13,843 research outputs found
On the origins of scaling corrections in ballistic growth models
We study the ballistic deposition and the grain deposition models on
two-dimensional substrates. Using the Kardar-Parisi-Zhang (KPZ) ansatz for
height fluctuations, we show that the main contribution to the intrinsic width,
which causes strong corrections to the scaling, comes from the fluctuations in
the height increments along deposition events. Accounting for this correction
in the scaling analysis, we obtained scaling exponents in excellent agreement
with the KPZ class. We also propose a method to suppress these corrections,
which consists in divide the surface in bins of size and use only
the maximal height inside each bin to do the statistics. Again, scaling
exponents in remarkable agreement with the KPZ class were found. The binning
method allowed the accurate determination of the height distributions of the
ballistic models in both growth and steady state regimes, providing the
universal underlying fluctuations foreseen for KPZ class in 2+1 dimensions. Our
results provide complete and conclusive evidences that the ballistic model
belongs to the KPZ universality class in dimensions. Potential
applications of the methods developed here, in both numerics and experiments,
are discussed.Comment: 8 pages, 7 figure
Flavour changing strong interaction effects on top quark physics at the LHC
We perform a model independent analysis of the flavour changing strong
interaction vertices relevant to the LHC. In particular, the contribution of
dimension six operators to single top production in various production
processes is discussed, together with possible hints for identifying signals
and setting bounds on physics beyond the standard model.Comment: Authors corrections (references added
Initial pseudo-steady state & asymptotic KPZ universality in semiconductor on polymer deposition
The Kardar-Parisi-Zhang (KPZ) class is a paradigmatic example of universality
in nonequilibrium phenomena, but clear experimental evidences of asymptotic
2D-KPZ statistics are still very rare, and far less understanding stems from
its short-time behavior. We tackle such issues by analyzing surface
fluctuations of CdTe films deposited on polymeric substrates, based on a huge
spatio-temporal surface sampling acquired through atomic force microscopy. A
\textit{pseudo}-steady state (where average surface roughness and spatial
correlations stay constant in time) is observed at initial times, persisting up
to deposition of monolayers. This state results from a fine
balance between roughening and smoothening, as supported by a phenomenological
growth model. KPZ statistics arises at long times, thoroughly verified by
universal exponents, spatial covariance and several distributions. Recent
theoretical generalizations of the Family-Vicsek scaling and the emergence of
log-normal distributions during interface growth are experimentally confirmed.
These results confirm that high vacuum vapor deposition of CdTe constitutes a
genuine 2D-KPZ system, and expand our knowledge about possible
substrate-induced short-time behaviors.Comment: 13 pages, 8 figures, 2 table
Memory in the Black-Scholes model
The evolution in time of European options is usually studied using
the Black-Scholes formula. This formula is obtained from the equivalence between
the Black-Scholes equation and a heat equation. The solution of the last equation
presents infinite speed of propagation which induces the same property for European
options. In this paper we study integro-differential equations which can be used to
describe the evolution of European options and which is established replacing the
heat equation by a delayed heat equation.Center for Mathematics of University of Coimbra; Project PTDC/MAT/74548/200
Temperature effect on (2+1) experimental Kardar-Parisi-Zhang growth
We report on the effect of substrate temperature (T) on both local structure
and long-wavelength fluctuations of polycrystalline CdTe thin films deposited
on Si(001). A strong T-dependent mound evolution is observed and explained in
terms of the energy barrier to inter-grain diffusion at grain boundaries, as
corroborated by Monte Carlo simulations. This leads to transitions from
uncorrelated growth to a crossover from random-to-correlated growth and
transient anomalous scaling as T increases. Due to these finite-time effects,
we were not able to determine the universality class of the system through the
critical exponents. Nevertheless, we demonstrate that this can be circumvented
by analyzing height, roughness and maximal height distributions, which allow us
to prove that CdTe grows asymptotically according to the Kardar-Parisi-Zhang
(KPZ) equation in a broad range of T. More important, one finds positive
(negative) velocity excess in the growth at low (high) T, indicating that it is
possible to control the KPZ non-linearity by adjusting the temperature.Comment: 6 pages, 5 figure
The Usage of Data Augmentation Strategies on the Detection of Murmur Waves in a Pcg Signal
Cardiac auscultation is a key screening tool used for cardiovascular evaluation. When used properly, it speeds up treatment and thus improving the patient’s life quality. However, the analysis and interpretation of the heart sound signals is subjective and dependent of the physician’s experience and domain knowledge. A computer assistant decision (CAD) system that automatically analyse heart sound signals, can not only support physicians in their clinical decisions but also release human resources to other tasks. In this paper, and to the best of our knowledge, for the first time a SMOTE strategy is used to boost a Convolutional Neural Network performance on the detection of murmur waves. Using the SMOTE strategy, a CNN achieved an overall of 88.43%.info:eu-repo/semantics/publishedVersio
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