4,129 research outputs found

    Stochastic inviscid shell models: well-posedness and anomalous dissipation

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    In this paper we study a stochastic version of an inviscid shell model of turbulence with multiplicative noise. The deterministic counterpart of this model is quite general and includes inviscid GOY and Sabra shell models of turbulence. We prove global weak existence and uniqueness of solutions for any finite energy initial condition. Moreover energy dissipation of the system is proved in spite of its formal energy conservation.Comment: v2 has updated introductio

    Linear Stochastic Dyadic Model

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    We discuss a stochastic interacting particles’ system connected to dyadic models of turbulence, defining suitable classes of solutions and proving their existence and uniqueness. We investigate the regularity of a particular family of solutions, called moderate, and we conclude with existence and uniqueness of invariant measures associated with such moderate solutions

    Global regularity for a slightly supercritical hyperdissipative Navier-Stokes system

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    We prove global existence of smooth solutions for a slightly supercritical hyperdissipative Navier--Stokes under the optimal condition on the correction to the dissipation. This proves a conjecture formulated by Tao [Tao2009]

    Global regularity for a logarithmically supercritical hyperdissipative dyadic equation

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    We prove global existence of smooth solutions for a slightly supercritical dyadic model. We consider a generalized version of the dyadic model introduced by Katz-Pavlovic [KatPav2004] and add a viscosity term with critical exponent and a supercritical correction. This model catches for the dyadic a conjecture that for Navier-Stokes equations was formulated by Tao [Tao2009

    COTAN : ScRNA-seq data analysis based on gene co-expression

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    Estimating the co-expression of cell identity factors in single-cell is crucial. Due to the low efficiency of scRNA-seq methodologies, sensitive computational approaches are critical to accurately infer transcription profiles in a cell population. We introduce COTAN, a statistical and computational method, to analyze the co-expression of gene pairs at single cell level, providing the foundation for single-cell gene interactome analysis. The basic idea is studying the zero UMI counts' distribution instead of focusing on positive counts; this is done with a generalized contingency tables framework. COTAN can assess the correlated or anti-correlated expression of gene pairs, providing a new correlation index with an approximate p-value for the associated test of independence. COTAN can evaluate whether single genes are differentially expressed, scoring them with a newly defined global differentiation index. Similarly to correlation network analysis, it provides ways to plot and cluster genes according to their co-expression pattern with other genes, effectively helping the study of gene interactions, becoming a new tool to identify cell-identity markers. We assayed COTAN on two neural development datasets with very promising results. COTAN is an R package that complements the traditional single cell RNA-seq analysis and it is available at https://github.com/seriph78/COTAN

    From wheat sourdough to gluten-free sourdough: a conventional process for producing gluten-free bread

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    Gluten-free (GF) sourdough was prepared from wheat sourdough and analysed both in fresh (GFS) and dried forms (DGFS). The gluten content in each GF sourdough sample was <20mgkg(-1). The dough leavening capacity and the properties of the bread samples were investigated and compared to those of bread prepared using bakery yeast (Saccharomyces cerevisiae). Two commercial rice-based mixtures (different for the presence/absence of buckwheat flour) were used to prepare bread samples. In GFS, lactic acid bacteria (LAB) and yeasts were found in amounts corresponding to 10(8) and 10(7) CFUg(-1), respectively, whereas both LAB and yeasts were detected in lower amounts (about 10(6) CFUg(-1)) in DGFS. When used in bread-making, both GFS types produced significant dough acidification and exhibited good dough development during proofing, resulting in loaves with specific volume values between 3.00 and 4.12mLg(-1), values similar to those obtained for reference bread (3.05 divided by 4.15mLg(-1)). The use of GFS was effective in lowering the bread staling rate during storage for up to 7days

    SAI: A sensible artificial intelligence that plays with handicap and targets high scores in 9x9 Go

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    We develop a new framework for the game of Go to target a high score, and thus a perfect play. We integrate this framework into the Monte Carlo tree search - policy iteration learning pipeline introduced by Google DeepMind with AlphaGo. Training on 9Ă—9 Go produces a superhuman Go player, thus proving that this framework is stable and robust. We show that this player can be used to effectively play with both positional and score handicap. We develop a family of agents that can target high scores against any opponent, recover from very severe disadvantage against weak opponents, and avoid suboptimal moves

    Wheat germ stabilization by heat-treatment or sourdough fermentation: effects on dough rheology and bread properties

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    The aim of this work was to evaluate the effects of wheat germ - stabilized by toasting or by sourdough fermentation - on dough and bread properties. Doughs were produced by adding increasing amounts of each type of stabilized germ, starting with the current recommended level of 3 g/100 g up to 20 g/100 g. Sourdough fermentation ensured the presence of lactic acid bacteria (LAB) in amounts comparable to those found in conventional sourdough. The acidification induced by LAB inactivates lipase and lipoxygenase, as does the toasting process. These results account for the decrease in rancidity, as demonstrated by the low development of hexanal during storage. Fermentation significantly decreased the content of glutathione, responsible for the deterioration of the rheological characteristics and workability of dough containing high levels of germ. Dough enriched with fermented germ exhibited high stability during mixing and development. Positive effects (high specific volume and low firmness) associated with the use of germ stabilized by fermentation have been detected both in fresh bread and in samples stored up to 4 days in controlled conditions of humidity and temperature. Finally, the sensory consumers' test confirmed that the addition of fermented germ did not diminish the liking of the sample

    Hedgerows enhance beneficial insects on adjacent tomato fields in an intensive agricultural landscape

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    Within-farm habitat enhancements such as hedgerows could aid pest control in adjacent crops; however, there is little information on whether small-scale restoration impacts pests and natural enemies, and crop damage, and how far effects may extend into fields. We compared restored, California native perennial hedgerows to unenhanced field edges consisting of commonly occurring semi-managed, non-native weeds. Pest and natural enemy communities were assessed in both edge types and into adjacent processing tomato fields. Using sentinel pest eggs, pest control was quantified, and pest pressure and crop damage was compared between field types. Economically-important pests were fewer and parasitoid wasps were more abundant in hedgerows than weedy crop edges. There was no difference in predatory arthropod abundance between edge types, but there was greater predator richness in hedgerow than weedy edges. Predatory lady beetles were more abundant and aphids were lower in fields with hedgerows, up to 200. m into fields, the maximum extent of observations. Fewer of the fields adjacent to hedgerows reached threshold pest levels requiring insecticide application. Benefits of hedgerows to pest control from parasitism extended to 100. m but not 200. m into fields. Farm-scale hedgerow restoration can provide pest control benefits up to 100 or 200. m into fields and multiple hedgerows around fields could enhance pest control throughout entire fields, reducing the need for chemical pest control. © 2014 Published by Elsevier B.V
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