1,720,972 research outputs found
VERITAS Observation of GRB060501
No full textMentor: Henric Krawczynski
From the Washington University Undergraduate Research Digest: WUURD, Volume 2, Issue 2, Spring 2007. Published by the Office of Undergraduate Research.
Henry Biggs, Director of Undergraduate Research and Associate Dean in the College of Arts & Sciences; Joy Zalis Kiefer, Undergraduate Research Coordinator, Editor, and Assistant Dean in the College of Arts & Sciences; Kristin Sobotka, Co-editor
Utilizing Fractionated Space Mission Design and Small Satellites for a Next Generation Gamma Ray Burst Observatory
Get PDFSince the discovery of Gamma Ray Bursts (GRBs) by the Vela satellite, the field of GRB astronomy has been rapidly evolving in order to explain the most catastrophic event in the universe. Missions over the last two decades have pinpointed GRBs as extragalactic sources as well as shed insight on their nature. NASA’s recent Swift mission provides a platform for multiwavelength analysis of GRBs and their afterglow as well as transmitting GRB position data to other observatories. A future mission can compliment Swift’s array of multiwavelength instrumentation as well as providing more rapid, accurate GRB position data. A fractionated, small satellite mission can utilize the scale of small satellites to rapidly slew to a GRB target and then use stereoscopic observation and short baselines to further pinpoint the GRB position. A frac- tionated mission design places various scientific instrumentation as the primary payload on each individual satellite, providing robust performance and a greater field of view by decentralization. Additionally, future space interferometry missions will employ formation flying and fractionated design. A fractionated, small satellite mission will provide a cost effective proof of concept and valuable data to the scientific community
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Modern Assessment of the High-Energy Background Environment at Small Atmospheric Depths Using the X-Calibur X-Ray Polarimeter and Its Implications
Get PDFSince the discovery of cosmic rays, Earth\u27s upper atmosphere at depths of 1-10 g cm2 has been used for balloon-borne observations probing the high-energy universe. However, the interaction of cosmic rays with the earth atmosphere generates numerous particles, each with their own flux and interaction physics that contribute to instrument background. In Fall 2014, the X-Calibur X-ray polarimeter designed and built at Washington University in St. Louis was launched from Ft. Sumner, New Mexico. While no astrophysical observation was performed as a result of a failure in telescope mechanisms, X-Calibur was able to record hours of instrument background with an energy resolution of E ~keV at a depth of 3.45 g cm2. Using the 2014 X-Calibur data, existing observations of atmospheric gamma-rays, hadrons, and leptons, and the MEGAlib/GEANT particle transport simulation environments, I develop and perform preliminarily validation of detailed background models in the regime of 1 keV-100 GeV. The models are generally constructed by involving experimental data with atmospheric mass and composition models rather than integration of source/emission functions or complete Monte Carlo simulation of cosmic rays entering at the top of the atmosphere. Notably, these models are derived as functions of energy, off-zenith angle to degree precision, geomagnetic latitude, and solar modulation factor enabling predictions of instrument background for future X-Calibur flights. These background models are also used to optimize the shielding conguration through additional passive material or active components as constrained by the existing active shiel
Proximity Operations and Rapid Integration with the Akoya and Bandit Nanosatellites
No full textMentor: Michael A. Swartwout
From the Washington University Undergraduate Research Digest: WUURD, Volume 3, Issue 1, Fall 2007. Published by the Office of Undergraduate Research.
Henry Biggs, Director of Undergraduate Research and Associate Dean in the College of Arts & Sciences; Joy Zalis Kiefer, Undergraduate Research Coordinator, Co-editor, and Assistant Dean in the College of Arts & Sciences; Kristin Sobotka, Editor
Electric Propulsion Induced Secondary Mass Spectroscopy
Get PDFA document highlights a means to complement remote spectroscopy while also providing in situ surface samples without a landed system. Historically, most compositional analysis of small body surfaces has been done remotely by analyzing reflection or nuclear spectra. However, neither provides direct measurement that can unambiguously constrain the global surface composition and most importantly, the nature of trace composition and second-phase impurities. Recently, missions such as Deep Space 1 and Dawn have utilized electric propulsion (EP) accelerated, high-energy collimated beam of Xe+ ions to propel deep space missions to their target bodies. The energies of the Xe+ are sufficient to cause sputtering interactions, which eject material from the top microns of a targeted surface. Using a mass spectrometer, the sputtered material can be determined. The sputtering properties of EP exhaust can be used to determine detailed surface composition of atmosphereless bodies by electric propulsion induced secondary mass spectroscopy (EPI-SMS). EPI-SMS operation has three high-level requirements: EP system, mass spectrometer, and altitude of about 10 km. Approximately 1 keV Xe+ has been studied and proven to generate high sputtering yields in metallic substrates. Using these yields, first-order calculations predict that EPI-SMS will yield high signal-to-noise at altitudes greater than 10 km with both electrostatic and Hall thrusters
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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