12 research outputs found
Quantum Polarization of D4-branes
The low energy effective field theory of type II D4-branes coupled to bulk
supergravity fields is used to investigate {\it quantum} effects for D4-branes
in the D0 supergravity background. Classically, the D4-branes are unaffected by
this background. However, quantum (one-loop) effects are argued to lead to an
induced density of D0-brane charge; e.g., D0-multipole moments on the D4-brane.
The effect is divergent in field theory, but is expected to be cut-off
naturally by stringy corrections.Comment: 15 pages, Some changes in the implications for string theory after
discussions with Friedel Eppl
Counting Supertubes
The quantum states of the supertube are counted by directly quantizing the
linearized Born-Infeld action near the round tube. The result is an entropy , in accord with conjectures in the
literature. As a result, supertubes may be the generic D0-F1 bound state. Our
approach also shows directly that supertubes are marginal bound states with a
discrete spectrum. We also discuss the relation to recent suggestions of Mathur
et al involving three-charge black holes.Comment: 15 pages, v2: reference corrected; v3: few corrections and explicit
derivation of a relation are added to appendix
Very high quality factor measured in annealed fused silica
We present the results of quality factor measurements for rod samples made of
fused silica. To decrease the dissipation we annealed our samples. The highest
quality factor that we observed was for a mode at
384 Hz. This is the highest published value of in fused silica measured to
date.Comment: 8 pages, 2 figure
Supertubes, black strings and D-brane systems
In this dissertation, we focus on aspects of String Theory and General Relativity. The study of objects of various spatial dimensions, or branes, have become an intrinsic part of modern String Theory. Here, we focus on three concrete topics concerning the physics of branes: supertubes, quantum D-brane polarization, and the stability of black branes. We devote the final part of this work to the study of fast travel in 3+1 dimensional spherically symmetric configurations
Why is Brazil enriching uranium?
In Brazil construction began in 1971 on Angra 1, a 626 MW Westinghouse pressurized water reactor (PWR). It was completed in 1984. Later, Angra 2 (a Kraftwerk Union PWR) achieved commercial operation in 2000. Brazil is considering the construction of seven nuclear power plants over the next 15 years. In preparation for this nuclear industry expansion, Brazil is building a uranium enrichment facility to provide nuclear fuel for Angra 1 and 2 starting in 2010 at Resende in the state of Rio de Janeiro, and collated with nuclear fuel fabrication facilities. This paper investigates whether the Resende Enrichment Facility will be able to provide uranium enrichment services at a cost lower than the international market price. We find that while Brazil is unlikely to be internationally competitive in the enrichment market, the Resende Enrichment Facility completes the front end of Brazil's nuclear fuel cycle. This assures uninterrupted nuclear fuel to its currently operating light water reactors, while providing the option of expanding capacity, lowering cost, and competing in the international nuclear fuel market after 2020.