1,900 research outputs found

    On the vacancy decay in endohedral atoms

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    It is demonstrated that the fullerene shell affects dramatically the radiative and Auger vacancy decay of an endohedral atom A@C60. The collectivized electrons of the C60 shell add new possibilities for radiative and non-radiative decays similar to that in ordinary atoms where initial and final state vacancies almost always belong to different subshells. It is shown that the smallness of the atomic shell radii as compared to that of the fullerenes shell provides an opportunity to derive the simple formulas for the probabilities of the electron transitions. It is shown that the radiative and Auger (or Koster-Kronig) widths of a vacancy decay due to electron transition in the atom A in A@C60 acquire an additional factors that can be expressed via the polarizability of the C60 at transition energy. It is demonstrated that due to opening of the non-radiative decay channel for vacancies in subvalent subshells the decay probability increases by five -- six orders of magnitude.Comment: 14 pages, 4 figure

    Pluri-Canonical Models of Supersymmetric Curves

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    This paper is about pluri-canonical models of supersymmetric (susy) curves. Susy curves are generalisations of Riemann surfaces in the realm of super geometry. Their moduli space is a key object in supersymmetric string theory. We study the pluri-canonical models of a susy curve, and we make some considerations about Hilbert schemes and moduli spaces of susy curves.Comment: To appear in the proceedings of the intensive period "Perspectives in Lie Algebras", held at the CRM Ennio De Giorgi, Pisa, Italy, 201

    Preparation for the measurement of the bound-state beta-decay of bare 205Tl ions at the ESR

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    Bound-state beta-decay (βb) accompanied by the emission of a monochromatic antineutrino, was first predicted by Daudel et al [1] in 1947 and then discussed in detail by Bahcall [2]. The first direct observation of the bound-state beta decay (βb decay) was done in 1992 by Jung et al [3] with the use of bare 163Dy66+ ions stored in the heavy ion storage ring ESR at GSI. In the present study we aim at measuring the bound-state beta-decay rate of fully-ionized 205Tl, which is needed to determine the matrix element for the electron capture decay from the 2.3 keV excited state in 205Pb to the ground state of 205Tl. This matrix element is important for constraining of neutrino capture probability into the 2.3 keV state of 205Pb [4] and for modelling of the s-process [5] in the Hg-Pb region. The experiment proposal has been approved by the GSI program advisory panel. We aim at conducting the experiment in 2018, when the accelerator complex of GSI will restart its operatio

    Neutron detection in the SNO+ water phase

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    SNO+ is a multipurpose neutrino experiment located approximately 2 km underground in SNOLAB, Sudbury, Canada. The detector started taking physics data in May 2017 and is currently completing its first phase, as a pure water Cherenkov detector. The low trigger threshold of the SNO+ detector allows for a substantial neutron detection efficiency, as observed with a deployed ^{241}Am^{9}Be source. Using a statistical analysis of one hour AmBe calibration data, we report a neutron capture constant of 208.2 + 2.1(stat.) us and a lower bound of the neutron detection efficiency of 46% at the center of the detector.Peer Reviewe

    A defect in myoblast fusion underlies Carey-Fineman-Ziter syndrome

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    Multinucleate cellular syncytial formation is a hallmark of skeletal muscle differentiation. Myomaker, encoded by Mymk (Tmem8c), is a well-conserved plasma membrane protein required for myoblast fusion to form multinucleated myotubes in mouse, chick, and zebrafish. Here, we report that autosomal recessive mutations in MYMK (OMIM 615345) cause Carey-Fineman-Ziter syndrome in humans (CFZS; OMIM 254940) by reducing but not eliminating MYMK function. We characterize MYMK-CFZS as a congenital myopathy with marked facial weakness and additional clinical and pathologic features that distinguish it from other congenital neuromuscular syndromes. We show that a heterologous cell fusion assay in vitro and allelic complementation experiments in mymk knockdown and mymkinsT/insT zebrafish in vivocan differentiate between MYMK wild type, hypomorphic and null alleles. Collectively, these data establish that MYMK activity is necessary for normal muscle development and maintenance in humans, and expand the spectrum of congenital myopathies to include cell-cell fusion deficits

    Incidence and Risk Factors for Clinically Confirmed secondary bacterial infections in patients hospitalized for coronavirus disease 2019 (COVID-19)

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    Objective: The true incidence and risk factors for secondary bacterial infections in coronavirus disease 2019 (COVID-19) remains poorly understood. Knowledge of risk factors for secondary infections in hospitalized patients with COVID-19 is necessary to optimally guide selective use of empiric antimicrobial therapy. Design: Single-center retrospective cohort study of symptomatic inpatients admitted for COVID-19 from April 15, 2020, through June 30, 2021. Setting: Academic quaternary-care referral center in Portland, Oregon. Patients: The study included patients who were 18 years or older with a positive severe acute respiratory coronavirus virus 2 (SARS-CoV-2) PCR test up to 10 days prior to admission. Methods: Secondary infections were identified based on clinical, radiographic, and microbiologic data. Logistic regression was used to identify risk factors for secondary infection. We also assessed mortality, length of stay, and empiric antibiotics among those with and without secondary infections. Results: We identified 118 patients for inclusion; 31 (26.3%) had either culture-proven or possible secondary infections among hospitalized patients with COVID-19. Mortality was higher among patients with secondary infections (35.5%) compared to those without secondary infection (4.6%). Empiric antibiotic use on admission was high in both the secondary and no secondary infection groups at 71.0% and 48.3%, respectively. Conclusions: The incidence of secondary bacterial infection was moderate among hospitalized patients with COVID-19. However, a higher proportion of patients received empiric antibiotics regardless of an identifiable secondary infection. Transfer from an outside hospital, baseline immunosuppressant use, and corticosteroid treatment were independent risk factors for secondary infection. Additional studies are needed to validate risk factors and best guide antimicrobial stewardship efforts

    The ​oestrogen receptor alpha-regulated lncRNA ​NEAT1 is a critical modulator of prostate cancer

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    The androgen receptor (AR) plays a central role in establishing an oncogenic cascade that drives prostate cancer progression. Some prostate cancers escape androgen dependence and are often associated with an aggressive phenotype. The oestrogen receptor alpha (ERα) is expressed in prostate cancers, independent of AR status. However, the role of ERα remains elusive. Using a combination of chromatin immunoprecipitation (ChIP) and RNA-sequencing data, we identified an ERα-specific non-coding transcriptome signature. Among putatively ERα-regulated intergenic long non-coding RNAs (lncRNAs), we identified nuclear enriched abundant transcript 1 (NEAT1) as the most significantly overexpressed lncRNA in prostate cancer. Analysis of two large clinical cohorts also revealed that NEAT1 expression is associated with prostate cancer progression. Prostate cancer cells expressing high levels of NEAT1 were recalcitrant to androgen or AR antagonists. Finally, we provide evidence that NEAT1 drives oncogenic growth by altering the epigenetic landscape of target gene promoters to favour transcription

    High-Energy Neutrino Follow-Up Search of Gravitational Wave Event GW150914 with ANTARES and Icecube

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    We present the high-energy-neutrino follow-up observations of the first gravitational wave transient GW150914 observed by the Advanced LIGO detectors on September 14, 2015. We search for coincident neutrino candidates within the data recorded by the IceCube and Antares neutrino detectors. A possible joint detection could be used in targeted electromagnetic follow-up observations, given the significantly better angular resolution of neutrino events compared to gravitational waves. We find no neutrino candidates in both temporal and spatial coincidence with the gravitational wave event. Within ±500 s of the gravitational wave event, the number of neutrino candidates detected by IceCube and Antares were three and zero, respectively. This is consistent with the expected atmospheric background, and none of the neutrino candidates were directionally coincident with GW150914. We use this nondetection to constrain neutrino emission from the gravitational-wave event
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