772 research outputs found

    Photometric and spectroscopic analysis of the Type II SN 2020jfo with a short plateau

    Full text link
    We present high-cadence photometric and spectroscopic observations of SN~2020jfo in ultraviolet and optical/near-infrared bands starting from 3\sim 3 to 434\sim 434 days after the explosion, including the earliest data with the 10.4\,m GTC. SN~2020jfo is a hydrogen-rich Type II SN with a relatively short plateau duration (67.0±0.667.0 \pm 0.6 days). When compared to other Type II supernovae (SNe) of similar or shorter plateau lengths, SN~2020jfo exhibits a fainter peak absolute VV-band magnitude (MV=16.90±0.34M_V = -16.90 \pm 0.34 mag). SN~2020jfo shows significant Hα\alpha absorption in the plateau phase similar to that of typical SNe~II. The emission line of stable [Ni~II] λ\lambda7378, mostly seen in low-luminosity SNe~II, is very prominent in the nebular-phase spectra of SN~2020jfo. Using the relative strengths of [Ni~II] λ\lambda7378 and [Fe~II] λ\lambda7155, we derive the Ni/Fe production (abundance) ratio of 0.08--0.10, which is 1.5\sim 1.5 times the solar value. The progenitor mass of SN~2020jfo from nebular-phase spectral modelling and semi-analytical modelling falls in the range of 12--15\,MM_\odot. Furthermore, semi-analytical modelling suggests a massive H envelope in the progenitor of SN~2020jfo, which is unlikely for SNe~II having short plateaus.Comment: 20 pages (plus 5 pages appendix), 19 figures, Accepted for publication in MNRA

    Thermodynamic study of interactions between ZnO and ZnO binding peptides using isothermal titration calorimetry

    Get PDF
    Whilst material specific peptide binding sequences have been identified using a combination of combinato-rial methods and computational modelling tools, a deep molecular level understanding of the fundamental principles through which these interactions occur and in some instances modify the morphology of inorganic materials is far from being fully realized. Understanding the thermodynamic changes that occur during peptide-inorganic interactions and correlating these to structural modifications of the inorganic materials could be the key to achieving and mastering con-trol over material formation processes. This study is a detailed investigation applying isothermal titration calorimetry (ITC) to directly probe thermodynamic changes that occur during interaction of ZnO binding peptides (ZnO-BPs) and ZnO. The ZnO-BPs used are reported sequences G-12 (GLHVMHKVAPPR), GT-16 (GLHVMHKVAPPR-GGGC) and alanine mutants of G-12 (G-12A6, G-12A11 and G-12A12) whose interaction with ZnO during solution synthesis studies have been extensively investigated. The interactions of the ZnO-BPs with ZnO yielded biphasic isotherms comprising both an endo-thermic and an exothermic event. Qualitative differences were observed in the isothermal profiles of the different pep-tides and ZnO particles studied. Measured ΔG values were between -6 and -8.5 kcal/mol and high adsorption affinity val-ues indicated the occurrence of favourable ZnO-BP-ZnO interactions. ITC has great potential in its use to understand peptide-inorganic interactions and with continued development, the knowledge gained may be instrumental for simplifi-cation of selection processes of organic molecules for the advancement of material synthesis and design

    Primary Black Hole Spin in OJ 287 as Determined by the General Relativity Centenary Flare

    Get PDF
    OJ 287 is a quasi-periodic quasar with roughly 12 year optical cycles. It displays prominent outbursts that are predictable in a binary black hole model. The model predicted a major optical outburst in 2015 December. We found that the outburst did occur within the expected time range, peaking on 2015 December 5 at magnitude 12.9 in the optical R -band. Based on Swift /XRT satellite measurements and optical polarization data, we find that it included a major thermal component. Its timing provides an accurate estimate for the spin of the primary black hole, ##IMG## [http://ej.iop.org/images/2041-8205/819/2/L37/apjl523055ieqn1.gif] i=0.313pm0.01i =0.313pm 0.01 . The present outburst also confirms the established general relativistic properties of the system such as the loss of orbital energy to gravitational radiation at the 2% accuracy level, and it opens up the possibility of testing the black hole no-hair theorem with 10% accuracy during the present decade.Peer reviewe

    A Search for QPOs in the Blazar OJ287: Preliminary Results from the 2015/2016 Observing Campaign

    Get PDF
    We analyse the light curve in the R band of the blazar OJ287, gathered during the 2015/2016 observing season. We did a search for quasi-periodic oscillations (QPOs) using several methods over a wide range of timescales. No statistically significant periods were found in the high-frequency domain both in the ground-based data and in Kepler observations. In the longer-period domain, the Lomb–Scargle periodogram revealed several peaks above the 99% significance level. The longest one—about 95 days—corresponds to the innermost stable circular orbit (ISCO) period of the more massive black hole. The 43-day period could be an alias, or it can be attributed to accretion in the form of a two-armed spiral wave.Peer reviewe

    Cross-Section Measurement of Virtual Photoproduction of Iso-Triplet Three-Body Hypernucleus, ⋀nn

    Get PDF
    Missing-mass spectroscopy with the 3H(e, e′K+) reaction was carried out at Jefferson Lab’s (JLab) Hall A in Oct–Nov, 2018. The differential cross section for the 3H(γ∗, K+)Λnn was deduced at ω = Ee − Ee′ = 2.102 GeV and at the forward K+-scattering angle (0° ≤ θγ∗K ≤ 5°) in the laboratory frame. Given typical predicted energies and decay widths, which are (BΛ, Γ) = (−0.25, 0.8) and (−0.55, 4.7) MeV, the cross sections were found to be 11.2 ± 4.8(stat.)+4.1−2.1(sys.) and 18.1 ± 6.8(stat.)+4.2−2.9(sys.) nb/sr, respectively. The obtained result would impose a constraint for interaction models particularly between Λ and neutron by comparing to theoretical calculations

    The genome of cultivated peanut provides insight into legume karyotypes, polyploid evolution and crop domestication

    Get PDF
    High oil and protein content make tetraploid peanut a leading oil and food legume. Here we report a high-quality peanut genome sequence, comprising 2.54 Gb with 20 pseudomolecules and 83,709 protein-coding gene models. We characterize gene functional groups implicated in seed size evolution, seed oil content, disease resistance and symbiotic nitrogen fixation. The peanut B subgenome has more genes and general expression dominance, temporally associated with long-terminal-repeat expansion in the A subgenome that also raises questions about the A-genome progenitor. The polyploid genome provided insights into the evolution of Arachis hypogaea and other legume chromosomes. Resequencing of 52 accessions suggests that independent domestications formed peanut ecotypes. Whereas 0.42–0.47 million years ago (Ma) polyploidy constrained genetic variation, the peanut genome sequence aids mapping and candidate-gene discovery for traits such as seed size and color, foliar disease resistance and others, also providing a cornerstone for functional genomics and peanut improvement

    Search for low-mass dark matter via bremsstrahlung radiation and the Migdal effect in SuperCDMS

    Get PDF
    We present a new analysis of previously published SuperCDMS data using a profile likelihood framework to search for sub-GeV dark matter (DM) particles through two inelastic scattering channels: bremsstrahlung radiation and the Migdal effect. By considering these possible inelastic scattering channels, experimental sensitivity can be extended to DM masses that are undetectable through the DM-nucleon elastic scattering channel, given the energy threshold of current experiments. We exclude DM masses down to 220  MeV/c2 at 2.7×10−30  cm2 via the bremsstrahlung channel. The Migdal channel search provides overall considerably more stringent limits and excludes DM masses down to 30  MeV/c2 at 5.0×10−30  cm2

    Authenticating the Presence of a Relativistic Massive Black Hole Binary in OJ 287 Using Its General Relativity Centenary Flare : Improved Orbital Parameters

    Get PDF
    Results from regular monitoring of relativistic compact binaries like PSR 1913+16 are consistent with the dominant (quadrupole) order emission of gravitational waves (GWs). We show that observations associated with the binary black hole (BBH) central engine of blazar OJ 287 demand the inclusion of gravitational radiation reaction effects beyond the quadrupolar order. It turns out that even the effects of certain hereditary contributions to GW emission are required to predict impact flare timings of OJ 287. We develop an approach that incorporates this effect into the BBH model for OJ 287. This allows us to demonstrate an excellent agreement between the observed impact flare timings and those predicted from ten orbital cycles of the BBH central engine model. The deduced rate of orbital period decay is nine orders of magnitude higher than the observed rate in PSR 1913+16, demonstrating again the relativistic nature of OJ 287's central engine. Finally, we argue that precise timing of the predicted 2019 impact flare should allow a test of the celebrated black hole "no-hair theorem" at the 10% level.Peer reviewe

    Removal of Hepatitis C Virus-Infected Cells by a Zymogenized Bacterial Toxin

    Get PDF
    Hepatitis C virus (HCV) infection is a major cause of chronic liver disease and has become a global health threat. No HCV vaccine is currently available and treatment with antiviral therapy is associated with adverse side effects. Moreover, there is no preventive therapy for recurrent hepatitis C post liver transplantation. The NS3 serine protease is necessary for HCV replication and represents a prime target for developing anti HCV therapies. Recently we described a therapeutic approach for eradication of HCV infected cells that is based on protein delivery of two NS3 protease-activatable recombinant toxins we named “zymoxins”. These toxins were inactivated by fusion to rationally designed inhibitory peptides via NS3-cleavable linkers. Once delivered to cells where NS3 protease is present, the inhibitory peptide is removed resulting in re-activation of cytotoxic activity. The zymoxins we described suffered from two limitations: they required high levels of protease for activation and had basal activities in the un-activated form that resulted in a narrow potential therapeutic window. Here, we present a solution that overcame the major limitations of the “first generation zymoxins” by converting MazF ribonuclease, the toxic component of the E. coli chromosomal MazEF toxin-antitoxin system, into an NS3-activated zymoxin that is introduced to cells by means of gene delivery. We constructed an expression cassette that encodes for a single polypeptide that incorporates both the toxin and a fragment of its potent natural antidote, MazE, linked via an NS3-cleavable linker. While covalently paired to its inhibitor, the ribonuclease is well tolerated when expressed in naïve, healthy cells. In contrast, activating proteolysis that is induced by even low levels of NS3, results in an eradication of NS3 expressing model cells and HCV infected cells. Zymoxins may thus become a valuable tool in eradicating cells infected by intracellular pathogens that express intracellular proteases
    corecore