387 research outputs found

    Resummation of perturbation series and reducibility for Bryuno skew-product flows

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    We consider skew-product systems on T^d x SL(2,R) for Bryuno base flows close to constant coefficients, depending on a parameter, in any dimension d, and we prove reducibility for a large measure set of values of the parameter. The proof is based on a resummation procedure of the formal power series for the conjugation, and uses techniques of renormalisation group in quantum field theory.Comment: 30 pages, 12 figure

    Nutrient Considerations for Plants Grown Under Space Flight Conditions

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    We present here results on the analysis of 100 mL medium samples extracted from sterilized foam (Smithers-Oasis, Kent OH) used to support the growth of both dicotyledonous (Haplopappus gracilis, n=75) and monocotyledonous (Hemerocallis cv Autumn Blaze, n=25) aseptic plants in NASA's Plant Growth Unit (PGU) during the 5-day CHROMEX-01 Space Shuttle flight (March 1989, STS-29). At recovery, the medium remaining within each of the five floral foam blocks (for both the space flight and ground control experiments) was extracted under vacuum, filtered and subjected to elemental analyses. Concentration levels of some elements remained the same, while some decreased and others increased. A unique aspect of this experiment was that all plants were either aseptic tissue culture generated plantlets or sterile seedling clones, and the design of the PGU facilitated the maintenance of asepsis throughout the mission (confirmed by postflight microbial sampling). This permitted the elimination of microbial considerations in the interpretation of the data. The significance of these findings for growing plants in altered gravity environments are discussed

    Microfilaments and actin-associated proteins at sites of membrane-substrate attachment within acetylcholine receptor clusters

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    Rat myotubes in tissue culture form broad areas of close contact with the substrate. These areas often display two distinct, interdigitating sets of membrane domains. One, the "contact domain", is close to the substrate; the other, termed the "AChR domain", is further from the substrate and is rich in acetylcholine receptors (AChR). We have used fluorescence techniques to study the organization of the cytoskeleton in these areas. Substrate-apposed membrane of the myotubes was exposed either by shearing or by permeabilizing the cells with a neutral detergent. Phalloidin derivatives and affinity-purified polyclonal or monoclonal antibodies specific for cytoskeletal proteins were then applied to the samples. Sheared samples were observed by epifluorescence microscopy; detergent-permeabilized samples were observed by total internal reflection fluorescence microscopy. We found that, like antivinculin, fluorescent phalloidin derivatives and antibodies to [alpha]-actinin, filamin, and talin preferentially labeled the contact domains. This suggests that bundles of microfilaments associate with the membrane at sites of myotubesubstrate attachment. In contrast, a 43K protein, closely associated with AChR, was present only at AChR domains. A monoclonal antibody to actin labeled both AChR and contact domains, suggesting that actin is enriched over both regions. Our results suggest that, like the plasma membrane of AChR clusters, the underlying membrane skeleton is organized into at least two distinct domains.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/27926/1/0000350.pd

    Growth and Photosynthetic Responses of Wheat Plants Grown in Space

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    A Nonperturbative Eliasson's Reducibility Theorem

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    This paper is concerned with discrete, one-dimensional Schr\"odinger operators with real analytic potentials and one Diophantine frequency. Using localization and duality we show that almost every point in the spectrum admits a quasi-periodic Bloch wave if the potential is smaller than a certain constant which does not depend on the precise Diophantine conditions. The associated first-order system, a quasi-periodic skew-product, is shown to be reducible for almost all values of the energy. This is a partial nonperturbative generalization of a reducibility theorem by Eliasson. We also extend nonperturbatively the genericity of Cantor spectrum for these Schr\"odinger operators. Finally we prove that in our setting, Cantor spectrum implies the existence of a GδG_\delta-set of energies whose Schr\"odinger cocycle is not reducible to constant coefficients

    Global dynamics of three species omnivory models with Lotka-Volterra interaction

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    [[abstract]]In this work, we consider the community of three species food web model with Lotka-Volterra type predator-prey interaction. In the absence of other species, each species follows the traditional logistical growth model and the top predator is an omnivore which is defined as feeding on the other two species. It can be seen as a model with one basal resource and two generalist predators, and pairwise interactions of all species are predator-prey type. It is well known that the omnivory module blends the attributes of several well-studied community modules, such as food chains (food chain models), exploitative competition (two predators-one prey models), and apparent competition (one predator-two preys models). With a mild biological restriction, we completely classify all parameters. All local dynamics and most parts of global dynamics are established corresponding to the classification. Moreover, the whole system is uniformly persistent when the unique coexistence appears. Finally, we conclude by discussing the strategy of inferior species to survive and the mechanism of uniform persistence for the three species ecosystem.[[notice]]補正完

    Which executive functioning deficits are associated with AD/HD, ODD/CD and comorbid AD/HD+ODD/CD?

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    Item does not contain fulltextThis study investigated (1) whether attention deficit/hyperactivity disorder (AD/HD) is associated with executive functioning (EF) deficits while controlling for oppositional defiant disorder/conduct disorder (ODD/CD), (2) whether ODD/CD is associated with EF deficits while controlling for AD/HD, and (3)~whether a combination of AD/HD and ODD/CD is associated with EF deficits (and the possibility that there is no association between EF deficits and AD/HD or ODD/CD in isolation). Subjects were 99~children ages 6–12 years. Three putative domains of EF were investigated using well-validated tests: verbal fluency, working memory, and planning. Independent of ODD/CD, AD/HD was associated with deficits in planning and working memory, but not in verbal fluency. Only teacher rated AD/HD, but not parent rated AD/HD, significantly contributed to the prediction of EF task performance. No EF deficits were associated with ODD/CD. The presence of comorbid AD/HD accounts for the EF deficits in children with comorbid AD/HD+ODD/CD. These results suggest that EF deficits are unique to AD/HD and support the model proposed by R. A. Barkley (1997).17 p

    Riding on the Coat-Tails of Traditional Cultural Expressions

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    Matters related to the protection of traditional cultural expressions (‘TCEs’) or expressions of folklore (‘EoFs’) are sensitive and intricate as a blend of legal, economic, philosophical and anthropological considerations jostle to capture their core features. This results in disparate views surrounding what should qualify as TCEs or EoFs, who should be considered their ‘owner’ (assuming that ownership per se is conceptually compatible with these items), which is the most appropriate legal protection regime and how broad their scope of protection should be. Drawing from these various accounts on TCEs, this article focuses on the interaction between TCEs and EoFs originating on the European continent and the European Union (‘EU’) trade mark legislation. Specifically, this article examines whether the limitations of the effects of trade mark rights and of the absolute grounds of refusal, as developed by the case law of the Court of Justice of the European Union, are effective in preserving the cohesion of TCEs. This article advances the thesis that registration of TCEs and EoFs as trade marks generates an imbalance between the rights of the trade mark owner and the defences available to others under the EU trade mark law framework. Furthermore, such an imbalance is likely to hinder the unfettered circulation of TCEs and undermine their original meaning. Lastly, in some cases, trade mark registration of TCEs contributes to their appropriation and misappropriation. The article concludes that, de lege ferenda, the direct exclusion of TCEs as eligible subject matter for trade mark registration is preferable to seeking a post factum remedy
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