8 research outputs found

    Planet Hunters X: Searching for Nearby Neighbors of 75 Planet and Eclipsing Binary Candidates from the K2 Kepler Extended Mission

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    We present high-resolution observations of a sample of 75 K2 targets from Campaigns 1-3 using speckle interferometry on the Southern Astrophysical Research (SOAR) telescope and adaptive optics (AO) imaging at the Keck II telescope. The median SOAR II-band and Keck KsK_s-band detection limits at 1" were ΔmI=4.4\Delta m_{I}=4.4~mag and ΔmKs=6.1\Delta m_{K_s}=6.1~mag, respectively. This sample includes 37 stars likely to host planets, 32 targets likely to be eclipsing binaries (EBs), and 6 other targets previously labeled as likely planetary false positives. We find nine likely physically bound companion stars within 3" of three candidate transiting exoplanet host stars and six likely EBs. Six of the nine detected companions are new discoveries; one of the six, EPIC 206061524, is associated with a planet candidate. Among the EB candidates, companions were only found near the shortest period ones (P<3P<3 days), which is in line with previous results showing high multiplicity near short-period binary stars. This high-resolution data, including both the detected companions and the limits on potential unseen companions, will be useful in future planet vetting and stellar multiplicity rate studies for planets and binaries.Comment: Accepted in A

    Planet Hunters X: Searching for nearby neighbors of 75 planet and eclipsing binary candidates from the K2 Kepler extended mission

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    We present high resolution observations of a sample of 75 K2 targets from Campaigns 1-3 using speckle interferometry on the Southern Astrophysical Research (SOAR) telescope and adaptive optics (AO) imaging at the Keck II telescope. The median SOAR II-band and Keck KsK_s-band detection limits at 1'' were ΔmI=4.4\Delta m_{I}=4.4 mag and ΔmKs=6.1\Delta m_{K_s}=6.1 mag, respectively. This sample includes 37 stars likely to host planets, 32 targets likely to be EBs, and 6 other targets previously labeled as likely planetary false positives. We find nine likely physically bound companion stars within 3'' of three candidate transiting exoplanet host stars and six likely eclipsing binaries (EB). Six of the nine detected companions are new discoveries, one of them associated with a planet candidate (EPIC 206061524). Among the EB candidates, companions were only found near the shortest period ones (P<3 days), which is in line with previous results showing high multiplicity near short-period binary stars. This high resolution data, including both the detected companions and the limits on potential unseen companions, will be useful in future planet vetting and stellar multiplicity rate studies for planets and binaries

    Cyano-bridged homodinuclear copper(II) complexes

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    The synthesis and structural analysis (single crystal X-ray data) of two mononuclear ([Cu(L)(CN)]BF and [Cu(L)(CN)] (BF)) and three related, cyanide-bridged homodinuclear complexes ([{Cu(L)}(CN)](BF)•1.35 HO, [{Cu(L)}(CN)](BF) and [{Ni(L)}(CN)](BF) ) with a tetradentate (L) and two isomeric pentadentate bispidine ligands (L, L; bispidines are 3,7-diazabicyclo[3.3.1]nonane derivatives) are reported, together with experimental magnetic, electron paramagnetic resonance (EPR), and electronic spectroscopic data and a ligand-field-theory-based analysis. The temperature dependence of the magnetic susceptibilities and EPR transitions of the dicopper(II) complexes, together with the simulation of the EPR spectra of the mono- and dinuclear complexes leads to an anisotropic set of g- and A-values, zero-field splitting (ZFS) and magnetic exchange parameters (Cu1: g = 2.055, g = 2.096, g = 2.260, A = 8, A = 8, A = 195 × 10 cm, Cu2: g and A as for Cu but rotated by the Euler angles α = -6°, β = 100°, D = -0.07 cm, E /D = 0.205 for [{Cu(L)} (CN)](BF)•1.35 HO; Cu1,2: g = 2.025, g = 2.096, g = 2.240, A = 8, A = 8, A = 190 × 10 cm, D = -0.159 cm, E /D = 0.080 for [{Cu(L)} (CN)](BF)). Thorough ligand-field-theory- based analyses, involving all micro states and all relevant interactions (Jahn-Teller and spin-orbit coupling) and DFT calculations of the magnetic exchange leads to good agreement between the experimental observations and theoretical predictions. The direction of the symmetric magnetic anisotropy tensor D in [{Cu(L)}(CN)](BF ) is close to the Cu•••Cu vector (22°), that is, nearly perpendicular to the Jahn-Teller axis of each of the two Cu centers, and this reflects the crystallographically observed geometry. Antisymmetric exchange in [{Cu(L)}(CN)] (BF)•1.35 HO causes a mixing between the singlet ground state and the triplet excited state, and this also reflects the observed geometry with a rotation of the two Cu sites around the Cu•••Cu axis

    Guidelines for the use and interpretation of assays for monitoring autophagy (4th edition)

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    In 2008, we published the first set of guidelines for standardizing research in autophagy. Since then, this topic has received increasing attention, and many scientists have entered the field. Our knowledge base and relevant new technologies have also been expanding. Thus, it is important to formulate on a regular basis updated guidelines for monitoring autophagy in different organisms. Despite numerous reviews, there continues to be confusion regarding acceptable methods to evaluate autophagy, especially in multicellular eukaryotes. Here, we present a set of guidelines for investigators to select and interpret methods to examine autophagy and related processes, and for reviewers to provide realistic and reasonable critiques of reports that are focused on these processes. These guidelines are not meant to be a dogmatic set of rules, because the appropriateness of any assay largely depends on the question being asked and the system being used. Moreover, no individual assay is perfect for every situation, calling for the use of multiple techniques to properly monitor autophagy in each experimental setting. Finally, several core components of the autophagy machinery have been implicated in distinct autophagic processes (canonical and noncanonical autophagy), implying that genetic approaches to block autophagy should rely on targeting two or more autophagy-related genes that ideally participate in distinct steps of the pathway. Along similar lines, because multiple proteins involved in autophagy also regulate other cellular pathways including apoptosis, not all of them can be used as a specific marker for bona fide autophagic responses. Here, we critically discuss current methods of assessing autophagy and the information they can, or cannot, provide. Our ultimate goal is to encourage intellectual and technical innovation in the field
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