6,518 research outputs found

    A Radical FLP Approach to C–C Coupling

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    In the February issue of Cell Reports Physical Science, Melen and co-workers report the reactivity of diaryl-substituted esters with R3P/B(C6F5)3 frustrated Lewis pairs (FLPs). Although ester C–O activation occurs for all FLP systems, the use of Mes3P induces single-electron transfer to generate a [Mes3P]⋅+/[C(H)Ar2]⋅ radical ion pair. In the presence of olefins, this reactivity is harnessed in an sp2-sp3 C–C heterocoupling reaction to generate α,β-substituted olefins.</p

    RNA interference in marine and freshwater sponges

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    Background: The marine sponge Tethya wilhelma and the freshwater sponge Ephydatia muelleri are emerging model organisms to study evolution, gene regulation, development, and physiology in non-bilaterian animal systems. Thus far, functional methods (i.e., loss or gain of function) for these organisms have not been available. Results: We show that soaking developing freshwater sponges in double-stranded RNA and/or feeding marine and freshwater sponges bacteria expressing double-stranded RNA can lead to RNA interference and reduction of targeted transcript levels. These methods, first utilized in C. elegans, have been adapted for the development and feeding style of easily cultured marine and freshwater poriferans. We demonstrate phenotypic changes result from ‘knocking down’ expression of the actin gene. Conclusion: This technique provides an easy, efficient loss-of-function manipulation for developmental and gene regulatory studies in these important non-bilaterian animals

    Multimetallic Alkaline-Earth Hydride Cations

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    Reactions of dimeric β-diketiminato (BDI) magnesium and calcium hydrides with [(BDI)Mg]+[Al{OC(CF3)3}4]- provide ionic multimetallic hydride derivatives, which have been characterized by single-crystal X-ray diffraction analysis. The exclusively magnesium centered species comprises a cation in which two [(BDI)Mg]+ units are connected by a single μ2-bridging hydride. In contrast, the greater lability of the calcium-containing system is underscored by the isolation of a cyclic heterotrimetallic species in which a CaH2 moiety is coordinated by a molecule of benzene and an aryl substituent of a [{(BDI)Mg}2H]+ cation. The homometallic dimagnesium species displays a greater facility toward reaction with diphenylacetylene than neutral [(BDI)MgH]2, although the resultant crystallographically characterized vinyldimagnesium cation equilibrates into a complex mixture of neutral and ionic species in solution. An initial assessment of both systems for the hydrosilylation of 1-hexene and diphenylacetylene evidences an inferior catalytic performance of [(BDI)MgH]2 in isolation.</p

    Multimetallic Alkaline-Earth Hydride Cations

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    Reactions of dimeric β-diketiminato (BDI) magnesium and calcium hydrides with [(BDI)Mg]+[Al{OC(CF3)3}4]- provide ionic multimetallic hydride derivatives, which have been characterized by single-crystal X-ray diffraction analysis. The exclusively magnesium centered species comprises a cation in which two [(BDI)Mg]+ units are connected by a single μ2-bridging hydride. In contrast, the greater lability of the calcium-containing system is underscored by the isolation of a cyclic heterotrimetallic species in which a CaH2 moiety is coordinated by a molecule of benzene and an aryl substituent of a [{(BDI)Mg}2H]+ cation. The homometallic dimagnesium species displays a greater facility toward reaction with diphenylacetylene than neutral [(BDI)MgH]2, although the resultant crystallographically characterized vinyldimagnesium cation equilibrates into a complex mixture of neutral and ionic species in solution. An initial assessment of both systems for the hydrosilylation of 1-hexene and diphenylacetylene evidences an inferior catalytic performance of [(BDI)MgH]2 in isolation.</p

    Traumatic Axonal Injury: Mechanisms and Translational Opportunities.

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    Traumatic axonal injury (TAI) is an important pathoanatomical subgroup of traumatic brain injury (TBI) and a major driver of mortality and functional impairment. Experimental models have provided insights into the effects of mechanical deformation on the neuronal cytoskeleton and the subsequent processes that drive axonal injury. There is also increasing recognition that axonal or white matter loss may progress for years post-injury and represent one mechanistic framework for progressive neurodegeneration after TBI. Previous trials of novel therapies have failed to make an impact on clinical outcome, in both TBI in general and TAI in particular. Recent advances in understanding the cellular and molecular mechanisms of injury have the potential to translate into novel therapeutic targets.CSH is supported by a Wellcome Trust PhD for Clinicians. MPC is funded by the John and Lucille van Geest Foundation. DKM is supported by a Senior Investigator Award from the National Institute for Health Research, UK (NIHR), by the Acute Brain Injury and Repair theme of the Cambridge NIHR Biomedical Research Centre, and a Framework Program 7 grant from the European Union (CENTER-TBI; Grant No: 602150)This is the final version of the article. It first appeared from Elsevier via https://doi.org/ 10.1016/j.tins.2016.03.00

    A haplome alignment and reference sequence of the highly polymorphic Ciona savignyi genome

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    The high degree of polymorphism in the genome of the sea squirt Ciona savignyi complicated the assembly of sequence contigs, but a new alignment method results in a much improved sequence

    Group treatments for sensitive health care problems : a randomised controlled trial of group versus individual physiotherapy sessions for female urinary incontinence

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    Background: The aim was to compare effectiveness of group versus individual sessions of physiotherapy in terms of symptoms, quality of life, and costs, and to investigate the effect of patient preference on uptake and outcome of treatment. Methods: A pragmatic, multi-centre randomised controlled trial in five British National Health Service physiotherapy departments. 174 women with stress and/or urge incontinence were randomised to receive treatment from a physiotherapist delivered in a group or individual setting over three weekly sessions. Outcome were measured as Symptom Severity Index; Incontinence-related Quality of Life questionnaire; National Health Service costs, and out of pocket expenses. Results: The majority of women expressed no preference (55%) or preference for individual treatment (36%). Treatment attendance was good, with similar attendance with both service delivery models. Overall, there were no statistically significant differences in symptom severity or quality of life outcomes between the models. Over 85% of women reported a subjective benefit of treatment, with a slightly higher rating in the individual compared with the group setting. When all health care costs were considered, average cost per patient was lower for group sessions (Mean cost difference £52.91 95%, confidence interval (£25.82 - £80.00)). Conclusion: Indications are that whilst some women may have an initial preference for individual treatment, there are no substantial differences in the symptom, quality of life outcomes or non-attendance. Because of the significant difference in mean cost, group treatment is recommended

    Facile kinetic induction of a dihydropyridide to pyrrolide ring contraction

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    A sterically demanding N-aryl carbodiimide reacts with magnesium 1,4-dihydropyridides to initiate heterocyclic ring contraction and pyrrolide formation under unprecedentedly mild conditions.</p

    Heasim and Skyback Simulation Tools and Their Application to the Hitomi Mission

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    We present an introduction to the heasim multimission observation and skyback background, high-energy pseudo Monte Carlo astrophysical simulation tools. Heasim may be used to accurately and efficiently construct flexible image transport system (FITS) event files for simple or composite sources with a wide range of standard and user-defined spatial, spectral, and temporal characteristics. Skyback is designed to enable users to assess the impact of background discrete and diffuse emission on prospective observations, and skyback output may be directly input into heasim. We present a brief overview of heasim and skyback input, algorithms, usage, and output. We also introduce the sxsbranch tool that computes Hitomi soft X-ray spectrometer resolution grade branching ratios, emphasizing its application to simulations. We include several examples of particular relevance to the Hitomi mission

    The Ultraviolet Imaging Telescope: Instrument and Data Characteristics

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    The Ultraviolet Imaging Telescope (UIT) was flown as part of the Astro observatory on the Space Shuttle Columbia in December 1990 and again on the Space Shuttle Endeavor in March 1995. Ultraviolet (1200-3300 Angstroms) images of a variety of astronomical objects, with a 40 arcmin field of view and a resolution of about 3 arcsec, were recorded on photographic film. The data recorded during the first flight are available to the astronomical community through the National Space Science Data Center (NSSDC); the data recorded during the second flight will soon be available as well. This paper discusses in detail the design, operation, data reduction, and calibration of UIT, providing the user of the data with information for understanding and using the data. It also provides guidelines for analyzing other astronomical imagery made with image intensifiers and photographic film.Comment: 44 pages, LaTeX, AAS preprint style and EPSF macros, accepted by PAS
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