Context. Interferometry can provide spatially resolved observations of massive star binary systems and their colliding winds, which thus far have been studied mostly with spatially unresolved ...observations. Aims. We present the first AMBER/VLTI observations, taken at orbital phase 0.32, of the Wolf-Rayet and O (WR+O) star binary system γ2 Velorum and use the interferometric observables to constrain its properties. Methods. The AMBER/VLTI instrument was used with the telescopes UT2, UT3, and UT4 on baselines ranging from 46 m to 85 m. It delivered spectrally dispersed visibilities, as well as differential and closure phases, with a resolution $R=1500$ in the spectral band 1.95-2.17 μm. We interpret these data in the context of a binary system with unresolved components, neglecting in a first approximation the wind-wind collision zone flux contribution. Results. Using WR- and O-star synthetic spectra, we show that the AMBER/VLTI observables result primarily from the contribution of the individual components of the WR+O binary system. We discuss several interpretations of the residuals, and speculate on the detection of an additional continuum component, originating from the free-free emission associated with the wind-wind collision zone (WWCZ), and contributing at most to the observed K-band flux at the 5% level. Based on the accurate spectroscopic orbit and the Hipparcos distance, the expected absolute separation and position angle at the time of observations were $5.1\pm0.9$ mas and $66\pm15$°, respectively. However, using theoretical estimates for the spatial extent of both continuum and line emission from each component, we infer a separation of 3.62$^{+0.11}_{-0.30}$ mas and a position angle of 73$^{+9}_{-11}$°, compatible with the expected one. Our analysis thus implies that the binary system lies at a distance of 368$^{+38}_{-13}$ pc, in agreement with recent spectrophotometric estimates, but significantly larger than the Hipparcos value of 258$^{+41}_{-31}$ pc.
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FMFMET, NUK, UL, UM, UPUK
SPHERE+ is a proposed upgrade of the SPHERE instrument at the VLT, which is intended to boost the current performances of detection and characterization for exoplanets and disks. SPHERE+ will also ...serve as a demonstrator for the future planet finder (PCS) of the European ELT. The main science drivers for SPHERE+ are 1/ to access the bulk of the young giant planet population down to the snow line (\(3-10\) au), to bridge the gap with complementary techniques (radial velocity, astrometry); 2/ to observe fainter and redder targets in the youngest (\(1-10\)\,Myr) associations compared to those observed with SPHERE to directly study the formation of giant planets in their birth environment; 3/ to improve the level of characterization of exoplanetary atmospheres by increasing the spectral resolution in order to break degeneracies in giant planet atmosphere models. Achieving these objectives requires to increase the bandwidth of the xAO system (from \(\sim\)1 to 3\,kHz) as well as the sensitivity in the infrared (2 to 3\,mag). These features will be brought by a second stage AO system optimized in the infrared with a pyramid wavefront sensor. As a new science instrument, a medium resolution integral field spectrograph will provide a spectral resolution from 1000 to 5000 in the J and H bands. This paper gives an overview of the science drivers, requirements and key instrumental trade-off that were done for SPHERE+ to reach the final selected baseline concept.
Locteron, a newly developed controlled-release formulation of Lemna-derived free (unpegylated) recombinant interferon-alpha2b (IFN-alpha2b, Biolex Therapeutics, Pittsboro, NC) in poly(ether-ester) ...microspheres (PolyActive, OctoPlus N.V., Leiden, the Netherlands), was evaluated in 27 volunteers injected with either 20, 80, or 320 microg Locteron (equivalent to 6.25, 25, or 100 x 10(6) IU, respectively), 80 microg pegylated IFN-alpha2b (PEG-IFN-alpha2b), microspheres not containing IFN-alpha2b, or placebo. Serum free or PEG-IFN-alpha2b and two biomarkers of IFN activity, neopterin and 2',5'-oligoadenylate synthetase (2',5'-OAS), were measured. After injection of 320 microg Locteron, serum IFN-alpha2b remained elevated through 14 days. The elimination half-life of Locteron was more than 2-fold that of PEG-IFN-alpha2b. The effects of 80 microg Locteron and 80 microg PEG-IFN-alpha2b on both neopterin and 2',5'-OAS were in a comparable range. Serum persistence of both these biomarkers was similar at 14 days after 320 microg Locteron compared with 7 days after 80 microg PEG-IFN-alpha2b. Mild, moderate, or severe influenza-like symptoms developed in all 6 subjects receiving 80 microg PEG-IFN-alpha2b. No such symptoms occurred after 20 or 80 microg Locteron doses. Among the 4 recipients of 320 microg Locteron, 1 experienced mild and 2 experienced moderate influenza-like symptoms. Locteron merits further clinical investigation as a hepatitis C therapy suitable for dosing once per 2 weeks.
Lately, there has been a particular interest in increasing the bandwidth of the ionospheric channel in the high frequency (HF) range. Tests on the use of bandwidths of up to 24kHz have shown that ...under certain conditions a substantial increase in the data transfer rate in the HF range could be achieved. But the bandwidth increase is limited mainly due to the noise level. This paper approaches a preliminary experimental analysis of the noise power levels in variable bandwidth ionospheric channels under Near Vertical Incidence Skywave (NVIS) operating conditions in the 3-9 MHz band. The results show that the mean noise power increases by an average of 3.5 dB at doubling the bandwidth of the ionospheric channel, while the dispersion of noise is maintained (at maximum 9.5 dB) regardless of the bandwidth of the ionospheric channel.
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