278 research outputs found

    Hilbert-Post completeness for the state and the exception effects

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    In this paper, we present a novel framework for studying the syntactic completeness of computational effects and we apply it to the exception effect. When applied to the states effect, our framework can be seen as a generalization of Pretnar's work on this subject. We first introduce a relative notion of Hilbert-Post completeness, well-suited to the composition of effects. Then we prove that the exception effect is relatively Hilbert-Post complete, as well as the "core" language which may be used for implementing it; these proofs have been formalized and checked with the proof assistant Coq.Comment: Siegfried Rump (Hamburg University of Technology), Chee Yap (Courant Institute, NYU). Sixth International Conference on Mathematical Aspects of Computer and Information Sciences , Nov 2015, Berlin, Germany. 2015, LNC

    An Infrared Coronagraphic Survey for Substellar Companions

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    We have used the F160W filter (1.4-1.8 um) and the coronagraph on the Near-InfraRed Camera and Multi-Object Spectrometer (NICMOS) on the Hubble Space Telescope (HST) to survey 45 single stars with a median age of 0.15 Gyr, an average distance of 30 pc, and an average H-magnitude of 7 mag. For the median age we were capable of detecting a 30 M_Jup companion at separations between 15 and 200 AU. A 5 M_Jup object could have been detected at 30 AU around 36% of our primaries. For several of our targets that were less than 30 Myr old, the lower mass limit was as low as a Jupiter mass, well into the high mass planet region. Results of the entire survey include the proper motion verification of five low-mass stellar companions, two brown dwarfs (HR7329B and TWA5B) and one possible brown dwarf binary (Gl 577B/C).Comment: 11 figures, accepted by A

    Research-Based Web Design & Usability Guidelines [2006 edition]

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    The new edition of the U.S. Department of Health and Human Services’ (HHS) Research-Based Web Design and Usability Guidelines. These guidelines reflect HHS’ commitment to identifying innovative, research-based approaches that result in highly responsive and easy-to-use Web sites for the public. These guidelines help move us in that direction by providing practical, yet authoritative, guidance on a broad range of Web design and communication issues. Having access to the best available research helps to ensure we make the right decisions the first time around and reduces the possibility of errors and costly mistakes

    Synchronization in periodically driven and coupled stochastic systems-A discrete state approach

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    Wir untersuchen das Verhalten von stochastischen bistabilen und erregbaren Systemen auf der Basis einer Modellierung mit diskreten ZustĂ€nden. In ErgĂ€nzung zum bekannten Markovschen Zwei-Zustandsmodell bistabiler stochastischer Dynamik stellen wir ein nicht Markovsches Drei-Zustandsmodell fĂŒr erregbare Systeme vor. Seine relative Einfachheit, verglichen mit stochastischen Modellen erregbarer Dynamik mit kontinuierlichem Phasenraum, ermöglicht eine teilweise analytische Auswertung in verschiedenen ZusammenhĂ€ngen. ZunĂ€chst untersuchen wir den gemeinsamen Einfluß eines periodischen Treibens und Rauschens. Dieser wird entweder mit Hilfe spektraler GrĂ¶ĂŸen oder durch Synchronisation des Systems mit dem treibenden Signal charakterisiert. Wir leiten analytische AusdrĂŒcke fĂŒr die spektrale LeistungsverstĂ€rkung und das Signal-zu-Rauschen VerhĂ€ltnis fĂŒr periodisch getriebene Renewal-Prozesse her und wenden diese auf das diskrete Modell fĂŒr erregbare Dynamik an. Stochastische Synchronization des Systems mit dem treibenden Signal wird auf der Basis der Diffusionseigenschaften der Übergangsereignisse zwischen den diskreten ZustĂ€nden untersucht. Wir leiten allgemeine Formeln her, um die mittlere HĂ€ufigkeit dieser Ereignisse sowie deren effektiven Diffusionskoeffizienten zu berechnen. Über die konkrete Anwendung auf die untersuchten diskreten Modelle hinaus stellen diese Ergebnisse ein neues Werkzeug fĂŒr die Untersuchung periodischer Renewal-Prozesse dar. Schließlich betrachten wir noch das Verhalten global gekoppelter bistabiler und erregbarer Systeme. Im Gegensatz zu bistabilen System können erregbare Systeme synchronisiert werden und zeigen kohĂ€rente Oszillationen. Alle Untersuchungen des nicht Markovschen Drei-Zustandsmodells werden mit dem prototypischen Modell fĂŒr erregbare Dynamik, dem FitzHugh-Nagumo System, verglichen und zeigen eine gute Übereinstimmung.We investigate the behavior of stochastic bistable and excitable dynamics based on a discrete state modeling. In addition to the well known Markovian two state model for bistable dynamics we introduce a non Markovian three state model for excitable systems. Its relative simplicity compared to stochastic models of excitable dynamics with continuous phase space allows to obtain analytical results in different contexts. First, we study the joint influence of periodic signals and noise, both based on a characterization in terms of spectral quantities and in terms of synchronization with the periodic driving. We present expressions for the spectral power amplification and signal to noise ratio for renewal processes driven by periodic signals and apply these results to the discrete model for excitable systems. Stochastic synchronization of the system to the driving signal is investigated based on diffusion properties of the transition events between the discrete states. We derive general results for the mean frequency and effective diffusion coefficient which, beyond the application to the discrete models considered in this work, provide a new tool in the study of periodically driven renewal processes. Finally the behavior of globally coupled excitable and bistable units is investigated based on the discrete state description. In contrast to the bistable systems, the excitable system exhibits synchronization and thus coherent oscillations. All investigations of the non Markovian three state model are compared with the prototypical continuous model for excitable dynamics, the FitzHugh-Nagumo system, revealing a good agreement between both models

    Impairment of gut microbial biotin metabolism and host biotin status in severe obesity: effect of biotin and prebiotic supplementation on improved metabolism

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    Objectives Gut microbiota is a key component in obesity and type 2 diabetes, yet mechanisms and metabolites central to this interaction remain unclear. We examined the human gut microbiome\u27s functional composition in healthy metabolic state and the most severe states of obesity and type 2 diabetes within the MetaCardis cohort. We focused on the role of B vitamins and B7/B8 biotin for regulation of host metabolic state, as these vitamins influence both microbial function and host metabolism and inflammation. Design We performed metagenomic analyses in 1545 subjects from the MetaCardis cohorts and different murine experiments, including germ-free and antibiotic treated animals, faecal microbiota transfer, bariatric surgery and supplementation with biotin and prebiotics in mice. Results Severe obesity is associated with an absolute deficiency in bacterial biotin producers and transporters, whose abundances correlate with host metabolic and inflammatory phenotypes. We found suboptimal circulating biotin levels in severe obesity and altered expression of biotin-associated genes in human adipose tissue. In mice, the absence or depletion of gut microbiota by antibiotics confirmed the microbial contribution to host biotin levels. Bariatric surgery, which improves metabolism and inflammation, associates with increased bacterial biotin producers and improved host systemic biotin in humans and mice. Finally, supplementing high-fat diet-fed mice with fructo-oligosaccharides and biotin improves not only the microbiome diversity, but also the potential of bacterial production of biotin and B vitamins, while limiting weight gain and glycaemic deterioration. Conclusion Strategies combining biotin and prebiotic supplementation could help prevent the deterioration of metabolic states in severe obesity

    Transcriptome of Aphanomyces euteiches: New Oomycete Putative Pathogenicity Factors and Metabolic Pathways

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    Aphanomyces euteiches is an oomycete pathogen that causes seedling blight and root rot of legumes, such as alfalfa and pea. The genus Aphanomyces is phylogenically distinct from well-studied oomycetes such as Phytophthora sp., and contains species pathogenic on plants and aquatic animals. To provide the first foray into gene diversity of A. euteiches, two cDNA libraries were constructed using mRNA extracted from mycelium grown in an artificial liquid medium or in contact to plant roots. A unigene set of 7,977 sequences was obtained from 18,864 high-quality expressed sequenced tags (ESTs) and characterized for potential functions. Comparisons with oomycete proteomes revealed major differences between the gene content of A. euteiches and those of Phytophthora species, leading to the identification of biosynthetic pathways absent in Phytophthora, of new putative pathogenicity genes and of expansion of gene families encoding extracellular proteins, notably different classes of proteases. Among the genes specific of A. euteiches are members of a new family of extracellular proteins putatively involved in adhesion, containing up to four protein domains similar to fungal cellulose binding domains. Comparison of A. euteiches sequences with proteomes of fully sequenced eukaryotic pathogens, including fungi, apicomplexa and trypanosomatids, allowed the identification of A. euteiches genes with close orthologs in these microorganisms but absent in other oomycetes sequenced so far, notably transporters and non-ribosomal peptide synthetases, and suggests the presence of a defense mechanism against oxidative stress which was initially characterized in the pathogenic trypanosomatids

    Analyse écorégionale marine de Nouvelle-Calédonie : atelier d'identification des aires de conservation prioritaires

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    Dans le cadre de l'initiative pour les rĂ©cifs coralliens du Pacifique sud (CRISP), le WWF-France a souhaitĂ© dĂ©velopper un projet pour la protection des rĂ©cifs et des lagons nĂ©o-calĂ©doniens. L'atelier, qui s'est dĂ©roulĂ© les 10 et 11 aoĂ»t Ă  NoumĂ©a, avait pour objectif de rassembler les scientifiques et les experts du lagon nĂ©ocalĂ©donien pour identifier, sur la base de leur connaissance experte, les zones les plus remarquables du lagon (richesse, endĂ©misme, originalitĂ© des faunes et flores, espĂšces emblĂ©matiques, zones d'intĂ©rĂȘt fonctionnel) sur lesquelles doivent porter en prioritĂ© les efforts de conservation. Il a permis d'identifier 20 aires prioritaires pour la conservation, parmi lesquelles 6 ont un intĂ©rĂȘt mondial, 4 ont un intĂ©rĂȘt sur le plan rĂ©gional, les autres ayant un intĂ©rĂȘt local

    De novo TBR1 variants cause a neurocognitive phenotype with ID and autistic traits:report of 25 new individuals and review of the literature

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    TBR1, a T-box transcription factor expressed in the cerebral cortex, regulates the expression of several candidate genes for autism spectrum disorders (ASD). Although TBR1 has been reported as a high-confidence risk gene for ASD and intellectual disability (ID) in functional and clinical reports since 2011, TBR1 has only recently been recorded as a human disease gene in the OMIM database. Currently, the neurodevelopmental disorders and structural brain anomalies associated with TBR1 variants are not well characterized. Through international data sharing, we collected data from 25 unreported individuals and compared them with data from the literature. We evaluated structural brain anomalies in seven individuals by analysis of MRI images, and compared these with anomalies observed in TBR1 mutant mice. The phenotype included ID in all individuals, associated to autistic traits in 76% of them. No recognizable facial phenotype could be identified. MRI analysis revealed a reduction of the anterior commissure and suggested new features including dysplastic hippocampus and subtle neocortical dysgenesis. This report supports the role of TBR1 in ID associated with autistic traits and suggests new structural brain malformations in humans. We hope this work will help geneticists to interpret TBR1 variants and diagnose ASD probands
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