3,885 research outputs found
Gamma-ray emission associated with Cluster-scale AGN Outbursts
Recent observations have revealed the existence of enormously energetic
~10^61 erg AGN outbursts in three relatively distant galaxy clusters. These
outbursts have produced bubbles in the intra-cluster medium, apparently
supported by pressure from relativistic particles and/or magnetic fields. Here
we argue that if > GeV particles are responsible then these particles are very
likely protons and nuclei, rather than electrons, and that the gamma-ray
emission from these objects, arising from the interactions of these hadrons in
the intra-cluster medium, may be marginally detectable with instruments such as
GLAST and HESS.Comment: 8 pages, 4 figures, accepted by MNRA
Preparation of pigments for space-stable thermal control coatings Interim summary report, 1 Jun. 1968 - 30 Apr. 1969
Control of vapor phase reaction kinetics to produce pigments by homogeneous nucleatio
Metallic phase of the quantum Hall effect in four-dimensional space
We study the phase diagram of the quantum Hall effect in four-dimensional
(4D) space. Unlike in 2D, in 4D there exists a metallic as well as an
insulating phase, depending on the disorder strength. The critical exponent
of the diverging localization length at the quantum Hall
insulator-to-metal transition differs from the semiclassical value of
4D Anderson transitions in the presence of time-reversal symmetry. Our
numerical analysis is based on a mapping of the 4D Hamiltonian onto a 1D
dynamical system, providing a route towards the experimental realization of the
4D quantum Hall effect.Comment: 4+epsilon pages, 3 figure
The Differential Impact of a Basic Public Speaking Course on Perceived Communication Competencies in Class, Work, and Social Contexts
Communication departments generally choose between a public speaking and a hybrid course of their basic course. Previous research has shown that students\u27 perceptions of their communication competencies increase after completing a hybrid course (Ford & Wolvin, 1992, 1993). After noting similarities between public speaking and hybrid courses, this study examines students\u27 perceptions of their competencies after completing a public a speaking course.
Results indicated that students\u27 perceptions of their competencies changed significantly in class, work, and social contacts in such areas as public speaking, interpersonal and group communication, interviewing, listening, and self-confidence. The largest gains were in perceptions of their classroom competencies
Development of a high-altitude airborne dial system: The Lidar Atmospheric Sensing Experiment (LASE)
The ability of a Differential Absorption Lidar (DIAL) system to measure vertical profiles of H2O in the lower atmosphere was demonstrated both in ground-based and airborne experiments. In these experiments, tunable lasers were used that required real-time experimenter control to locate and lock onto the atmospheric H2O absorption line for the DIAL measurements. The Lidar Atmospheric Sensing Experiment (LASE) is the first step in a long-range effort to develop and demonstrate an autonomous DIAL system for airborne and spaceborne flight experiments. The LASE instrument is being developed to measure H2O, aerosol, and cloud profiles from a high-altitude ER-2 (extended range U-2) aircraft. The science of the LASE program, the LASE system design, and the expected measurement capability of the system are discussed
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