5,627 research outputs found
Morphology of Fine-Particle Monolayers Deposited on Nanopatterned Substrates
We study the effect of the presence of a regular substrate pattern on the
irreversible adsorption of nanosized and colloid particles. Deposition of disks
of radius is considered, with the allowed regions for their center
attachment at the planar surface consisting of square cells arranged in a
square lattice pattern. We study the jammed state properties of a generalized
version of the random sequential adsorption model for different values of the
cell size, , and cell-cell separation, . The model shows a surprisingly
rich behavior in the space of the two dimensionless parameters
and . Extensive Monte Carlo simulations for system sizes of
square lattice unit cells were performed by utilizing an
efficient algorithm, to characterize the jammed state morphology.Comment: 11 pages, 10 figures, 3 table
Hall conductivity as bulk signature of topological transitions in superconductors
Topological superconductors may undergo transitions between phases with
different topological numbers which, like the case of topological insulators,
are related to the presence of gapless (Majorana) edge states. In
topological insulators the charge Hall conductivity is quantized, being
proportional to the number of gapless states running at the edge. In a
superconductor, however, charge is not conserved and, therefore,
is not quantized, even in the case of a topological
superconductor. Here it is shown that while the evolves
continuously between different topological phases of a topological
superconductor, its derivatives display sharp features signaling the
topological transitions. We consider in detail the case of a triplet
superconductor with p-wave symmetry in the presence of Rashba spin-orbit (SO)
coupling and externally applied Zeeman spin splitting. Generalization to the
cases where the pairing vector is not aligned with that of the SO coupling is
given. We generalize also to the cases where the normal system is already
topologically non-trivial.Comment: 10 pages, 10 figure
Random Sequential Adsorption: From Continuum to Lattice and Pre-Patterned Substrates
The random sequential adsorption (RSA) model has served as a paradigm for
diverse phenomena in physical chemistry, as well as in other areas such as
biology, ecology, and sociology. In the present work, we survey aspects of the
RSA model with emphasis on the approach to and properties of jammed states
obtained for large times in continuum deposition versus that on lattice
substrates, and on pre-patterned surfaces. The latter model has been of recent
interest in the context of efforts to use pre-patterning as a tool to improve
selfassembly in micro- and nanoscale surface structure engineering
Collaboration networks from a large CV database: dynamics, topology and bonus impact
Understanding the dynamics of research production and collaboration may
reveal better strategies for scientific careers, academic institutions and
funding agencies. Here we propose the use of a large and multidisciplinar
database of scientific curricula in Brazil, namely, the Lattes Platform, to
study patterns of scientific production and collaboration. In this database,
detailed information about publications and researchers are made available by
themselves so that coauthorship is unambiguous and individuals can be evaluated
by scientific productivity, geographical location and field of expertise. Our
results show that the collaboration network is growing exponentially for the
last three decades, with a distribution of number of collaborators per
researcher that approaches a power-law as the network gets older. Moreover,
both the distributions of number of collaborators and production per researcher
obey power-law behaviors, regardless of the geographical location or field,
suggesting that the same universal mechanism might be responsible for network
growth and productivity.We also show that the collaboration network under
investigation displays a typical assortative mixing behavior, where teeming
researchers (i.e., with high degree) tend to collaborate with others alike.
Finally, our analysis reveals that the distinctive collaboration profile of
researchers awarded with governmental scholarships suggests a strong bonus
impact on their productivity.Comment: 8 pages, 8 figure
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