9,428 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
Recent advances and open challenges in percolation
Percolation is the paradigm for random connectivity and has been one of the
most applied statistical models. With simple geometrical rules a transition is
obtained which is related to magnetic models. This transition is, in all
dimensions, one of the most robust continuous transitions known. We present a
very brief overview of more than 60 years of work in this area and discuss
several open questions for a variety of models, including classical, explosive,
invasion, bootstrap, and correlated percolation
Theory of Andreev reflection in a two-orbital model of iron-pnictide superconductors
A recently developed theory for the problem of Andreev reflection between a
normal metal (N) and a multiband superconductor (MBS) assumes that the incident
wave from the normal metal is coherently transmitted through several bands
inside the superconductor. Such splitting of the probability amplitude into
several channels is the analogue of a quantum waveguide. Thus, the appropriate
matching conditions for the wave function at the N/MBS interface are derived
from an extension of quantum waveguide theory. Interference effects between the
transmitted waves inside the superconductor manifest themselves in the
conductance. We provide results for a FeAs superconductor, in the framework of
a recently proposed effective two-band model and two recently proposed gap
symmetries: in the sign-reversed s-wave () scenario
resonant transmission through surface Andreev bound states (ABS) at nonzero
energy is found as well as destructive interference effects that produce zeros
in the conductance; in the extended s-wave ()
scenario no ABS at finite energy are found.Comment: 4 pages, 5 figure
Historical Roots of Histrionic Personality Disorder
Histrionic Personality Disorder is one of the most ambiguous diagnostic categories in psychiatry. Hysteria is a classical term that includes a wide variety of psychopathological states. Ancient Egyptians and Greeks blamed a displaced womb, for many women's afflictions. Several researchers from the 18th and 19th centuries studied this theme, namely, Charcot who defined hysteria as a "neurosis" with an organic basis and Sigmund Freud who redefined "neurosis" as a re-experience of past psychological trauma. Histrionic personality disorder (HPD) made its first official appearance in the Diagnostic and Statistical Manual of Mental Disorders II (DSM-II) and since the DSM-III, HPD is the only disorder that kept the term derived from the old concept of hysteria. The subject of hysteria has reflected positions about health, religion and relationships between the sexes in the last 4000 years, and the discussion is likely to continue
Enhancement of the critical temperature in iron-pnictide superconductors by finite size effects
Recent experiments have shown that, in agreement with previous theoretical
predictions, superconductivity in metallic nanostructures can be enhanced with
respect to the bulk limit. Motivated by these results we study finite size
effects (FSE) in an iron-pnictide superconductor. For realistic values of the
bulk critical temperature Tc ~ 20-50K, we find that, in the nanoscale region L
~ 10 nm, Tc(L) has a complicated oscillating pattern as a function of the
system size L. A substantial enhancement of Tc with respect to the bulk limit
is observed for different boundary conditions, geometries and two microscopic
models of superconductivity. Thermal fluctuations, which break long range
order, are still small in this region. Finally we show that the differential
conductance, an experimental observable, is also very sensitive to FSE.Comment: 4 pages, 3 figure
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