18,961 research outputs found
Scaling in the crossover from random to correlated growth
In systems where deposition rates are high compared to diffusion, desorption
and other mechanisms that generate correlations, a crossover from random to
correlated growth of surface roughness is expected at a characteristic time
t_0. This crossover is analyzed in lattice models via scaling arguments, with
support from simulation results presented here and in other authors works. We
argue that the amplitudes of the saturation roughness and of the saturation
time scale as {t_0}^{1/2} and t_0, respectively. For models with lateral
aggregation, which typically are in the Kardar-Parisi-Zhang (KPZ) class, we
show that t_0 ~ 1/p, where p is the probability of the correlated aggregation
mechanism to take place. However, t_0 ~ 1/p^2 is obtained in solid-on-solid
models with single particle deposition attempts. This group includes models in
various universality classes, with numerical examples being provided in the
Edwards-Wilkinson (EW), KPZ and Villain-Lai-Das Sarma (nonlinear molecular-beam
epitaxy) classes. Most applications are for two-component models in which
random deposition, with probability 1-p, competes with a correlated aggregation
process with probability p. However, our approach can be extended to other
systems with the same crossover, such as the generalized restricted
solid-on-solid model with maximum height difference S, for large S. Moreover,
the scaling approach applies to all dimensions. In the particular case of
one-dimensional KPZ processes with this crossover, we show that t_0 ~ nu^{-1}
and nu ~ lambda^{2/3}, where nu and lambda are the coefficients of the linear
and nonlinear terms of the associated KPZ equations. The applicability of
previous results on models in the EW and KPZ classes is discussed.Comment: 14 pages + 5 figures, minor changes, version accepted in Phys. Rev.
Grão de bico e lentilha: duas novas hospedeiras de Sclerotium rolfsii no Planalto Central do Brasil.
Neste trabalho, relata-se, pela primeira vez, a ocorrência da murcha-de-esclerócio, causada por Sclerotium rolfsii em grão-de-bico (Cicer arietinum L.) e em lentilha (Lens culinaris Medikus) na Região do Planalto Central do Brasil.bitstream/item/85036/1/bpd-92.pd
Quantum Evolution of Inhomogeneities in Curved Space
We obtain the renormalized equations of motion for matter and semi-classical
gravity in an inhomogeneous space-time. We use the functional Schrodinger
picture and a simple Gaussian approximation to analyze the time evolution of
the model, and we establish the renormalizability of this
non-perturbative approximation. We also show that the energy-momentum tensor in
this approximation is finite once we consider the usual mass and coupling
constant renormalizations, without the need of further geometrical
counter-terms.Comment: 22 page
Extracellular matrix mimics using hyaluronan-based biomaterials
Hyaluronan (HA) is a critical element of the extracellular matrix (ECM). The regulated synthesis and degradation of HA modulates the ECM chemical and physical properties that, in turn, influence cellular behavior. HA triggers signaling pathways associated with the adhesion, proliferation, migration, and differentiation of cells, mediated by its interaction with specific cellular receptors or by tuning the mechanical properties of the ECM. This review summarizes the recent advances on strategies used to mimic the HA present in the ECM to study healthy or pathological cellular behavior. This includes the development of HA-based 2D and 3D in vitro tissue models for the seeding and encapsulation of cells, respectively, and HA particles as carriers for the targeted delivery of therapeutic agents.The authors acknowledge thefinancial support from the European Commission’s H2020 programme, under grantagreements H2020-WIDESPREAD-2014-668983-FORECAST, and H2020-MSCA-RISE-2019-872648-MEPHOS. S.A.acknowledges the Portuguese Foundation for Science and Technology (FCT) for her PhD grant (SFRH/BD/112075/2015)
Experimental determination of the non-extensive entropic parameter
We show how to extract the parameter from experimental data, considering
an inhomogeneous magnetic system composed by many Maxwell-Boltzmann homogeneous
parts, which after integration over the whole system recover the Tsallis
non-extensivity. Analyzing the cluster distribution of
LaSrMnO manganite, obtained through scanning tunnelling
spectroscopy, we measure the parameter and predict the bulk magnetization
with good accuracy. The connection between the Griffiths phase and
non-extensivity is also considered. We conclude that the entropic parameter
embodies information about the dynamics, the key role to describe complex
systems.Comment: Submitted to Phys. Rev. Let
Mancha-de-septória: doença limitante do tomateiro no perÃodo de chuvas.
bitstream/item/103062/1/cot-37.pd
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