398 research outputs found

    Immune function and parasite resistance in male and polymorphic female Coenagrion puella

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    Background: Colour polymorphisms are widespread and one of the prime examples is the colour polymorphism in female coenagrionid damselflies: one female morph resembles the male colour (andromorph) while one, or more, female morphs are described as typically female (gynomorph). However, the selective pressures leading to the evolution and maintenance of this polymorphism are not clear. Here, based on the hypothesis that coloration and especially black patterning can be related to resistance against pathogens, we investigated the differences in immune function and parasite resistance between the different female morphs and males. Results: Our studies of immune function revealed no differences in immune function between the female morphs but between the sexes in adult damselflies. In an experimental infection females infected shortly after emergence showed a higher resistance against a fungal pathogen than males, however female morphs did not differ in resistance. In a field sample of adult damselflies we did not find differences in infection rates with watermites and gregarines. Conclusion: With respect to resistance and immune function 'andromorph' blue females of Coenagrion puella do not resemble the males. Therefore the colour polymorphism in coenagrionid damselflies is unlikely to be maintained by differences in immunity

    Reify Your Collection Queries for Modularity and Speed!

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    Modularity and efficiency are often contradicting requirements, such that programers have to trade one for the other. We analyze this dilemma in the context of programs operating on collections. Performance-critical code using collections need often to be hand-optimized, leading to non-modular, brittle, and redundant code. In principle, this dilemma could be avoided by automatic collection-specific optimizations, such as fusion of collection traversals, usage of indexing, or reordering of filters. Unfortunately, it is not obvious how to encode such optimizations in terms of ordinary collection APIs, because the program operating on the collections is not reified and hence cannot be analyzed. We propose SQuOpt, the Scala Query Optimizer--a deep embedding of the Scala collections API that allows such analyses and optimizations to be defined and executed within Scala, without relying on external tools or compiler extensions. SQuOpt provides the same "look and feel" (syntax and static typing guarantees) as the standard collections API. We evaluate SQuOpt by re-implementing several code analyses of the Findbugs tool using SQuOpt, show average speedups of 12x with a maximum of 12800x and hence demonstrate that SQuOpt can reconcile modularity and efficiency in real-world applications.Comment: 20 page

    Harnessing the ambiphilicity of silyl nitronates in a catalytic asymmetric approach to aliphatic β<sup>3</sup>-amino acids

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    Nitronate anions, formally generated by α-deprotonating the corresponding nitroalkanes, are highly nucleophilic and versatile intermediates in many carbon–carbon bond-forming reactions. In contrast, the corresponding silyl nitronates are ambiphilic and react, at the same carbon atom, with both electrophiles and nucleophiles. However, while their nucleophilicity has been well exploited in catalytic enantioselective reactions with imines and aldehydes, utilizing the electrophilicity of silyl nitronates in asymmetric synthesis has remained elusive. Here we report the facile, efficient and general reactivity of readily available silyl nitronates with silyl ketene acetals, catalysed by highly Lewis-acidic and confined silylium imidodiphosphorimidate catalysts. The products of this reaction, so-called nitroso acetals, are obtained in excellent enantioselectivity and can be easily converted into N-Boc-β3-amino acid esters in a single step

    Switching dynamics of spatial solitary wave pixels

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    Separatrices and scaling laws in the switching dynamics of spatial solitary wave pixels are investigated. We show that the dynamics in the full model are similar to those in the plane-wave limit. Switching features may be indicated and explained by the motion of the (complex) solitary wave amplitude in the phase plane. We report generalization, into the domain of transverse effects, of the pulse area theorem for the switching process and a logarithmic law for the transient dynamics. We also consider, for what is the first time to our knowledge, phase-encoded address of solitary pixels and find that a near-square-wave temporal switching pattern is permitted without (transverse) cross switching

    Conservation Laws in Higher-Order Nonlinear Optical Effects

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    Conservation laws of the nonlinear Schr\"{o}dinger equation are studied in the presence of higher-order nonlinear optical effects including the third-order dispersion and the self-steepening. In a context of group theory, we derive a general expression for infinitely many conserved currents and charges of the coupled higher-order nonlinear Schr\"{o}dinger equation. The first few currents and charges are also presented explicitly. Due to the higher-order effects, conservation laws of the nonlinear Schr\"{o}dinger equation are violated in general. The differences between the types of the conserved currents for the Hirota and the Sasa-Satsuma equations imply that the higher-order terms determine the inherent types of conserved quantities for each integrable cases of the higher-order nonlinear Schr\"{o}dinger equation

    Optical Solitary Waves in the Higher Order Nonlinear Schrodinger Equation

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    We study solitary wave solutions of the higher order nonlinear Schrodinger equation for the propagation of short light pulses in an optical fiber. Using a scaling transformation we reduce the equation to a two-parameter canonical form. Solitary wave (1-soliton) solutions exist provided easily met inequality constraints on the parameters in the equation are satisfied. Conditions for the existence of N-soliton solutions (N>1) are determined; when these conditions are met the equation becomes the modified KdV equation. A proper subset of these conditions meet the Painleve plausibility conditions for integrability.Comment: REVTeX, 4 pages, no figures. To appear in Phys. Rev. Let

    Sviluppo di tecniche di simulazione eterogenea funzionale e numerica applicate all’ingegneria di sistemi aeronautici

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    Questo studio illustra l’impiego del ‘Model Based Systems Engineering’ (MBSE), in cui strumenti di modellazione funzionale si integrano con modelli numerici, da tempo impiegati in progettazione, per la realizzazione di sistemi complessi. E’ analizzato un sistema antighiaccio aeronautico, sviluppato nell’ambito del progetto ‘CRYSTAL’. L’obiettivo è stato raggiunto collegando il gestore di requisiti IBM DOORS®, IBM RHAPSODY®, che opera in ambiente SysML, e SIMULINK® o DYMOLA®. L’interoperabilità è stata garantita dallo standard di connessione Functional Mock–up Interface (FMI), che ha permesso di validare il processo realizzando la cosiddetta ‘simulazione eterogenea’ di modelli funzionali e numerici integrati

    Heat-Shock Protein 90 Controls the Expression of Cell-Cycle Genes by Stabilizing Metazoan-Specific Host-Cell Factor HCFC1

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    Molecular chaperones such as heat-shock proteins (HSPs) help in protein folding. Their function in the cytosol has been well studied. Notably, chaperones are also present in the nucleus, a compartment where proteins enter after completing de novo folding in the cytosol, and this raises an important question about chaperone function in the nucleus. We performed a systematic analysis of the nuclear pool of heat-shock protein 90. Three orthogonal and independent analyses led us to the core functional interactome of HSP90. Computational and biochemical analyses identify host cell factor C1 (HCFC1) as a transcriptional regulator that depends on HSP90 for its stability. HSP90 was required to maintain the expression of HCFC1-targeted cell-cycle genes. The regulatory nexus between HSP90 and the HCFC1 module identified in this study sheds light on the relevance of chaperones in the transcription of cell-cycle genes. Our study also suggests a therapeutic avenue of combining chaperone and transcription inhibitors for cancer treatment
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