1,575 research outputs found

    How Do Real Roots Work? (Some New Views of Root Structure)

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    Extensive HST Ultraviolet Spectra and Multi-wavelength Observations of SN 2014J in M82 Indicate Reddening and Circumstellar Scattering by Typical Dust

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    SN 2014J in M82 is the closest detected Type Ia supernova (SN Ia) in at least 28 years and perhaps in 410 years. Despite its small distance of 3.3 Mpc, SN 2014J is surprisingly faint, peaking at V = 10.6 mag, and assuming a typical SN Ia luminosity, we infer an observed visual extinction of A_V = 2.0 +/- 0.1 mag. But this picture, with R_V = 1.6 +/- 0.2, is too simple to account for all observations. We combine 10 epochs (spanning a month) of HST/STIS ultraviolet through near-infrared spectroscopy with HST/WFC3, KAIT, and FanCam photometry from the optical to the infrared and 9 epochs of high-resolution TRES spectroscopy to investigate the sources of extinction and reddening for SN 2014J. We argue that the wide range of observed properties for SN 2014J is caused by a combination of dust reddening, likely originating in the interstellar medium of M82, and scattering off circumstellar material. For this model, roughly half of the extinction is caused by reddening from typical dust (E(B-V ) = 0.45 mag and R_V = 2.6) and roughly half by scattering off LMC-like dust in the circumstellar environment of SN 2014J.Comment: 17 pages (excluding references and tables), 15 figures, accepted to MNRAS. A high-resolution HST image of SN 2014J in M82 is available upon reques

    Effect of P-glycoprotein modulation with cyclosporin A on cerebrospinal fluid penetration of doxorubicin in non-human primates

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    PURPOSE: P-glycoprotein (Pgp) is a transmembrane drug efflux pump that is expressed in multidrug-resistant cancer cells and in a variety of normal tissues, including brain capillary endothelial cells which comprise the blood-brain barrier. We studied the effects of the Pgp inhibitor, cyclosporin A (CsA), on the cerebrospinal fluid (CSF) penetration of the Pgp substrate, doxorubicin, in non-human primates. METHODS: The animals received doxorubicin alone (2.0 mg/kg i.v. over 60 min) or doxorubicin (1 mg/kg i.v. over 60 min) and CsA (loading dose 4.0 mg/kg i.v. over 2 h, followed by continuous infusion of 12 mg/kg per day over 48 h). Plasma and CSF were collected over 48 h and the doxorubicin concentration was measured by reverse-phase high-pressure liquid chromatography (HPLC) with fluorescence detection (detection limit 5 nM). A two-compartment model was fitted to the plasma concentration-time data. RESULTS: Pgp was demonstrated to be present in the epithelium of the choroid plexus by immunohistochemical methods, indicating that CSF drug penetration could be used as a surrogate for blood-brain barrier penetration. Steady state whole blood CsA concentrations, which were measured with a fluorescence-polarization immunoassay (TDX) that detects both CsA and its metabolites, ranged from 551-1315 microg/l at 24 h. The clearance of doxorubicin in four animals was reduced by 34%, 38%, 45% and 49% when given with CsA. The doxorubicin concentration in the CSF was <5 nM in all animals, both after doxorubicin alone and doxorubicin with CsA. CONCLUSIONS: The Pgp inhibitor, CsA, at a concentration that alters systemic clearance of doxorubicin, does not appear to significantly increase the CSF penetration of doxorubicin

    Wellness and Multiple Sclerosis: The National MS Society Establishes a Wellness Research Working Group and Research Priorities

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    Background: People with multiple sclerosis (MS) have identified “wellness” and associated behaviors as a high priority based on “social media listening” undertaken by the National MS Society (i.e. the Society). Objective: The Society recently convened a group that consisted of researchers with experience in MS and wellness-related research, Society staff members, and an individual with MS for developing recommendations regarding a wellness research agenda. Method: The members of the group engaged in focal reviews and discussions involving the state of science within three approaches for promoting wellness in MS, namely diet, exercise, and emotional wellness. Results: That process informed a group-mediated activity for developing and prioritizing research goals for wellness in MS. This served as a background for articulating the mission and objectives of the Society’s Wellness Research Working Group. Conclusion: The primary mission of the Wellness Research Working Group is the provision of scientific evidence supporting the application of lifestyle, behavioral, and psychosocial approaches for promoting optimal health of mind, body, and spirit (i.e. wellness) in people with MS as well as managing the disease and its consequences

    AT 2017be - a new member of the class of Intermediate-Luminosity Red Transients

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    We report the results of our spectrophotometric monitoring campaign for AT~2017be in NGC~2537. Its lightcurve reveals a fast rise to an optical maximum, followed by a plateau lasting about 30 days, and finally a fast decline. Its absolute peak magnitude (MrM_{r} ≃\simeq −-12 mag\rm{mag}) is fainter than that of core-collapse supernovae, and is consistent with those of supernova impostors and other Intermediate-Luminosity Optical Transients. The quasi-bolometric lightcurve peaks at ∌\sim 2 ×\times 1040^{40} erg s−1^{-1}, and the late-time photometry allows us to constrain an ejected 56^{56}Ni mass of ∌\sim 8 ×\times 10−4^{-4}\msun. The spectra of AT~2017be show minor evolution over the observational period, a relatively blue continuum showing at early phases, which becomes redder with time. A prominent Hα\alpha emission line always dominates over other Balmer lines. Weak Fe {\sc ii} features, Ca~{\sc ii} H&\&K and the Ca {\sc ii} NIR triplet are also visible, while P-Cygni absorption troughs are found in a high resolution spectrum. In addition, the [Ca~{\sc ii}] λ\lambda7291,7324 doublet is visible in all spectra. This feature is typical of Intermediate-Luminosity Red Transients (ILRTs), similar to SN~2008S. The relatively shallow archival Spitzer data are not particularly constraining. On the other hand, a non-detection in deeper near-infrared HST images disfavours a massive Luminous Blue Variable eruption as the origin for AT~2017be. As has been suggested for other ILRTs, we propose that AT~2017be is a candidate for a weak electron-capture supernova explosion of a super-asymptotic giant branch star, still embedded in a thick dusty envelope.Comment: 21 pages, 15 figures, accepted by MNRA

    Optical and near infrared observations of SN 2014ck: an outlier among the Type Iax supernovae

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    We present a comprehensive set of optical and near-infrared photometric and spectroscopic observations for SN 2014ck, extending from pre-maximum to six months later. These data indicate that SN 2014ck is photometrically nearly identical to SN 2002cx, which is the prototype of the class of peculiar transients named SNe Iax. Similar to SN 2002cx, SN 2014ck reached a peak brightness MB=−17.37±0.15M_B=-17.37 \pm 0.15 mag, with a post-maximum decline-rate Δm15(B)=1.76±0.15\Delta m_{15} (B) = 1.76 \pm 0.15 mag. However, the spectroscopic sequence shows similarities with SN 2008ha, which was three magnitudes fainter and faster declining. In particular, SN 2014ck exhibits extremely low ejecta velocities, ∌3000\sim 3000 km s−1^{-1} at maximum, which are close to the value measured for SN 2008ha and half the value inferred for SN 2002cx. The bolometric light curve of SN 2014ck is consistent with the production of 0.10−0.03+0.04M⊙0.10^{+0.04}_{-0.03} M_{\odot} of 56^{56}Ni. The spectral identification of several iron-peak features, in particular Co II lines in the NIR, provides a clear link to SNe Ia. Also, the detection of narrow Si, S and C features in the pre-maximum spectra suggests a thermonuclear explosion mechanism. The late-phase spectra show a complex overlap of both permitted and forbidden Fe, Ca and Co lines. The appearance of strong [Ca~II] λλ\lambda\lambda7292, 7324 again mirrors the late-time spectra of SN 2008ha and SN 2002cx. The photometric resemblance to SN 2002cx and the spectral similarities to SN 2008ha highlight the peculiarity of SN 2014ck, and the complexity and heterogeneity of the SNe Iax class.Comment: MNRAS Accepted 2016 March 22. Received 2016 March
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