Newtonian gravity and resonance on de-Sitter branes

A dS brane on the boundary between two five-dimensional spacetimes is determined. We consider asymmetric scenarios with AdS${}_5$ vacua at each side of the dS brane; and as a result, a resonant mode inside of the spectrum of the gravitational fluctuations is found. We analyze the deviations to the Newton potential generated by the gravitational excitations, finding that, for scenarios with large values of the cosmological constants, the contribution of the resonant mode is exponentially suppressed. However, when one of the vacua is null, the resonant mode belongs to the light states set of the gravitational fluctuations and five-dimensional gravity is recovered on the dS brane.Comment: 6 pages, 2 figure

Close to the edge: hierarchy in a double braneworld

We show that the hierarchy between the Planck and the weak scales can follow from the tendency of gravitons and fermions to localize at different edges of a thick double wall embedded in an $AdS_5$ spacetime without reflection symmetry. This double wall is a stable BPS thick-wall solution with two sub-walls located at its edges; fermions are coupled to the scalar field through Yukawa interactions, but the the lack of reflection symmetry forces them to be localized in one of the sub-walls. We show that the graviton zero-mode wavefunction is suppressed in the fermion edge by an exponential function of the distance between the sub-walls, and that the massive modes decouple so that Newtonian gravity is recuperated.Comment: Some typos corrected, references adde

Gauge field localization on brane worlds

We consider the effects of spacetime curvature and brane thickness on the localization of gauge fields on a brane via kinetic terms induced by localized fermions. We find that in a warped geometry with and infinitely thin brane, both the infrared and the ultraviolet behavior of the electromagnetic propagator are affected, providing a more stringent bound on the brane's tension than that coming from the requirement of four-dimensional gravity on the brane. On the other hand, for a thick wall in a flat spacetime, where the fermions are localized by means of a Yukawa coupling, we find that 4-dimensional electromagnetism is recovered in a region bounded from above by the same critical distance appearing in the thin case, but also from below by a new scale related to the brane's thickness and the electromagnetic couplings.Comment: 7 page

Professional Development Principles for Teachers of English Language Learners

Since effective professional development is logically embedded in the reality of schools and teachers‘ work, it stands to reason that the principal would consider that reality for teachers of English language learners (ELL). Certainly, in general, professional development would incorporate principles of adult learning as reported by Knowles (1980): (1) adult learners need to be self-directed; (2) they display readiness to learn when they have a perceived need; and (3) they desire immediate application of new skills and knowledge. Based on adult learning theory, then, principals would provide teachers of ELLs professional development that addresses a need for self-direction, that addresses their particular needs, and that addresses the desire to apply what is learned. Time and created situations whereby teachers can dialogue with other teachers and principals can dialogue with other principals is critical for the effective application of the knowledge gained in professional development sessions and afterward as well