Biomedical subjects

I Balberg

Publications and source records attributed to I Balberg.

At least 19 recordsLinked to original sources

PubMed2006

Monte Carlo results for continuum percolation in low and high dimensions.

We report on Monte Carlo simulations of continuum percolation thresholds, by implementing highly efficient algorithms for very large samples. Our work, which includes percolation of hyperspheres, hypercubes, and boxes, in various dimensions, sizes, and shapes, has confirmed the expected dependence of the threshold on Vex, the total excluded volume, and on Bc, the average number of bonds per site. We have further confirmed that Vex=Bc, and that Bc is dependent on the objects shape, for which we offer a possible explanation. In particular we find that, counterintuitively, one can have Bc<1, as we have found for hyperspheres of dimension > or =12. From our many results for differently sized hyperspheres, we were also able to derive the correlation length exponent v solely from the behavior of the thresholds using finite-size scaling.

Journal Article↗

PubMed2006

Tunneling and nonuniversality in continuum percolation systems.

The values obtained experimentally for the conductivity critical exponent in numerous percolation systems, in which the interparticle conduction is by tunneling, were found to be in the range of t0 and about t0 + 10, where t0 is the universal conductivity exponent. These latter values are, however, considerably smaller than those predicted by the available "one-dimensional"-like theory of tunneling percolation. In this Letter, we show that this long-standing discrepancy can be resolved by considering the more realistic "three-dimensional" model and the limited proximity to the percolation threshold in all the many available experimental studies.

Journal Article↗

PubMed2005

Resonant coupling between surface vibrations and electronic states in silicon nanocrystals at the strong confinement regime.

A striking correlation between infrared photoinduced absorption spectra and the photoluminescence from silicon nanocrystals indicates that quantized electronic sublevels of the nanocrystals are resonantly coupled to surface vibrational modes via a polarization field produced by coherent longitudinal polar vibrations. Our experimental results and model support the assumption that the mechanism responsible for the efficient photoluminescence from silicon nanocrystals should be assigned to inhibition of nonradiative channels rather than enhancement of radiative channels.

Computer Simulation↗

PubMed2003

Electrical-thermal switching in carbon-black-polymer composites as a local effect.

Following the lack of microscopic information about the intriguing well-known electrical-thermal switching mechanism in carbon-black-polymer composites, we applied atomic force microscopy in order to reveal the local nature of the process and correlated it with the characteristics of the widely used commercial switches. We conclude that the switching events take place in critical interparticle tunneling junctions that carry most of the current. The macroscopic switched state is then a result of a dynamic-stationary state of fast switching and slow reconnection of the corresponding junctions.

Journal Article↗

PubMed1995