5,260 research outputs found

    Increased levels of RNA oxidation enhance the reversion frequency in aging pro-apoptotic yeast mutants

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    Despite recent advances in understanding the complexity of RNA processes, regulation of the metabolism of oxidized cellular RNAs and the mechanisms through which oxidized ribonucleotides affect mRNA translation, and consequently cell viability, are not well characterized. We show here that the level of oxidized RNAs is markedly increased in a yeast decapping Kllsm4Δ1 mutant, which accumulates mRNAs, ages much faster that the wild type strain and undergoes regulated-cell-death. We also found that in Kllsm4Δ1 cells the mutation rate increases during chronological life span indicating that the capacity to han- dle oxidized RNAs in yeast declines with aging. Lowering intracellular ROS levels by antioxidants recovers the wild- type phenotype of mutant cells, including reduced amount of oxidized RNAs and lower mutation rate. Since mRNA oxidation was reported to occur in different neurodegen- erative diseases, decapping-deficient cells may represent a useful tool for deciphering molecular mechanisms of cell response to such conditions, providing new insights into RNA modification-based pathogenesis

    Structural aspects of the female sexual differentiation of the pirarucu (Arapaima gigas, SCHINZ, 1822).

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    The pirarucu (Arapaima gigas) are the biggest scale Amazonian fish and their farming potential is enormous. However, there are few studies involving the reproductive physiology of pirarucu. Raising fish in confined environments still encounters several adversities, being necessary basic studies for the development of the productive chain, mainly at the early stages of development. Thus, studies related to the gonadal development are essential for the understanding of the reproductive biology of the species

    A device to characterize optical fibres

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    ATLAS is a general purpose experiment approved for the LHC collider at CERN. An important component of the detector is the central hadronic calorimeter; for its construction more than 600,000 Wave Length Shifting (WLS) fibres (corresponding to a total length of 1,120 Km) have been used. We have built and put into operation a dedicated instrument for the measurement of light yield and attenuation length over groups of 20 fibres at a time. The overall accuracy achieved in the measurement of light yield (attenuation length) is 1.5% (3%). We also report the results obtained using this method in the quality control of a large sample of fibres.Comment: 17 pages 20 figeres submitted to NIM journa

    Analytical and Numerical Characterization of Cherenkov Diffraction Radiation as a Longitudinal Electron Bunch Profile Monitor for AWAKE Run 2

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    In this paper, CST simulations of the coherent Cherenkov Diffraction Radiation with a range of parameters for different dielectric target materials and geometries are discussed and compared with the theoretical investigation of the Polarization Current Approach to design a prototype of a radiator for the bunch length/profile monitor for AWAKE Run 2. It was found that the result of PCA theory and CST simulation are consistent with each other regarding the shape of the emitted ChDR cone

    Optimization Study of Beam Position and Angular Jitter Independent Bunch Length Monitor for Awake Run 2

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    In this paper, a study using the Polarization Current Approach (PCA) model is performed to optimize the design of a short bunch length monitor using two dielectric radiators that produce coherent Cherenkov Diffraction Radiation (ChDR). The electromagnetic power emitted from each radiator is measuring a different part of the bunch spectrum using Schottky diodes. For various bunch lengths, the coherent ChDR spectrums are calculated to find the most suitable frequency bands for the detection system. ChDR intensities measured by each detector are estimated for different impact parameters to explore the dependence of bunch length monitor on beam position and angular jitter. It is found that, in the present configuration, the effects of beam position and angular jitter are negligibly small for bunch length measurement

    Electron bunch position determination using a high frequency button beam position monitor in the AWAKE facility

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    The AWAKE facility uses novel proton beam-driven plasma wakefields to accelerate electron bunches over 10 m of Rubidium plasma. Precise monitoring of 2 diverse beam types necessitates an electron beam position monitor (BPM) working in a frequency regime of tens of GHz. A high frequency conical button-style BPM with a working regime of up to 40 GHz has been investigated as a way to discriminate the electromagnetic fields of 19 MeV, 4 ps electron bunches propagating spatially and temporally together with a 400 GeV, 170 ps proton bunch in the AWAKE common beamline. The sensitivity of the HF BPM to the electron beam position is determined under various beam conditions, with both electrons and protons, and integration with a TRIUMF front-end is discussed

    Beam studies using a Cherenkov diffraction based beam position monitor for AWAKE

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    A beam position monitor based on Cherenkov diffraction radiation (ChDR) is being investigated as a way to disentangle the signals generated by the electromagnetic fields of a short-pulse electron bunch from a long proton bunch co-propagating in the AWAKE plasma acceleration experiment at CERN. These ChDR BPMs have undergone renewed testing under a variety of beam conditions with proton and electron bunches in the AWAKE common beamline, at 3 different frequency ranges between 20-110 GHz to quantify the effectiveness of discriminating the electron beam position with and without proton bunches present. These results indicate an increased sensitivity to the electron beam position in the highest frequency bands. Furthermore, high frequency studies investigating the proton bunch spectrum show that a much higher frequency regime is needed to exclude the proton signal than previously expected

    Measuring and explaining the diversity of voices and viewpoints in the news

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    News media can be considered to fulfil their democratic role as a “marketplace of ideas” only if they present a diverse content that gives space to a wider range of ideas and viewpoints. But how can content diversity be assessed? And what determines actor and viewpoint diversity in the first place? By employing measurements of actor and viewpoint diversity at the article and newspaper level, this study provides a complete overview on the content diversity of immigration news, and it investigates factors that have an impact on content diversity of immigration newspaper articles in Belgium, Germany, Italy and the United Kingdom (2013-2014). The results of a multilevel analysis indicate that both the articles’ size and the elite character of a newspaper play a key role in enhancing news’ multiperspectivalness. Also, the findings show that these two measurements of content diversity are different yet related to each other

    Demography and selection shape transcriptomic divergence in field crickets

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    Gene flow, demography, and selection can result in similar patterns of genomic variation and disentangling their effects is key to understanding speciation. Here, we assess transcriptomic variation to unravel the evolutionary history of Gryllus rubens and Gryllus texensis, cryptic field cricket species with highly divergent mating behavior. We infer their demographic history and screen their transcriptomes for footprints of selection in the context of the inferred demography. We find strong support for a long history of bidirectional gene flow, which ceased during the late Pleistocene, and a bottleneck in G. rubens consistent with a peripatric origin of this species. Importantly, the demographic history has likely strongly shaped patterns of genetic differentiation (empirical F-ST distribution). Concordantly, F-ST-based selection detection uncovers a large number of outliers, likely comprising many false positives, echoing recent theoretical insights. Alternative genetic signatures of positive selection, informed by the demographic history of the sibling species, highlighted a smaller set of loci; many of these are candidates for controlling variation in mating behavior. Our results underscore the importance of demography in shaping overall patterns of genetic divergence and highlight that examining both demography and selection facilitates a more complete understanding of genetic divergence during speciation

    The incidence and intensity of postendodontic pain and flareup in single and multiple visit root canal treatments: a systematic review and meta-analysis

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    To assess the incidence and intensity of postendodontic pain and flareup in single and multiple visit root canal treatment (RCT) and determine if the difference between the two is significant, a search of PubMed, Medline, Embase, Cochrane, Scopus and Web of science was conducted. The grey literature was searched using Google Scholar and Saudi digital library. Randomised controlled trials evaluating the incidence and intensity of postendodontic pain and flareup published in English from 1 January 2000 to 15 April 2020 were searched. The PRISMA protocol was followed to select the articles. A random effects model was used for the meta-analysis of the data in the included studies. Twenty-one articles were included in the review. Three compared both the incidence and the intensity, while the rest compared either one of the parameters. Most studies used both hand-driven and rotary instruments and irrigated with sodium hypochlorite. Twelve studies used an intracanal medicament. Although individual studies showed discordant treatment outcomes, the meta-analysis did not reveal any significant difference in the incidence or the intensity of the postendodontic flareup between the single and multiple visit RCT groups. Single or a multiple visit root canal treatment is not an independent determinant for the risk of postendodontic pain or a flareup
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