467 research outputs found

    Privacy and Direct Mail Advertising

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    Code wars: steganography, signals intelligence, and terrorism

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    This paper describes and discusses the process of secret communication known as steganography. The argument advanced here is that terrorists are unlikely to be employing digital steganography to facilitate secret intra-group communication as has been claimed. This is because terrorist use of digital steganography is both technically and operationally implausible. The position adopted in this paper is that terrorists are likely to employ low-tech steganography such as semagrams and null ciphers instead

    Validation of Twelve Small Kepler Transiting Planets in the Habitable Zone

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    We present an investigation of twelve candidate transiting planets from Kepler with orbital periods ranging from 34 to 207 days, selected from initial indications that they are small and potentially in the habitable zone (HZ) of their parent stars. Few of these objects are known. The expected Doppler signals are too small to confirm them by demonstrating that their masses are in the planetary regime. Here we verify their planetary nature by validating them statistically using the BLENDER technique, which simulates large numbers of false positives and compares the resulting light curves with the Kepler photometry. This analysis was supplemented with new follow-up observations (high-resolution optical and near-infrared spectroscopy, adaptive optics imaging, and speckle interferometry), as well as an analysis of the flux centroids. For eleven of them (KOI-0571.05, 1422.04, 1422.05, 2529.02, 3255.01, 3284.01, 4005.01, 4087.01, 4622.01, 4742.01, and 4745.01) we show that the likelihood they are true planets is far greater than that of a false positive, to a confidence level of 99.73% (3 sigma) or higher. For KOI-4427.01 the confidence level is about 99.2% (2.6 sigma). With our accurate characterization of the GKM host stars, the derived planetary radii range from 1.1 to 2.7 R_Earth. All twelve objects are confirmed to be in the HZ, and nine are small enough to be rocky. Excluding three of them that have been previously validated by others, our study doubles the number of known rocky planets in the HZ. KOI-3284.01 (Kepler-438b) and KOI-4742.01 (Kepler-442b) are the planets most similar to the Earth discovered to date when considering their size and incident flux jointly.Comment: 27 pages in emulateapj format, including tables and figures. To appear in The Astrophysical Journa

    The Grizzly, February 13, 1981

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    Water Crisis Worsens: TCE Also a Problem • Pett Leaving Economics Department • Mobley Breaks Basketball Record • News Briefs: Meistersingers concert in Oreland; Ursinus professor published • Departmental Focus: English Department; History Department • Orientation Committee Applications Being Taken • 1981 Fraternity Pledge Classes • Music News • Female Artists Topic of Forum • Coffeehouse: A Folk Touch • Candidates for USGA Offices • Women\u27s B-Ball Undefeated 9 Straight • Tight Season Ahead for Intramural B-Ball • Badminton Team Playin\u27 Tough • Hoopsters Claim Two More Victims • Grizzly Grapplers Mark at 7-4-1 • Aquabears Dunk Foes: Swimmers Living Up to .500 Goalhttps://digitalcommons.ursinus.edu/grizzlynews/1052/thumbnail.jp

    Exoplanet Characterization by Proxy: A Transiting 2.15 R_⊕ Planet near the Habitable Zone of the Late K Dwarf Kepler-61

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    We present the validation and characterization of Kepler-61b: a 2.15 R_⊕ planet orbiting near the inner edge of the habitable zone of a low-mass star. Our characterization of the host star Kepler-61 is based upon a comparison with a set of spectroscopically similar stars with directly measured radii and temperatures. We apply a stellar prior drawn from the weighted mean of these properties, in tandem with the Kepler photometry, to infer a planetary radius for Kepler-61b of 2.15 ± 0.13 R_⊕ and an equilibrium temperature of 273 ± 13 K (given its period of 59.87756 ± 0.00020 days and assuming a planetary albedo of 0.3). The technique of leveraging the physical properties of nearby "proxy" stars allows for an independent check on stellar characterization via the traditional measurements with stellar spectra and evolutionary models. In this case, such a check had implications for the putative habitability of Kepler-61b: the planet is 10% warmer and larger than inferred from K-band spectral characterization. From the Kepler photometry, we estimate a stellar rotation period of 36 days, which implies a stellar age of >1 Gyr. We summarize the evidence for the planetary nature of the Kepler-61 transit signal, which we conclude is 30,000 times more likely to be due to a planet than a blend scenario. Finally, we discuss possible compositions for Kepler-61b with a comparison to theoretical models as well as to known exoplanets with similar radii and dynamically measured masses

    The Science Case for an Extended Spitzer Mission

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    Although the final observations of the Spitzer Warm Mission are currently scheduled for March 2019, it can continue operations through the end of the decade with no loss of photometric precision. As we will show, there is a strong science case for extending the current Warm Mission to December 2020. Spitzer has already made major impacts in the fields of exoplanets (including microlensing events), characterizing near Earth objects, enhancing our knowledge of nearby stars and brown dwarfs, understanding the properties and structure of our Milky Way galaxy, and deep wide-field extragalactic surveys to study galaxy birth and evolution. By extending Spitzer through 2020, it can continue to make ground-breaking discoveries in those fields, and provide crucial support to the NASA flagship missions JWST and WFIRST, as well as the upcoming TESS mission, and it will complement ground-based observations by LSST and the new large telescopes of the next decade. This scientific program addresses NASA's Science Mission Directive's objectives in astrophysics, which include discovering how the universe works, exploring how it began and evolved, and searching for life on planets around other stars.Comment: 75 pages. See page 3 for Table of Contents and page 4 for Executive Summar

    Exoplanet characterization by proxy: a transiting 2.15 R⊕ planet near the habitable zone of the late K dwarf Kepler-61

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    We present the validation and characterization of Kepler-61b: a 2.15 R ⊕ planet orbiting near the inner edge of the habitable zone of a low-mass star. Our characterization of the host star Kepler-61 is based upon a comparison with a set of spectroscopically similar stars with directly measured radii and temperatures. We apply a stellar prior drawn from the weighted mean of these properties, in tandem with the Kepler photometry, to infer a planetary radius for Kepler-61b of 2.15 ± 0.13 R ⊕ and an equilibrium temperature of 273 ± 13 K (given its period of 59.87756 ± 0.00020 days and assuming a planetary albedo of 0.3). The technique of leveraging the physical properties of nearby 'proxy' stars allows for an independent check on stellar characterization via the traditional measurements with stellar spectra and evolutionary models. In this case, such a check had implications for the putative habitability of Kepler-61b: the planet is 10% warmer and larger than inferred from K-band spectral characterization. From the Kepler photometry, we estimate a stellar rotation period of 36 days, which implies a stellar age of >1 Gyr. We summarize the evidence for the planetary nature of the Kepler-61 transit signal, which we conclude is 30,000 times more likely to be due to a planet than a blend scenario. Finally, we discuss possible compositions for Kepler-61b with a comparison to theoretical models as well as to known exoplanets with similar radii and dynamically measured masses

    The Grizzly, October 10, 1980

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    Alternative Housing Investigated • Unchanged since 1960: Activity Fee Increase Likely • Freshman Class Select Officers • Work Stalled On Campus Beautification • Bermans Give Sculpture To College • Ursinus News In Brief: Student chemistry group honored; Study skills workshop to be repeated; College appoints pol sci lecturer • Off-Campus Houses Rewired • Fast Method Discovered for Wismer • African Politics Subject of Oct. 15 Forum • IF Council, USGA Host Fall Picnic • Inactive Alarm System Questioned • Steranko Plays To Sparse Crowd • The Art of Procrastination • Toga! Toga! Toga! • New Ritter Center Dedicated • How To Get To Philly Without A Car • Guide To Ursinus Vocabulary • Science Fiction Books Discussion Offered • Lantern Needs Help • CLC Reveals Findings From Survey • Homecoming Candidates • Three Intramural Teams Clinch Playoff Spot • Booters Take Two • Hockey\u27s Unbeaten Streak Broken • X-Country Places 2nd At Mansfieldhttps://digitalcommons.ursinus.edu/grizzlynews/1043/thumbnail.jp
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