RESUMO
We study the surface roughness of prototype models displaying self-organized criticality (SOC) and their noncritical variants in one dimension. For SOC systems, we find that two seemingly equivalent definitions of surface roughness yield different asymptotic scaling exponents. Using approximate analytical arguments and extensive numerical studies we conclude that this ambiguity is due to the special scaling properties of the nonlinear steady state surface. We also find that there is no such ambiguity for non-SOC models, although there may be intermediate crossovers to different roughness values. Such crossovers need to be distinguished from the true asymptotic behavior, as in the case of a noncritical disordered sandpile model studied by Barker and Mehta [Phys. Rev. E 61, 6765 (2000)].
RESUMO
It has recently been proposed that fluctuating "pulled" fronts propagating into an unstable state should not be in the standard Kardar-Parisi-Zhang (KPZ) universality class for rough interface growth. We introduce an effective field equation for this class of problems, and show on the basis of it that noisy pulled fronts in d+1 bulk dimensions should be in the universality class of the ((d+1)+1)D KPZ equation rather than of the (d+1)D KPZ equation. Our scenario ties together a number of heretofore unexplained observations in the literature, and is supported by previous numerical results.
RESUMO
We argue that while fluctuating fronts propagating into an unstable state should be in the standard Kardar-Parisi-Zhang (KPZ) universality class when they are pushed, they should not when they are pulled: The 1/t velocity relaxation of deterministic pulled fronts makes it unlikely that the KPZ equation is their proper effective long-wavelength low-frequency theory. Simulations in 2D confirm the proposed scenario, and yield exponents beta approximately 0.29+/-0.01, zeta approximately 0.40+/-0.02 for fluctuating pulled fronts, instead of the (1+1)D KPZ values beta = 1/3, zeta = 1/2. Our value of beta is consistent with an earlier result of Riordan et al., and with a recent conjecture that the exponents are the (2+1)D KPZ values.
RESUMO
In the present study 1123 Naval personnel posted in one of the Naval bases were interviewed to find out the existing level of knowledge regarding AIDS and its prevention. The personnel had reasonably fair idea about the disease, modes of transmission and its prevention. It was interesting to observe that personnel had information about heterosexual transmission of disease and it is relevant in our context as in India and other Asian countries, the main transmission is through heterosexual route. About 19.31% of sailors as compared to 2.44% of officers had misconception that the disease is curable. The role of refresher health education efforts for imparting factual up-to-date information to the Naval community has been brought out.
