15,635 research outputs found
An Optical Approach to the Dynamical Casimir Effect
We recently proposed a new approach to analyze the parametric resonance in a
vibrating cavity based on the analysis of classical optical paths. This
approach is used to examine various models of cavities with moving walls. We
prove that our method is useful to extract easily basic physical outcome.Comment: 9 page
Functionalizing self-assembled GaN quantum dot superlattices by Eu-implantation
Self-assembled GaN quantum dots (QDs) stacked in superlattices (SL) with AlN spacer layers were implanted with Europium ions to fluences of 1013, 1014, and 1015 cm−2. The damage level introduced in the QDs by the implantation stays well below that of thick GaN epilayers. For the lowest fluence, the structural properties remain unchanged after implantation and annealing while for higher fluences the implantation damage causes an expansion of the SL in the [0001] direction which increases with implantation fluence and is only partly reversed after thermal annealing at 1000 °C. Nevertheless, in all cases, the SL quality remains very good after implantation and annealing with Eu ions incorporated preferentially into near-substitutional cation sites. Eu3+ optical activation is achieved after annealing in all samples. In the sample implanted with the lowest fluence, the Eu3+ emission arises mainly from Eu incorporated inside the QDs while for the higher fluences only the emission from Eu inside the AlN-buffer, capping, and spacer layers is observed.
© 2010 American Institute of PhysicsFCT-PTDC/CTM/100756/2008program PESSOA EGIDE/GRICESFCT-SFRH/BD/45774/2008FCT-SFRH/BD/44635/200
Aplicabilidade de marcadores SSR em estudos genéticos em Gossypium Mustelinun Miers.
bitstream/CNPA/20279/1/COMTEC345.pd
Large deviations for non-uniformly expanding maps
We obtain large deviation results for non-uniformly expanding maps with
non-flat singularities or criticalities and for partially hyperbolic
non-uniformly expanding attracting sets. That is, given a continuous function
we consider its space average with respect to a physical measure and compare
this with the time averages along orbits of the map, showing that the Lebesgue
measure of the set of points whose time averages stay away from the space
average decays to zero exponentially fast with the number of iterates involved.
As easy by-products we deduce escape rates from subsets of the basins of
physical measures for these types of maps. The rates of decay are naturally
related to the metric entropy and pressure function of the system with respect
to a family of equilibrium states. The corrections added to the published
version of this text appear in bold; see last section for a list of changesComment: 36 pages, 1 figure. After many PhD students and colleagues having
pointed several errors in the statements and proofs, this is a correction to
published article answering those comments. List of main changes in a new
last sectio
Spontaneous symmetry breaking in amnestically induced persistence
We investigate a recently proposed non-Markovian random walk model
characterized by loss of memories of the recent past and amnestically induced
persistence. We report numerical and analytical results showing the complete
phase diagram, consisting of 4 phases, for this system: (i) classical
nonpersistence, (ii) classical persistence (iii) log-periodic nonpersistence
and (iv) log-periodic persistence driven by negative feedback. The first two
phases possess continuous scale invariance symmetry, however log-periodicity
breaks this symmetry. Instead, log-periodic motion satisfies discrete scale
invariance symmetry, with complex rather than real fractal dimensions. We find
for log-periodic persistence evidence not only of statistical but also of
geometric self-similarity.Comment: 4 pages, 2 color fig
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