12,983 research outputs found

    Spherical solid-propellant rocket motor Patent

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    Spherical solid propellant rocket engine desig

    Ground-based NIR emission spectroscopy of HD189733b

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    We investigate the K and L band dayside emission of the hot-Jupiter HD 189733b with three nights of secondary eclipse data obtained with the SpeX instrument on the NASA IRTF. The observations for each of these three nights use equivalent instrument settings and the data from one of the nights has previously reported by Swain et al (2010). We describe an improved data analysis method that, in conjunction with the multi-night data set, allows increased spectral resolution (R~175) leading to high-confidence identification of spectral features. We confirm the previously reported strong emission at ~3.3 microns and, by assuming a 5% vibrational temperature excess for methane, we show that non-LTE emission from the methane nu3 branch is a physically plausible source of this emission. We consider two possible energy sources that could power non-LTE emission and additional modelling is needed to obtain a detailed understanding of the physics of the emission mechanism. The validity of the data analysis method and the presence of strong 3.3 microns emission is independently confirmed by simultaneous, long-slit, L band spectroscopy of HD 189733b and a comparison star.Comment: ApJ accepte

    Phase-dependent spectra in a driven two-level atom

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    We propose a method to observe phase-dependent spectra in resonance fluorescence, employing a two-level atom driven by a strong coherent field and a weak, amplitude-fluctuating field. The spectra are similar to those which occur in a squeezed vacuum, but avoid the problem of achieving squeezing over a 4π4\pi solid angle. The system shows other interesting features, such as pronounced gain without population inversion.Comment: 4 pages and 4 figures. Submitted to Phys. Rev. Let

    Le Murmure Des Vents : Murmuring Winds

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    https://digitalcommons.library.umaine.edu/mmb-ps/2402/thumbnail.jp

    High-Calcium Limestone Deposits of Cumberland Valley, Pennsylvania

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    Author Institution: University of Minnesota, Minneapolis, MinnesotaHigh-calcium limestones occur in the upper part of the New Market Formation, of Lower Middle Ordovician age, in Franklin and Cumberland Counties, Pennsylvania. The high-calcium facies of the New Market Formation is represented by sublithographic limestone or vaughanite, which probably formed in quiet water, low-energy environments such as intershoal lagoons, or in protected bays similar to the present-day Florida Bay environment. Rapid facies changes are characteristic of the strata. The better grade of stone lies in the upper 100 to 125 feet of the New Market Formation and averages 95-97% calcium carbonate. Silica and magnesia are about equal in amount as impurities. One high-calcium belt extends from the Maryland state line through Chambersburg and Newville to beyond Carlisle. The strata in this belt are structurally complex, which requires careful field study and core-drilling prior to exploitation. Stone suitable for blast-furnace flux is present in relatively large amounts, but stone for open-hearth use or portland cement requires more selective quarrying

    The First Data Release of the KODIAQ Survey

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    We present and make publicly available the first data release (DR1) of the Keck Observatory Database of Ionized Absorption toward Quasars (KODIAQ) survey. The KODIAQ survey is aimed at studying galactic and circumgalactic gas in absorption at high-redshift, with a focus on highly-ionized gas traced by OVI, using the HIRES spectrograph on the Keck-I telescope. KODIAQ DR1 consists of a fully-reduced sample of 170 quasars at 0.29 < z_em < 5.29 observed with HIRES at high resolution (36,000 <= R <= 103,000) between 2004 and 2012. DR1 contains 247 spectra available in continuum normalized form, representing a sum total exposure time of ~1.6 megaseconds. These co-added spectra arise from a total of 567 individual exposures of quasars taken from the Keck Observatory Archive (KOA) in raw form and uniformly processed using a HIRES data reduction package made available through the XIDL distribution. DR1 is publicly available to the community, housed as a higher level science product at the KOA. We will provide future data releases that make further QSOs, including those with pre-2004 observations taken with the previous-generation HIRES detectors.Comment: 14 pages, 9 figures, Submitted to AJ. All data products available at the Keck Observatory Archive beginning May 15, 2015. URL: https://koa.ipac.caltech.edu/applications/KODIA

    DeltaPhish: Detecting Phishing Webpages in Compromised Websites

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    The large-scale deployment of modern phishing attacks relies on the automatic exploitation of vulnerable websites in the wild, to maximize profit while hindering attack traceability, detection and blacklisting. To the best of our knowledge, this is the first work that specifically leverages this adversarial behavior for detection purposes. We show that phishing webpages can be accurately detected by highlighting HTML code and visual differences with respect to other (legitimate) pages hosted within a compromised website. Our system, named DeltaPhish, can be installed as part of a web application firewall, to detect the presence of anomalous content on a website after compromise, and eventually prevent access to it. DeltaPhish is also robust against adversarial attempts in which the HTML code of the phishing page is carefully manipulated to evade detection. We empirically evaluate it on more than 5,500 webpages collected in the wild from compromised websites, showing that it is capable of detecting more than 99% of phishing webpages, while only misclassifying less than 1% of legitimate pages. We further show that the detection rate remains higher than 70% even under very sophisticated attacks carefully designed to evade our system.Comment: Preprint version of the work accepted at ESORICS 201

    The Design and Operation of The Keck Observatory Archive

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    The Infrared Processing and Analysis Center (IPAC) and the W. M. Keck Observatory (WMKO) operate an archive for the Keck Observatory. At the end of 2013, KOA completed the ingestion of data from all eight active observatory instruments. KOA will continue to ingest all newly obtained observations, at an anticipated volume of 4 TB per year. The data are transmitted electronically from WMKO to IPAC for storage and curation. Access to data is governed by a data use policy, and approximately two-thirds of the data in the archive are public.Comment: 12 pages, 4 figs, 4 tables. Presented at Software and Cyberinfrastructure for Astronomy III, SPIE Astronomical Telescopes + Instrumentation 2014. June 2014, Montreal, Canad
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