccharides and characterization of bacteriophage-insensitive mutants of Aeromonas salmonicida subsp. salmonicida

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    Aeromonas salmonicida subsp. salmonicida is a fish pathogen that causes furunculosis. Antibiotherapy used to treat furunculosis in fish has led to resistance. Virulent phages are increasingly seen as alternatives or complementary treatments against furunculosis in aquaculture environments. For phage therapy to be successful, it is essential to study the natural mechanisms of phage resistance in A. salmonicida subsp. salmonicida. Here, we generated bacteriophage‐insensitive mutants (BIMs) of A. salmonicida subsp. salmonicida, using a myophage with broad host range and characterized them. Phage plaques were different depending on whether the A‐layer surface array protein was expressed or not. The genome analysis of the BIMs helped to identify mutations in genes involved in the biogenesis of lipopolysaccharides (LPS) and on an uncharacterized gene (ASA_1998). The characterization of the LPS profile and gene complementation assays identified LPS as a phage receptor and confirmed the involvement of the uncharacterized protein ASA_1998 in phage infection. In addition, we confirmed that the presence of an A‐layer at the bacterial surface could act as protection against phages. This study brings new elements into our understanding of the phage adsorption to A. salmonicida subsp. salmonicida cells

    An Empirical Study on Different Ranking Methods for Effective Data Classification

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    Ranking is the attribute selection technique used in the pre-processing phase to emphasize the most relevant attributes which allow models of classification simpler and easy to understand. It is a very important and a central task for information retrieval, such as web search engines, recommendation systems, and advertisement systems. A comparison between eight ranking methods was conducted. Ten different learning algorithms (NaiveBayes, J48, SMO, JRIP, Decision table, RandomForest, Multilayerperceptron, Kstar) were used to test the accuracy. The ranking methods with different supervised learning algorithms give different results for balanced accuracy. It was shown the selection of ranking methods could be important for classification accuracy
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