6,054 research outputs found
Extremal Isolated Horizons: A Local Uniqueness Theorem
We derive all the axi-symmetric, vacuum and electrovac extremal isolated
horizons. It turns out that for every horizon in this class, the induced metric
tensor, the rotation 1-form potential and the pullback of the electromagnetic
field necessarily coincide with those induced by the monopolar, extremal
Kerr-Newman solution on the event horizon. We also discuss the general case of
a symmetric, extremal isolated horizon. In particular, we analyze the case of a
two-dimensional symmetry group generated by two null vector fields. Its
relevance to the classification of all the symmetric isolated horizons,
including the non-extremal once, is explained.Comment: 22 pages, page size changed, typos and equations (142), (143a)
corrected, PACS number adde
Maneuvering the Dual Mode Manned/Automated Lunar Roving Vehicle, June 1969 - March 1970
Digital maps of hazards to movement for dual mode Lunar Roving Vehicl
Development and Validation of the Colorado Learning Attitudes about Science Survey for Experimental Physics
As part of a comprehensive effort to transform our undergraduate physics
laboratories and evaluate the impacts of these efforts, we have developed the
Colorado Learning Attitudes about Science Survey for Experimental Physics
(E-CLASS). The E-CLASS assesses the changes in students' attitudes about a
variety of scientific laboratory practices before and after a lab course and
compares attitudes with perceptions of the course grading requirements and
laboratory practices. The E-CLASS is designed to give researchers insight into
students' attitudes and also to provide actionable evidence to instructors
looking for feedback on their courses. We present the development, validation,
and preliminary results from the initial implementation of the survey in three
undergraduate physics lab courses.Comment: 8 pages, 4 figures, 1 table, submitted to 2012 PERC Proceeding
Flux density measurements of GPS candidate pulsars at 610 MHz using interferometric imaging technique
We conducted radio interferometric observations of six pulsars at 610 MHz
using the Giant Metrewave Radio Telescope (GMRT). All these objects were
claimed or suspected to be the gigahertz-peaked spectra (GPS) pulsars. For a
half of the sources in our sample the interferometric imaging provides the only
means to estimate their flux at 610 MHz due to a strong pulse
scatter-broadening. In our case, these pulsars have very high dispersion
measure values and we present their spectra containing for the first time
low-frequency measurements. The remaining three pulsars were observed at low
frequencies using the conventional pulsar flux measurement method. The
interferometric imaging technique allowed us to re-examine their fluxes at 610
MHz. We were able to confirm the GPS feature in the PSR B182313 spectrum and
select a GPS candidate pulsar. These results clearly demonstrate that the
interferometric imaging technique can be successfully applied to estimate flux
density of pulsars even in the presence of strong scattering.Comment: 7 pages, 3 tables, 5 figures, accepted for publication in MNRA
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