683 research outputs found

    On quantum equivalence of dual sigma models: SL(3)SL(3) examples

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    The equivalence of several SL(3)SL(3) sigma models and their special Abelian duals is investigated in the two loop order of perturbation theory. The investigation is based on extracting and comparing various β\beta functions of the original and dual models. The role of the discrete global symmetries is emphasized.Comment: Plain TEX, 24 page

    Optimal infinite scheduling for multi-priced timed automata

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    This paper is concerned with the derivation of infinite schedules for timed automata that are in some sense optimal. To cover a wide class of optimality criteria we start out by introducing an extension of the (priced) timed automata model that includes both costs and rewards as separate modelling features. A precise definition is then given of what constitutes optimal infinite behaviours for this class of models. We subsequently show that the derivation of optimal non-terminating schedules for such double-priced timed automata is computable. This is done by a reduction of the problem to the determination of optimal mean-cycles in finite graphs with weighted edges. This reduction is obtained by introducing the so-called corner-point abstraction, a powerful abstraction technique of which we show that it preserves optimal schedules

    Non-Strict Independence-Based Program Parallelization Using Sharing and Freeness Information.

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    The current ubiquity of multi-core processors has brought renewed interest in program parallelization. Logic programs allow studying the parallelization of programs with complex, dynamic data structures with (declarative) pointers in a comparatively simple semantic setting. In this context, automatic parallelizers which exploit and-parallelism rely on notions of independence in order to ensure certain efficiency properties. “Non-strict” independence is a more relaxed notion than the traditional notion of “strict” independence which still ensures the relevant efficiency properties and can allow considerable more parallelism. Non-strict independence cannot be determined solely at run-time (“a priori”) and thus global analysis is a requirement. However, extracting non-strict independence information from available analyses and domains is non-trivial. This paper provides on one hand an extended presentation of our classic techniques for compile-time detection of non-strict independence based on extracting information from (abstract interpretation-based) analyses using the now well understood and popular Sharing + Freeness domain. This includes algorithms for combined compile-time/run-time detection which involve special run-time checks for this type of parallelism. In addition, we propose herein novel annotation (parallelization) algorithms, URLP and CRLP, which are specially suited to non-strict independence. We also propose new ways of using the Sharing + Freeness information to optimize how the run-time environments of goals are kept apart during parallel execution. Finally, we also describe the implementation of these techniques in our parallelizing compiler and recall some early performance results. We provide as well an extended description of our pictorial representation of sharing and freeness information

    IL-22 mediates goblet cell hyperplasia and worm expulsion in intestinal helminth infection.

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    Type 2 immune responses are essential in protection against intestinal helminth infections. In this study we show that IL-22, a cytokine important in defence against bacterial infections in the intestinal tract, is also a critical mediator of anti-helminth immunity. After infection with Nippostrongylus brasiliensis, a rodent hookworm, IL-22-deficient mice showed impaired worm expulsion despite normal levels of type 2 cytokine production. The impaired worm expulsion correlated with reduced goblet cell hyperplasia and reduced expression of goblet cell markers. We further confirmed our findings in a second nematode model, the murine whipworm Trichuris muris. T.muris infected IL-22-deficient mice had a similar phenotype to that seen in N.brasiliensis infection, with impaired worm expulsion and reduced goblet cell hyperplasia. Ex vivo and in vitro analysis demonstrated that IL-22 is able to directly induce the expression of several goblet cell markers, including mucins. Taken together, our findings reveal that IL-22 plays an important role in goblet cell activation, and thus, a key role in anti-helminth immunity

    C^2/Z_n Fractional branes and Monodromy

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    We construct geometric representatives for the C^2/Z_n fractional branes in terms of branes wrapping certain exceptional cycles of the resolution. In the process we use large radius and conifold-type monodromies, and also check some of the orbifold quantum symmetries. We find the explicit Seiberg-duality which connects our fractional branes to the ones given by the McKay correspondence. We also comment on the Harvey-Moore BPS algebras.Comment: 34 pages, v1 identical to v2, v3: typos fixed, discussion of Harvey-Moore BPS algebras update

    The Test Your Memory cognitive screening tool: sociodemographic and cardiometabolic risk correlates in a population-based study of older British men.

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    OBJECTIVE: This study aimed to examine the association of Test Your Memory (TYM)-defined cognitive impairment groups with known sociodemographic and cardiometabolic correlates of cognitive impairment in a population-based study of older adults. METHODS: Participants were members of the British Regional Heart Study, a cohort across 24 British towns initiated in 1978-1980. Data stemmed from 1570 British men examined in 2010-2012, aged 71-92 years. Sociodemographic and cardiometabolic factors were compared between participants defined as having TYM scores in the normal cognitive ageing, mild cognitive impairment (MCI) and severe cognitive impairment (SCI) groups, defined as ≥46 (45 if ≥80 years of age), ≥33 and <33, respectively. RESULTS: Among 1570 men, 636 (41%) were classified in the MCI and 133 (8%) in the SCI groups. Compared with participants in the normal cognitive ageing category, individuals with SCI were characterized primarily by lower socio-economic position (odds ratio (OR) = 6.15, 95% confidence interval (CI) 4.00-9.46), slower average walking speed (OR = 3.36, 95% CI 2.21-5.10), mobility problems (OR = 4.61, 95% CI 3.04-6.97), poorer self-reported overall health (OR = 2.63, 95% CI 1.79-3.87), obesity (OR = 2.59, 95% CI 1.72-3.91) and impaired lung function (OR = 2.25, 95% CI 1.47-3.45). A similar albeit slightly weaker pattern was observed for participants with MCI. CONCLUSION: Sociodemographic and lifestyle factors as well as adiposity measures, lung function and poor overall health are associated with cognitive impairments in late life. The correlates of cognitive abilities in the MCI and SCI groups, as defined by the TYM, resemble the risk profile for MCI and Alzheimer's disease outlined in current epidemiological models. © 2016 The Authors. International Journal of Geriatric Psychiatry Published by John Wiley & Sons, Ltd

    A genetic algorithm-Bayesian network approach for the analysis of metabolomics and spectroscopic data: application to the rapid detection of Bacillus spores and identification of Bacillus species

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    Background The rapid identification of Bacillus spores and bacterial identification are paramount because of their implications in food poisoning, pathogenesis and their use as potential biowarfare agents. Many automated analytical techniques such as Curie-point pyrolysis mass spectrometry (Py-MS) have been used to identify bacterial spores giving use to large amounts of analytical data. This high number of features makes interpretation of the data extremely difficult We analysed Py-MS data from 36 different strains of aerobic endospore-forming bacteria encompassing seven different species. These bacteria were grown axenically on nutrient agar and vegetative biomass and spores were analyzed by Curie-point Py-MS. Results We develop a novel genetic algorithm-Bayesian network algorithm that accurately identifies sand selects a small subset of key relevant mass spectra (biomarkers) to be further analysed. Once identified, this subset of relevant biomarkers was then used to identify Bacillus spores successfully and to identify Bacillus species via a Bayesian network model specifically built for this reduced set of features. Conclusions This final compact Bayesian network classification model is parsimonious, computationally fast to run and its graphical visualization allows easy interpretation of the probabilistic relationships among selected biomarkers. In addition, we compare the features selected by the genetic algorithm-Bayesian network approach with the features selected by partial least squares-discriminant analysis (PLS-DA). The classification accuracy results show that the set of features selected by the GA-BN is far superior to PLS-DA

    Dapsone induced cholangitis as a part of dapsone syndrome: a case report

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    BACKGROUND: Dapsone can rarely cause a hypersensitivity reaction called dapsone syndrome, consisting of fever, hepatitis, exfoliative dermatitis, lymphadenopathy and hemolytic anemia. Dapsone syndrome is a manifestation of the DRESS (drug rash with eosinophilia and systemic symptoms) syndrome which is a serious condition that has been reported in association with various drugs. Cholangitis in dapsone syndrome has not been reported so far in the world literature. CASE PRESENTATION: We report a patient who presented with fever, exfoliative dermatitis, jaundice and anemia within three weeks of starting of dapsone therapy. These features are typical of dapsone syndrome, which is due to dapsone hypersensitivity and is potentially fatal. Unlike previous reports of hepatitic or cholestatic injury in dapsone syndrome we report here a case that had cholangitic liver injury. It responded to corticosteroids. CONCLUSION: We conclude that cholangitis, though unusual, can also form a part of dapsone syndrome. Physicians should be aware of this unusual picture of potentially fatal dapsone syndrome

    Structural correlations in bacterial metabolic networks

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    <p>Abstract</p> <p>Background</p> <p>Evolution of metabolism occurs through the acquisition and loss of genes whose products acts as enzymes in metabolic reactions, and from a presumably simple primordial metabolism the organisms living today have evolved complex and highly variable metabolisms. We have studied this phenomenon by comparing the metabolic networks of 134 bacterial species with known phylogenetic relationships, and by studying a neutral model of metabolic network evolution.</p> <p>Results</p> <p>We consider the 'union-network' of 134 bacterial metabolisms, and also the union of two smaller subsets of closely related species. Each reaction-node is tagged with the number of organisms it belongs to, which we denote organism degree (OD), a key concept in our study. Network analysis shows that common reactions are found at the centre of the network and that the average OD decreases as we move to the periphery. Nodes of the same OD are also more likely to be connected to each other compared to a random OD relabelling based on their occurrence in the real data. This trend persists up to a distance of around five reactions. A simple growth model of metabolic networks is used to investigate the biochemical constraints put on metabolic-network evolution. Despite this seemingly drastic simplification, a 'union-network' of a collection of unrelated model networks, free of any selective pressure, still exhibit similar structural features as their bacterial counterpart.</p> <p>Conclusions</p> <p>The OD distribution quantifies topological properties of the evolutionary history of bacterial metabolic networks, and lends additional support to the importance of horizontal gene transfer during bacterial metabolic evolution where new reactions are attached at the periphery of the network. The neutral model of metabolic network growth can reproduce the main features of real networks, but we observe that the real networks contain a smaller common core, while they are more similar at the periphery of the network. This suggests that natural selection and biochemical correlations can act both to diversify and to narrow down metabolic evolution.</p

    A large scale hearing loss screen reveals an extensive unexplored genetic landscape for auditory dysfunction

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    The developmental and physiological complexity of the auditory system is likely reflected in the underlying set of genes involved in auditory function. In humans, over 150 non-syndromic loci have been identified, and there are more than 400 human genetic syndromes with a hearing loss component. Over 100 non-syndromic hearing loss genes have been identified in mouse and human, but we remain ignorant of the full extent of the genetic landscape involved in auditory dysfunction. As part of the International Mouse Phenotyping Consortium, we undertook a hearing loss screen in a cohort of 3006 mouse knockout strains. In total, we identify 67 candidate hearing loss genes. We detect known hearing loss genes, but the vast majority, 52, of the candidate genes were novel. Our analysis reveals a large and unexplored genetic landscape involved with auditory function
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