13 research outputs found
Signals for Lorentz Violation in Electrodynamics
An investigation is performed of the Lorentz-violating electrodynamics
extracted from the renormalizable sector of the general Lorentz- and
CPT-violating standard-model extension. Among the unconventional properties of
radiation arising from Lorentz violation is birefringence of the vacuum. Limits
on the dispersion of light produced by galactic and extragalactic objects
provide bounds of 3 x 10^{-16} on certain coefficients for Lorentz violation in
the photon sector. The comparative spectral polarimetry of light from
cosmologically distant sources yields stringent constraints of 2 x 10^{-32}.
All remaining coefficients in the photon sector are measurable in
high-sensitivity tests involving cavity-stabilized oscillators. Experimental
configurations in Earth- and space-based laboratories are considered that
involve optical or microwave cavities and that could be implemented using
existing technology.Comment: 23 pages REVTe
Linking domain and situated motivation for writing with writing performance and experiences
Writing motivation, in terms of students' attitudes, values, beliefs, and goals, has a significant influence on writing achievement. However, much remains to be discovered about how this relationship unfolds over time, is affected by writing experiences, and is differentiated by general and context specific motivation measures. This presentation will report findings from a study conducted with nearly 750 students in grades 4 through 12 in two states that was designed to examine the connections between general and contextualised writing motivation, frequency and types of writing experiences, and writing performance reported by teachers and measured independently through trait scoring