13 research outputs found

    An All Sky Transmission Monitor: ASTMON

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    We present here the All Sky Transmission MONitor (ASTMON), designed to perform a continuous monitoring of the surface brightness of the complete night-sky in several bands. The data acquired are used to derive, in addition, a subsequent map of the multiband atmospheric extinction at any location in the sky, and a map of the cloud coverage. The instrument has been manufactured to afford extreme weather conditions, and remain operative. Designed to be fully robotic, it is ideal to be installed outdoors, as a permanent monitoring station. The preliminary results based on two of the currently operative units (at Do\~nana National Park - Huelva- and at the Calar Alto Observatory - Almer\'ia -, in Spain), are presented here. The parameters derived using ASTMON are in good agreement with previously reported ones, what illustrates the validity of the design and the accuracy of the manufacturing. The information provided by this instrument will be presented in forthcoming articles, once we have accumulated a statistically amount of data.Comment: 12 Figures, Accepted for publishing in PAS

    The CARMENES search for exoplanets around M dwarfs High-resolution optical and near-infrared spectroscopy of 324 survey stars

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    The CARMENES radial velocity (RV) survey is observing 324 M dwarfs to search for any orbiting planets. In this paper, we present the survey sample by publishing one CARMENES spectrum for each M dwarf. These spectra cover the wavelength range 520–1710 nm at a resolution of at least R >80 000, and we measure its RV, Hα emission, and projected rotation velocity. We present an atlas of high-resolution M-dwarf spectra and compare the spectra to atmospheric models. To quantify the RV precision that can be achieved in low-mass stars over the CARMENES wavelength range, we analyze our empirical information on the RV precision from more than 6500 observations. We compare our high-resolution M-dwarf spectra to atmospheric models where we determine the spectroscopic RV information content, Q, and signal-to-noise ratio. We find that for all M-type dwarfs, the highest RV precision can be reached in the wavelength range 700–900 nm. Observations at longer wavelengths are equally precise only at the very latest spectral types (M8 and M9). We demonstrate that in this spectroscopic range, the large amount of absorption features compensates for the intrinsic faintness of an M7 star. To reach an RV precision of 1 m s−1 in very low mass M dwarfs at longer wavelengths likely requires the use of a 10 m class telescope. For spectral types M6 and earlier, the combination of a red visual and a near-infrared spectrograph is ideal to search for low-mass planets and to distinguish between planets and stellar variability. At a 4 m class telescope, an instrument like CARMENES has the potential to push the RV precision well below the typical jitter level of 3–4 m s−1

    The CARMENES search for exoplanets around M dwarfs. First visual-channel radial-velocity measurements and orbital parameter updates of seven M-dwarf planetary systems

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    Stars and planetary system

    CARMENES: high-resolution spectra and precise radial velocities in the red and infrared

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    SPIE Astronomical Telescopes + Instrumentation (2018, Austin, Texas, United States

    Peripheral modulation of antidepressant targets MAO-B and GABAAR by harmol induces mitohormesis and delays aging in preclinical models

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    Reversible and sub-lethal stresses to the mitochondria elicit a program of compensatory responses that ultimately improve mitochondrial function, a conserved anti-aging mechanism termed mitohormesis. Here, we show that harmol, a member of the beta-carbolines family with anti-depressant properties, improves mitochondrial function and metabolic parameters, and extends healthspan. Treatment with harmol induces a transient mitochondrial depolarization, a strong mitophagy response, and the AMPK compensatory pathway both in cultured C2C12 myotubes and in male mouse liver, brown adipose tissue and muscle, even though harmol crosses poorly the blood–brain barrier. Mechanistically, simultaneous modulation of the targets of harmol monoamine-oxidase B and GABA-A receptor reproduces harmol-induced mitochondrial improvements. Diet-induced pre-diabetic male mice improve their glucose tolerance, liver steatosis and insulin sensitivity after treatment with harmol. Harmol or a combination of monoamine oxidase B and GABA-A receptor modulators extend the lifespan of hermaphrodite Caenorhabditis elegans or female Drosophila melanogaster. Finally, two-year-old male and female mice treated with harmol exhibit delayed frailty onset with improved glycemia, exercise performance and strength. Our results reveal that peripheral targeting of monoamine oxidase B and GABA-A receptor, common antidepressant targets, extends healthspan through mitohormesis

    Enhanced Solar-Photocatalytic Degradation of Combined Chlorophenols Using Ferric Ions and Hydrogen Peroxide

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    The influences of ferric ions (Fe3+) and hydrogen peroxide (H2O2) on the degradation of combined chlorophenols during solar/TiO2 process were investigated. 4-Chlorophenol (4-CP) and 2,4-dichlorophenol (2,4-DCP) were used as a chlorophenols combined mixture. Fe3+ ions have shown considerable effect on the solar-photocatalytic degradation rate of the mixture and its intermediates. Different amounts of Fe3+ ions were used, and the optimum value was 10 mg/L. At these conditions, three major intermediates were detected including hydroquinone (HQ), phenol (Ph), and 4-chlorocatechol (4-cCat). However, the concentrations of these aromatic intermediates were less than that of using TiO2 alone as well as the degradation time was reduced to 150 min. H2O2 was also effectively used as a degradation enhancer at various concentrations together with Fe3+ ions in order to improve the solar-photocatalytic degradation rate and the optimum value was 3.41 mM. The degradation efficiency of the combined mixture increased sharply in the presence of H2O2. Additionally, an extremely high degradation rate of the main pollutants and their intermediates was achieved when using Fe3+ ions and H2O2 together with TiO2. Furthermore, only two intermediates HQ and Ph were observed in this case. The complete degradation of the main chlorophenolic compounds and their intermediates was achieved within 130 min of solar irradiation
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