614 research outputs found

    Absorptive Capacity and Frontier Technology: Evidence from OECD Manufacturing Industries

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    This paper investigates whether differences in absorptive capacity help to explain cross-country differences in the level of productivity. We utilise stochastic frontier analysis to investigate two potential sources of this inefficiency: differences in human capital and R&D for nine industries in twelve OECD countries over the period 1973-92. We find that inefficiency in production does indeed exist and it depends upon the level of human capital of the countryÕs workforce.Evidence that the amount of R&D an industry undertakes is also important is less robust. Classification- JEL: O3, O4absorptive capacity, human capital, R&D, SFA

    Population Genomics: Whole-Genome Analysis of Polymorphism and Divergence in Drosophila simulans

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    The population genetic perspective is that the processes shaping genomic variation can be revealed only through simultaneous investigation of sequence polymorphism and divergence within and between closely related species. Here we present a population genetic analysis of Drosophila simulans based on whole-genome shotgun sequencing of multiple inbred lines and comparison of the resulting data to genome assemblies of the closely related species, D. melanogaster and D. yakuba. We discovered previously unknown, large-scale fluctuations of polymorphism and divergence along chromosome arms, and significantly less polymorphism and faster divergence on the X chromosome. We generated a comprehensive list of functional elements in the D. simulans genome influenced by adaptive evolution. Finally, we characterized genomic patterns of base composition for coding and noncoding sequence. These results suggest several new hypotheses regarding the genetic and biological mechanisms controlling polymorphism and divergence across the Drosophila genome, and provide a rich resource for the investigation of adaptive evolution and functional variation in D. simulans

    KELT-8b: A highly inflated transiting hot Jupiter and a new technique for extracting high-precision radial velocities from noisy spectra

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    We announce the discovery of a highly inflated transiting hot Jupiter discovered by the KELT-North survey. A global analysis including constraints from isochrones indicates that the V = 10.8 host star (HD 343246) is a mildly evolved, G dwarf with Teff=575455+54T_{\rm eff} = 5754_{-55}^{+54} K, logg=4.0780.054+0.049\log{g} = 4.078_{-0.054}^{+0.049}, [Fe/H]=0.272±0.038[Fe/H] = 0.272\pm0.038, an inferred mass M=1.2110.066+0.078M_{*}=1.211_{-0.066}^{+0.078} M_{\odot}, and radius R=1.670.12+0.14R_{*}=1.67_{-0.12}^{+0.14} R_{\odot}. The planetary companion has mass MP=0.8670.061+0.065M_P = 0.867_{-0.061}^{+0.065} MJM_{J}, radius RP=1.860.16+0.18R_P = 1.86_{-0.16}^{+0.18} RJR_{J}, surface gravity loggP=2.7930.075+0.072\log{g_{P}} = 2.793_{-0.075}^{+0.072}, and density ρP=0.1670.038+0.047\rho_P = 0.167_{-0.038}^{+0.047} g cm3^{-3}. The planet is on a roughly circular orbit with semimajor axis a=0.045710.00084+0.00096a = 0.04571_{-0.00084}^{+0.00096} AU and eccentricity e=0.0350.025+0.050e = 0.035_{-0.025}^{+0.050}. The best-fit linear ephemeris is T0=2456883.4803±0.0007T_0 = 2456883.4803 \pm 0.0007 BJDTDB_{\rm TDB} and P=3.24406±0.00016P = 3.24406 \pm 0.00016 days. This planet is one of the most inflated of all known transiting exoplanets, making it one of the few members of a class of extremely low density, highly-irradiated gas giants. The low stellar logg\log{g} and large implied radius are supported by stellar density constraints from follow-up light curves, plus an evolutionary and space motion analysis. We also develop a new technique to extract high precision radial velocities from noisy spectra that reduces the observing time needed to confirm transiting planet candidates. This planet boasts deep transits of a bright star, a large inferred atmospheric scale height, and a high equilibrium temperature of Teq=167555+61T_{eq}=1675^{+61}_{-55} K, assuming zero albedo and perfect heat redistribution, making it one of the best targets for future atmospheric characterization studies.Comment: Submitted to ApJ, feedback is welcom

    KELT-11b: A Highly Inflated Sub-Saturn Exoplanet Transiting the V=8 Subgiant HD 93396

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    We report the discovery of a transiting exoplanet, KELT-11b, orbiting the bright (V=8.0V=8.0) subgiant HD 93396. A global analysis of the system shows that the host star is an evolved subgiant star with Teff=5370±51T_{\rm eff} = 5370\pm51 K, M=1.4380.052+0.061MM_{*} = 1.438_{-0.052}^{+0.061} M_{\odot}, R=2.720.17+0.21RR_{*} = 2.72_{-0.17}^{+0.21} R_{\odot}, log g=3.7270.046+0.040g_*= 3.727_{-0.046}^{+0.040}, and [Fe/H]=0.180±0.075 = 0.180\pm0.075. The planet is a low-mass gas giant in a P=4.736529±0.00006P = 4.736529\pm0.00006 day orbit, with MP=0.195±0.018MJM_{P} = 0.195\pm0.018 M_J, RP=1.370.12+0.15RJR_{P}= 1.37_{-0.12}^{+0.15} R_J, ρP=0.0930.024+0.028\rho_{P} = 0.093_{-0.024}^{+0.028} g cm3^{-3}, surface gravity log gP=2.4070.086+0.080{g_{P}} = 2.407_{-0.086}^{+0.080}, and equilibrium temperature Teq=171246+51T_{eq} = 1712_{-46}^{+51} K. KELT-11 is the brightest known transiting exoplanet host in the southern hemisphere by more than a magnitude, and is the 6th brightest transit host to date. The planet is one of the most inflated planets known, with an exceptionally large atmospheric scale height (2763 km), and an associated size of the expected atmospheric transmission signal of 5.6%. These attributes make the KELT-11 system a valuable target for follow-up and atmospheric characterization, and it promises to become one of the benchmark systems for the study of inflated exoplanets.Comment: 15 pages, Submitted to AAS Journal

    Two Planets Straddling the Habitable Zone of The Nearby K dwarf Gl 414A

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    We present the discovery of two planets orbiting the nearby (D = 11.9 pc) K7 dwarf Gl 414A. Gl 414A b is a sub-Neptune mass planet with M_b sin i_b = 9.28^(+3.19)_(−2.54) M_⊕ and a semi-major axis of 0.24 ± 0.01 au. Gl 414A c is a sub-Saturn mass planet with M_c sin i_c = 59.48^(+9.98)_(−9.69) M_⊕ and a semi-major axis of 1.43 ± 0.06 au. We jointly analyzed radial velocity data from Keck/HIRES and the Automated Planet Finder at Lick Observatory, as well as photometric data from KELT, to detect the two planets as well as two additional signals related to the rotationally-modulated activity and the long term magnetic activity cycle of the star. The outer planet in this system is a potential candidate for future direct imaging missions

    KElt-18b: Puffy planet, hot host, probably perturbed

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    We report the discovery of KELT-18b, a transiting hot Jupiter in a 2.87-day orbit around the bright (V = 10.1), hot, F4V star BD+60 1538 (TYC 3865-1173-1). We present follow-up photometry, spectroscopy, and adaptive optics imaging that allow a detailed characterization of the system. Our preferred model fits yield a host stellar temperature of K and a mass of, situating it as one of only a handful of known transiting planets with hosts that are as hot, massive, and bright. The planet has a mass of, a radius of, and a density of, making it one of the most inflated planets known around a hot star. We argue that KELT-18b\u27s high temperature and low surface gravity, which yield an estimated ∼600 km atmospheric scale height, combined with its hot, bright host, make it an excellent candidate for observations aimed at atmospheric characterization. We also present evidence for a bound stellar companion at a projected separation of ∼1100 au, and speculate that it may have contributed to the strong misalignment we suspect between KELT-18\u27s spin axis and its planet\u27s orbital axis. The inferior conjunction time is 2457542.524998 ± 0.000416 (BJDTDB) and the orbital period is 2.8717510 ± 0.0000029 days. We encourage Rossiter-McLaughlin measurements in the near future to confirm the suspected spin-orbit misalignment of this system

    KELT-12b: A P ∼ 5 day, Highly Inflated Hot Jupiter Transiting a Mildly Evolved Hot Star

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    We announce the discovery of KELT-12b, a highly inflated Jupiter-mass planet transiting the mildly evolved, V = 10.64 host star TYC 2619-1057-1. We followed up the initial transit signal in the KELT-North survey data with precise ground-based photometry, high-resolution spectroscopy, precise radial velocity measurements, and high-resolution adaptive optics imaging. Our preferred best-fit model indicates that the host star has = 6279 ±51 K, = 3.89 ±0.05, [Fe/H] = 0.19+0.08-0.09, = M∗ = 1.59+0.070.09M, and R ∗= 2.37 ±0.17 . The planetary companion has Mp= 0.95 ±0.14 MJ, RP = 1.78+0.17-0.16 RJ, log gP = 2.87+0.9-0.09 and density pp 0.210.070.05= g cm-3, making it one of the most inflated giant planets known. Furthermore, for future follow-up, we report a high-precision time of inferior conjunction in BJDTDB of 2,457,083.660459 ±0.000894 and period of P = 5.0316216 ± 0.000032days. Despite the relatively large separation of ∼0.07 au implied by its ∼5.03-day orbital period, KELT-12b receives significant flux of 2.38+0.32-0.29 × 109 erg s-1 cm-2 from its host. We compare the radii and insolations of transiting gas giant planets around hot (Teff 6250 K) and cool stars, noting that the observed paucity of known transiting giants around hot stars with low insolation is likely due to selection effects. We underscore the significance of long-term ground-based monitoring of hot stars and space-based targeting of hot stars with the Transiting Exoplanet Survey Satellite to search for inflated gas giants in longer-period orbits

    Effects of antiplatelet therapy on stroke risk by brain imaging features of intracerebral haemorrhage and cerebral small vessel diseases: subgroup analyses of the RESTART randomised, open-label trial

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    Background Findings from the RESTART trial suggest that starting antiplatelet therapy might reduce the risk of recurrent symptomatic intracerebral haemorrhage compared with avoiding antiplatelet therapy. Brain imaging features of intracerebral haemorrhage and cerebral small vessel diseases (such as cerebral microbleeds) are associated with greater risks of recurrent intracerebral haemorrhage. We did subgroup analyses of the RESTART trial to explore whether these brain imaging features modify the effects of antiplatelet therapy

    The mysterious dimmings of the T Tauri star V1334 Tau

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    We present the discovery of two extended ˜0.12 mag dimming events of the weak-lined T Tauri star V1334. The start of the first event was missed but came to an end in late 2003, and the second began in 2009 February, and continues as of 2016 November. Since the egress of the current event has not yet been observed, it suggests a period of >13 years if this event is periodic. Spectroscopic observations suggest the presence of a small inner disk, although the spectral energy distribution shows no infrared excess. We explore the possibility that the dimming events are caused by an orbiting body (e.g., a disk warp or dust trap), enhanced disk winds, hydrodynamical fluctuations of the inner disk, or a significant increase in the magnetic field flux at the surface of the star. We also find a ˜0.32 day periodic photometric signal that persists throughout the 2009 dimming which appears to not be due to ellipsoidal variations from a close stellar companion. High-precision photometric observations of V1334 Tau during K2 campaign 13, combined with simultaneous photometric and spectroscopic observations from the ground, will provide crucial information about the photometric variability and its origin

    Another Shipment of Six Short-Period Giant Planets from TESS

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    We present the discovery and characterization of six short-period, transiting giant planets from NASA's Transiting Exoplanet Survey Satellite (TESS) -- TOI-1811 (TIC 376524552), TOI-2025 (TIC 394050135), TOI-2145 (TIC 88992642), TOI-2152 (TIC 395393265), TOI-2154 (TIC 428787891), & TOI-2497 (TIC 97568467). All six planets orbit bright host stars (8.9 <G< 11.8, 7.7 <K< 10.1). Using a combination of time-series photometric and spectroscopic follow-up observations from the TESS Follow-up Observing Program (TFOP) Working Group, we have determined that the planets are Jovian-sized (RP_{P} = 1.00-1.45 RJ_{J}), have masses ranging from 0.92 to 5.35 MJ_{J}, and orbit F, G, and K stars (4753 << Teff_{eff} << 7360 K). We detect a significant orbital eccentricity for the three longest-period systems in our sample: TOI-2025 b (P = 8.872 days, ee = 0.220±0.0530.220\pm0.053), TOI-2145 b (P = 10.261 days, ee = 0.1820.049+0.0390.182^{+0.039}_{-0.049}), and TOI-2497 b (P = 10.656 days, ee = 0.1960.053+0.0590.196^{+0.059}_{-0.053}). TOI-2145 b and TOI-2497 b both orbit subgiant host stars (3.8 << log\log g <<4.0), but these planets show no sign of inflation despite very high levels of irradiation. The lack of inflation may be explained by the high mass of the planets; 5.350.35+0.325.35^{+0.32}_{-0.35} MJ_{\rm J} (TOI-2145 b) and 5.21±0.525.21\pm0.52 MJ_{\rm J} (TOI-2497 b). These six new discoveries contribute to the larger community effort to use {\it TESS} to create a magnitude-complete, self-consistent sample of giant planets with well-determined parameters for future detailed studies.Comment: 20 Pages, 6 Figures, 8 Tables, Accepted by MNRA
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