35 research outputs found

    Simultaneous Exoplanet Characterization and deep wide-field imaging with a diffractive pupil telescope

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    High-precision astrometry can identify exoplanets and measure their orbits and masses, while coronagraphic imaging enables detailed characterization of their physical properties and atmospheric compositions through spectroscopy. In a previous paper, we showed that a diffractive pupil telescope (DPT) in space can enable sub-microarcsecond accuracy astrometric measurements from wide-field images by creating faint but sharp diffraction spikes around the bright target star. The DPT allows simultaneous astrometric measurement and coronagraphic imaging, and we discuss and quantify in this paper the scientific benefits of this combination for exoplanet science investigations: identification of exoplanets with increased sensitivity and robustness, and ability to measure planetary masses to high accuracy. We show how using both measurements to identify planets and measure their masses offers greater sensitivity and provides more reliable measurements than possible with separate missions, and therefore results in a large gain in mission efficiency. The combined measurements reliably identify potentially habitable planets in multiple systems with a few observations, while astrometry or imaging alone would require many measurements over a long time baseline. In addition, the combined measurement allows direct determination of stellar masses to percent-level accuracy, using planets as test particles. We also show that the DPT maintains the full sensitivity of the telescope for deep wide-field imaging, and is therefore compatible with simultaneous scientific observations unrelated to exoplanets. We conclude that astrometry, coronagraphy, and deep wide-field imaging can be performed simultaneously on a single telescope without significant negative impact on the performance of any of the three techniques.Comment: 15 pages, 6 figures. This second paper, following the paper describing the diffractive pupil telescope (DPT) astrometric technique, shows how simultaneous astrometry and coronagraphy observations, enabled by the DPT concept, constrain the orbital parameters and mass of exoplanet

    Temporal Associations between Psychological and Physical Intimate Partner Violence: A Cross-Lag Analysis

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    The present study examined the relationship between psychological and physical forms of intimate partner violence (IPV) across four waves of data during the developmental period of young adulthood. The links from early psychological aggression to later physical aggression and from early physical aggression to later psychological aggression across waves were tested while controlling for their cross-time stabilities and concurrent associations. IPV data were collected annually from 434 young adult respondents involved in a romantic relationship at least once during the respective years from the ages of 22-25. On average, participants provided IPV data for three out of the four years covered by the study (M = 2.82; SD = 1.14). Results of a cross-lagged SEM model indicated significant cross-time stabilities as well as significant, positive concurrent associations for both forms of aggression. Most important to this study were the findings that, controlling for these stabilities and concurrent associations, early psychological aggression was a consistent positive predictor of later physical aggression across waves whereas the opposite direction from early physical aggression to later psychological aggression was either non-significant or significant and negative

    Systems Engineering on the James Webb Space Telescope

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    The James Web Space Telescope (JWST) is a large, infrared-optimized space telescope scheduled for launch in 2014. System-level verification of critical performance requirements will rely on integrated observatory models that predict the wavefront error accurately enough to verify that allocated top-level wavefront error of 150 nm root-mean-squared (rms) through to the wave-front sensor focal plane is met. This paper describes the systems engineering approach used on the JWST through the detailed design phase

    Survival probability of mutually killing Brownian motions and the O'Connell process

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    Recently O'Connell introduced an interacting diffusive particle system in order to study a directed polymer model in 1+1 dimensions. The infinitesimal generator of the process is a harmonic transform of the quantum Toda-lattice Hamiltonian by the Whittaker function. As a physical interpretation of this construction, we show that the O'Connell process without drift is realized as a system of mutually killing Brownian motions conditioned that all particles survive forever. When the characteristic length of interaction killing other particles goes to zero, the process is reduced to the noncolliding Brownian motion (the Dyson model).Comment: v2: AMS-LaTeX, 20 pages, 2 figures, minor corrections made for publication in J. Stat. Phy

    The Science Performance of JWST as Characterized in Commissioning

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    This paper characterizes the actual science performance of the James Webb Space Telescope (JWST), as determined from the six month commissioning period. We summarize the performance of the spacecraft, telescope, science instruments, and ground system, with an emphasis on differences from pre-launch expectations. Commissioning has made clear that JWST is fully capable of achieving the discoveries for which it was built. Moreover, almost across the board, the science performance of JWST is better than expected; in most cases, JWST will go deeper faster than expected. The telescope and instrument suite have demonstrated the sensitivity, stability, image quality, and spectral range that are necessary to transform our understanding of the cosmos through observations spanning from near-earth asteroids to the most distant galaxies.Comment: 5th version as accepted to PASP; 31 pages, 18 figures; https://iopscience.iop.org/article/10.1088/1538-3873/acb29

    Rural Cooperatives Magazine

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    Features- Ownership succession crucial for rural america; Groomed for success; Expanding your customer base; Climbing the hill; Agriculture of the Middle: Opportunity for co-ops; Tomato co-ops help craft better food safety standards; Sailing turbulent seas; Co-op ideas can help educatio
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