Initial pseudo-steady state & asymptotic KPZ universality in semiconductor on polymer deposition

The Kardar-Parisi-Zhang (KPZ) class is a paradigmatic example of universality in nonequilibrium phenomena, but clear experimental evidences of asymptotic 2D-KPZ statistics are still very rare, and far less understanding stems from its short-time behavior. We tackle such issues by analyzing surface fluctuations of CdTe films deposited on polymeric substrates, based on a huge spatio-temporal surface sampling acquired through atomic force microscopy. A \textit{pseudo}-steady state (where average surface roughness and spatial correlations stay constant in time) is observed at initial times, persisting up to deposition of $\sim 10^{4}$ monolayers. This state results from a fine balance between roughening and smoothening, as supported by a phenomenological growth model. KPZ statistics arises at long times, thoroughly verified by universal exponents, spatial covariance and several distributions. Recent theoretical generalizations of the Family-Vicsek scaling and the emergence of log-normal distributions during interface growth are experimentally confirmed. These results confirm that high vacuum vapor deposition of CdTe constitutes a genuine 2D-KPZ system, and expand our knowledge about possible substrate-induced short-time behaviors.Comment: 13 pages, 8 figures, 2 table

Temperature effect on (2+1) experimental Kardar-Parisi-Zhang growth

We report on the effect of substrate temperature (T) on both local structure and long-wavelength fluctuations of polycrystalline CdTe thin films deposited on Si(001). A strong T-dependent mound evolution is observed and explained in terms of the energy barrier to inter-grain diffusion at grain boundaries, as corroborated by Monte Carlo simulations. This leads to transitions from uncorrelated growth to a crossover from random-to-correlated growth and transient anomalous scaling as T increases. Due to these finite-time effects, we were not able to determine the universality class of the system through the critical exponents. Nevertheless, we demonstrate that this can be circumvented by analyzing height, roughness and maximal height distributions, which allow us to prove that CdTe grows asymptotically according to the Kardar-Parisi-Zhang (KPZ) equation in a broad range of T. More important, one finds positive (negative) velocity excess in the growth at low (high) T, indicating that it is possible to control the KPZ non-linearity by adjusting the temperature.Comment: 6 pages, 5 figure

Utilização de herbicidas no controle de plantas indesejáveis em pastagem natural.

A aplicação de herbicidas sob a pastagem natural, tanto para o estabelecimento de pastagens cultivadas através do plantio direto, como no controle de plantas indesejáveis tem crescido nos últimos anos. A pesquisa, até o presente momento não dispõe de informações seguras para recomendar tal procedimento. O efeito de herbicidas sobre uma vegetação natural tão diversificada e rica em espécies forrageiras tem sido uma das maiores interrogantes neste processo.bitstream/item/55664/1/ct24-1999.pd

A Numerical Approach to Coulomb Gauge QCD

We calculate the ghost two-point function in Coulomb gauge QCD with a simple model vacuum gluon wavefunction using Monte Carlo integration. This approach extends the previous analytic studies of the ghost propagator with this ansatz, where a ladder-rainbow expansion was unavoidable for calculating the path integral over gluon field configurations. The new approach allows us to study the possible critical behavior of the coupling constant, as well as the Coulomb potential derived from the ghost dressing function. We demonstrate that IR enhancement of the ghost correlator or Coulomb form factor fails to quantitatively reproduce confinement using Gaussian vacuum wavefunctional

Experimentally Witnessing the Quantumness of Correlations

The quantification of quantum correlations (other than entanglement) usually entails laboured numerical optimization procedures also demanding quantum state tomographic methods. Thus it is interesting to have a laboratory friendly witness for the nature of correlations. In this Letter we report a direct experimental implementation of such a witness in a room temperature nuclear magnetic resonance system. In our experiment the nature of correlations is revealed by performing only few local magnetization measurements. We also compare the witness results with those for the symmetric quantum discord and we obtained a fairly good agreement

Sincronização do estro de novilhas caprinas mestiças com PGF2a: dose e sub-dose em duas vias de aplicação.

Atualmente avalia-se a viabilidade de diferentes protocolos de sincronização do estro com PGF2a isolada, na redução de custos; buscando dose e via de aplicação eficazes, ampliando sua utilização na reprodução animal (FRAZÃO et al,2006). O emprego de sub-doses de PGF2a aplicadas intravulvarmente tem sido uma alternativa para reduzir custos. MGONGO (1988) verificou que, a redução nos níveis de progesterona sangüíneos, em cabras após aplicação de 125 mg de cloprostenol, via intramuscular, era semelhante àquela verificadas em fêmeas que receberam sub-dose (62,5 mg) por via submucosa vulvar. HEAP et al. (1985) demonstraram que a rapidez de difusão da PGF2a produzida no útero em direção aos ovários era devido, principalmente, aos sistemas linfático e sangüíneo locais, o que justifica a aplicação vulvar de drogas luteolíticas. O trabalho objetivou avaliar a eficiência da PGF2a na indução do estro constatada pela taxa de prenhez de novilhas caprinas após inseminação artificial utilizando duas doses de cloprostenol, aplicadas via intramuscular (IM) ou intramuscular vulvar (IMV)