1,068 research outputs found

    A Principal Component Analysis of the 3B Gamma-Ray Burst Data

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    We have carried out a principal component analysis for 625 gamma-ray bursts in the BATSE 3B catalog for which non-zero values exist for the nine measured variables. This shows that only two out of the three basic quantities of duration, peak flux and fluence are independent, even if this relation is strongly affected by instrumental effects, and these two account for 91.6% of the total information content. The next most important variable is the fluence in the fourth energy channel (at energies above 320 keV). This has a larger variance and is less correlated with the fluences in the remaining three channels than the latter correlate among themselves. Thus a separate consideration of the fourth channel, and increased attention on the related hardness ratio H43H43 appears useful for future studies. The analysis gives the weights for the individual measurements needed to define a single duration, peak flux and fluence. It also shows that, in logarithmic variables, the hardness ratio H32H32 is significantly correlated with peak flux, while H43H43 is significantly anticorrelated with peak flux. The principal component analysis provides a potentially useful tool for estimating the improvement in information content to be achieved by considering alternative variables or performing various corrections on available measurementsComment: Ap.J., accepted 12/9/97; revised version contains a new appendix, somewhat expanded discussion; latex, aaspp4, 15 page

    GLAST Prospects for Swift-Era Afterglows

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    We calculate the GeV spectra of GRB afterglows produced by inverse Compton scattering of the sub-MeV emission of these objects. We improve on earlier treatments by using refined afterglow parameters and new model developments motivated by recent Swift observations. We present time-dependent GeV spectra for standard, constant parameter models, as well as for models with energy injection and with time-varying parameters, for a range of burst parameters. We evaluate the limiting redshift to which such afterglows can be detected by the GLAST LAT, as well as AGILE.Comment: 19 pages, 5 figures, ApJ, in pres

    Spectra of Unsteady Wind Models of Gamma-Ray Bursts

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    We calculate the spectra expected from unsteady relativistic wind models of gamma-ray bursts, suitable for events of arbitrary duration. The spectral energy distribution of the burst is calculated over photon energies spanning from eV to TeV, for a range of event durations and variability timescales. The relative strength of the emission at different wavelengths can provide valuable information on the particle acceleration, radiation mechanisms and the possible types of models.Comment: 10 pages, 2 postscript figures included, uses aaspp4.sty. Accepted for publication in the Astrophysical Journal Letters. Also available at http://www.astro.psu.edu/users/hara/Preprints/xxx_sub.p

    Rising Through the Ranks: Women in War

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    This book will examine the evolving role of American women in the military, contrasting the Vietnam experiences with those of the Persian Gulf War, and including the Panama, Libya, and Grenada military actions. Beginning with the historical tradition of women in the United States military, the study will focus on changes in American society brought about by the Women\u27s Rights Movement and America\u27s involvement in Vietnam and how both affected women in the military. A discussion of the aftermath of the Persian Gulf War will concentrate on the Presidential Commission on the Assignment of Women in the Armed Forces and will conclude with an analysis of the Commission\u27s findings and the subsequent effects on American women in the military

    A Planning Pipeline for Large Multi-Agent Missions

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    In complex multi-agent applications, human operators are often tasked with planning and managing large heterogeneous teams of humans and autonomous vehicles. Although the use of these autonomous vehicles broadens the scope of meaningful applications, many of their systems remain unintuitive and difficult to master for human operators whose expertise lies in the application domain and not at the platform level. Current research focuses on the development of individual capabilities necessary to plan multi-agent missions of this scope, placing little emphasis on the integration of these components in to a full pipeline. The work presented in this paper presents a complete and user-agnostic planning pipeline for large multiagent missions known as the HOLII GRAILLE. The system takes a holistic approach to mission planning by integrating capabilities in human machine interaction, flight path generation, and validation and verification. Components modules of the pipeline are explored on an individual level, as well as their integration into a whole system. Lastly, implications for future mission planning are discussed

    Haec fortis sequitur illam indocti possident: A linguistic analysis of demonstratives in genres of early Latin fragments

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    This study examines the claim that demonstratives are used more frequently in Latin comedies than in other genres (Karakasis, 2014; Palmer, 1975), as well as additional hypotheses regarding the use of demonstratives within this language. To examine these claims, I created a corpus composed of fragments of Early Latin authors of comedic, tragic, and non-dramatic works. I examined demonstratives within this corpus for frequency, form, syntactic role, affective force, co-occurrence with personal pronouns, and use in multimembral demonstrative sets. This study provides the first quantitative evaluation of demonstrative use for often neglected authors of Early Latin. It also identifies those theories regarding demonstrative use that have more support within this time and suggests why these theories might hold true and how they might impact the overall demonstrative count for comedy, tragedy, non-dramatic works, or Latin as a whole

    Improving Human/Autonomous System Teaming Through Linguistic Analysis

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    An area of increasing interest for the next generation of aircraft is autonomy and the integration of increasingly autonomous systems into the national airspace. Such integration requires humans to work closely with autonomous systems, forming human and autonomous agent teams. The intention behind such teaming is that a team composed of both humans and autonomous agents will operate better than homogenous teams. Procedures exist for licensing pilots to operate in the national airspace system and current work is being done to define methods for validating the function of autonomous systems, however there is no method in place for assessing the interaction of these two disparate systems. Moreover, currently these systems are operated primarily by subject matter experts, limiting their use and the benefits of such teams. Providing additional information about the ongoing mission to the operator can lead to increased usability and allow for operation by non-experts. Linguistic analysis of the context of verbal communication provides insight into the intended meaning of commonly heard phrases such as "What's it doing now?" Analyzing the semantic sphere surrounding these common phrases enables the prediction of the operator's intent and allows the interface to supply the operator's desired information

    Properties of the intermediate type of gamma-ray bursts

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    Gamma-ray bursts can be divided into three groups ("short", "intermediate", "long") with respect to their durations. The third type of gamma-ray bursts - as known - has the intermediate duration. We show that the intermediate group is the softest one. An anticorrelation between the hardness and the duration is found for this subclass in contrast to the short and long groups.Comment: In Sixteenth Maryland Astrophysics Conferenc
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