A computationally efficient method for calculating the maximum conductance of disordered networks: Application to 1-dimensional conductors

Random networks of carbon nanotubes and metallic nanowires have shown to be very useful in the production of transparent, conducting films. The electronic transport on the film depends considerably on the network properties, and on the inter-wire coupling. Here we present a simple, computationally efficient method for the calculation of conductance on random nanostructured networks. The method is implemented on metallic nanowire networks, which are described within a single-orbital tight binding Hamiltonian, and the conductance is calculated with the Kubo formula. We show how the network conductance depends on the average number of connections per wire, and on the number of wires connected to the electrodes. We also show the effect of the inter-/intra-wire hopping ratio on the conductance through the network. Furthermore, we argue that this type of calculation is easily extendable to account for the upper conductivity of realistic films spanned by tunneling networks. When compared to experimental measurements, this quantity provides a clear indication of how much room is available for improving the film conductivity.Comment: 7 pages, 5 figure

The role of the equation of state and the space-time dimension in spherical collapse

We study the spherically symmetric collapse of a fluid with non-vanishing radial pressure in higher dimensional space-time. We obtain the general exact solution in the closed form for the equation of state ($P_r = \gamma \rho$) which leads to the explicit construction of the root equation governing the nature (black hole versus naked singularity) of the central singularity. A remarkable feature of the root equation is its invariance for the three cases: (${D+1}, {\gamma = -1}$), (${D}, {\gamma = 0}$) and (${D - 1}, {\gamma = 1}$) where $D$ is the dimension of space-time. That is, for the ultimate end result of the collapse, $D$-dimensional dust, ${D+1}$ - AdS (anti de Sitter)-like and ${D-1}$ - dS-like are absolutely equivalent.Comment: 4 Pages, RevTeX, no figures, minor changes, new references added, Detailed version to follo

Abstract specifications for concurrent maps (extended version)

Despite recent advances in reasoning about concurrent data structure libraries, the largest implementations in java.util.concurrent have yet to be verified. The key issue lies in the development of modular specifications, which provide clear logical boundaries between clients and implementations. A solution is to use recent advances in fine-grained concurrency reasoning, in particular the introduction of abstract atomicity to concurrent separation logic reasoning. We present two specifications of concurrent maps, both providing the clear boundaries we seek. We show that these specifications are equivalent, in that they can be built from each other. We show how we can verify client programs, such as a concurrent set and a producer-consumer client. We also give a substantial first proof that the main operations of ConcurrentSkipListMap in java.util.concurrent satisfy the map specification. This work demonstrates that we now have the technology to verify the largest implementations in java.util.concurrent

Multiplicação do porta-enxerto trifoliata por meio de estacas maduras.

bitstream/item/47090/1/comunicado-256.pd

Estruturação de sistema de LEDs em laboratório de cultura de tecidos.

bitstream/item/61630/1/Circular-121-J.pd

Tecnologia para produção de mudas orgânicas de citros.

bitstream/item/79723/1/comunicado-263.pd

Gravitational collapse of Type II fluid in higher dimensional space-times

We find the general solution of the Einstein equation for spherically symmetric collapse of Type II fluid (null strange quark fluid) in higher dimensions. It turns out that the nakedness and curvature strength of the shell focusing singularities carry over to higher dimensions. However, there is shrinkage of the initial data space for a naked singularity of the Vaidya collapse due to the presence of strange quark matter.Comment: RevTex4 style, 4 pages; Accepted in Phys. Rev.

Cultivares de laranjeira resistentes ao cangro citrico.

bitstream/CPACT-2009-09/12047/1/documento_249.pd