Infection fronts in randomly varying transmission-rate media.

We numerically investigate the geometry and transport properties of infection fronts within the spatial SIR model in two dimensions. The model incorporates short-range correlated quenched random transmission rates. Our findings reveal that the critical average transmission rate for the steady-state propagation of the infection is overestimated by the naive mean-field homogenization.

Do chromium-resistant bacterial symbionts of hyperaccumulator Callitriche cophocarpa support their host in phytobial remediation of water?

Callitriche cophocarpa Sendtn. is a macrophyte widely distributed in aquatic systems of the temperate climate zone and a known hyperaccumulator of chromium. Ten pure symbiotic bacterial isolates of C.

In Vivo Ca3 Channel Inhibition Promotes Maturation of Glucose-Dependent Ca Signaling in Human iPSC-Islets.

Ca3 channels are ontogenetically downregulated with the maturation of certain electrically excitable cells, including pancreatic β cells. Abnormally exaggerated Ca3 channels drive the dedifferentiation of mature β cells. This led us to question whether excessive Ca3 channels, retained mistakenly in engineered human-induced pluripotent stem cell-derived islet (hiPSC-islet) cells, act as an obstacle to hiPSC-islet maturation.

Reproductive Biology of Dry Grassland Specialist L. and Its Implications for Conservation.

, a component of xerothermic grasslands, is a declining species and deserves active conservation treatments in many countries preceded by studies on the biology of its reproduction. So far, our knowledge of , a species with two modes of reproduction, has been fragmentary. The purpose of the studies presented here was to describe the annual development cycle of with particular emphasis on the production of underground tuber clusters that serve as vegetative propagation.

Intracameral Microimaging of Maturation of Human iPSC Derivatives into Islet Endocrine Cells.

We exploited the anterior chamber of the eye (ACE) of immunodeficient mice as an ectopic site for both transplantation and microimaging of engineered surrogate islets from human induced pluripotent stem cells (hiPSC-SIs). These islets contained a majority of insulin-expressing cells, positive or negative for PDX1 and NKX6.1, and a minority of glucagon- or somatostatin-positive cells.

The Effectiveness of the Sexual Reproduction in Selected Clonal and Nonclonal Species of the Genus .

Generative processes have been evaluated in six European buttercup species in order to verify the hypothesis that the reproduction efficiency of clonal species is lower than that of nonclonal ones. The study covered common species (, , , , ) and the endangered . The following properties have been assessed: pollen viability (staining method), pollen grain germination and the pollen-tube elongation in pistil tissues (fluorescence microscopy), seed formation efficiency, seed viability (tetrazolium test) and germination ability by introducing factors interrupting dormancy (low temperature and gibberellin application).

Response of physiological parameters in Dionaea muscipula J. Ellis teratomas transformed with rolB oncogene.

Background: Plant transformation with rol oncogenes derived from wild strains of Rhizobium rhizogenes is a popular biotechnology tool. Transformation effects depend on the type of rol gene, expression level, and the number of gene copies incorporated into the plant's genomic DNA. Although rol oncogenes are known as inducers of plant secondary metabolism, little is known about the physiological response of plants subjected to transformation.

Thermally rounded depinning of an elastic interface on a washboard potential.

The thermal rounding of the depinning transition of an elastic interface sliding on a washboard potential is studied through analytic arguments and very accurate numerical simulations. We confirm the standard view that well below the depinning threshold the average velocity can be calculated considering thermally activated nucleation of defects. However, we find that the straightforward extension of this analysis to near or above the depinning threshold does not fully describe the physics of the thermally assisted motion.

Non-Gaussian tail in the force distribution: a hallmark of correlated disorder in the host media of elastic objects.

Inferring the nature of disorder in the media where elastic objects are nucleated is of crucial importance for many applications but remains a challenging basic-science problem. Here we propose a method to discern whether weak-point or strong-correlated disorder dominates based on characterizing the distribution of the interaction forces between objects mapped in large fields-of-view. We illustrate our proposal with the case-study system of vortex structures nucleated in type-II superconductors with different pinning landscapes.

Hysteretic depinning of a particle in a periodic potential: Phase diagram and criticality.

We consider a massive particle driven with a constant force in a periodic potential and subjected to a dissipative friction. As a function of the drive and damping, the phase diagram of this paradigmatic model is well known to present a pinned, a sliding, and a bistable regime separated by three distinct bifurcation lines. In physical terms, the average velocity v of the particle is nonzero only if either (i) the driving force is large enough to remove any stable point, forcing the particle to slide or (ii) there are local minima but the damping is small enough, below a critical damping, for the inertia to allow the particle to cross barriers and follow a limit cycle; this regime is bistable and whether v>0 or v=0 depends on the initial state.

Roughening of the anharmonic Larkin model.

We study the roughening of d-dimensional directed elastic interfaces subject to quenched random forces. As in the Larkin model, random forces are considered constant in the displacement direction and uncorrelated in the perpendicular direction. The elastic energy density contains an harmonic part, proportional to (∂_{x}u)^{2}, and an anharmonic part, proportional to (∂_{x}u)^{2n}, where u is the displacement field and n>1 an integer.

Magnetic domain wall creep and depinning: A scalar field model approach.

Magnetic domain wall motion is at the heart of new magnetoelectronic technologies and hence the need for a deeper understanding of domain wall dynamics in magnetic systems. In this context, numerical simulations using simple models can capture the main ingredients responsible for the complex observed domain wall behavior. We present a scalar field model for the magnetization dynamics of quasi-two-dimensional systems with a perpendicular easy axis of magnetization which allows a direct comparison with typical experimental protocols, used in polar magneto-optical Kerr effect microscopy experiments.

Statistics of zero crossings in rough interfaces with fractional elasticity.

We study numerically the distribution of zero crossings in one-dimensional elastic interfaces described by an overdamped Langevin dynamics with periodic boundary conditions. We model the elastic forces with a Riesz-Feller fractional Laplacian of order z=1+2ζ, such that the interfaces spontaneously relax, with a dynamical exponent z, to a self-affine geometry with roughness exponent ζ. By continuously increasing from ζ=-1/2 (macroscopically flat interface described by independent Ornstein-Uhlenbeck processes [Phys.

Localization of soft modes at the depinning transition.

We characterize the soft modes of the dynamical matrix at the depinning transition, and compare the matrix with the properties of the Anderson model (and long-range generalizations). The density of states at the edge of the spectrum displays a universal linear tail, different from the Lifshitz tails. The eigenvectors are instead very similar in the two matrix ensembles.

Creep and thermal rounding close to the elastic depinning threshold.

We study the slow stochastic dynamics near the depinning threshold of an elastic interface in a random medium by solving a particularly suited model of hopping interacting particles that belongs to the quenched-Edwards-Wilkinson depinning universality class. The model allows us to compare the cases of uniformly activated and Arrhenius activated hops. In the former case, the velocity accurately follows a standard scaling law of the force and noise intensity with the analog of the thermal rounding exponent satisfying a modified "hyperscaling" relation.

Methylation of protein phosphatase 2A-Influence of regulators and environmental stress factors.

Protein phosphatase 2A catalytic subunit (PP2A-C) has a terminal leucine subjected to methylation, a regulatory mechanism conserved from yeast to mammals and plants. Two enzymes, LCMT1 and PME1, methylate and demethylate PP2A-C, respectively. The physiological importance of these posttranslational modifications is still enigmatic.

Spatiotemporal Patterns in Ultraslow Domain Wall Creep Dynamics.

In the presence of impurities, ferromagnetic and ferroelectric domain walls slide only above a finite external field. Close to this depinning threshold, they proceed by large and abrupt jumps called avalanches, while, at much smaller fields, these interfaces creep by thermal activation. In this Letter, we develop a novel numerical technique that captures the ultraslow creep regime over huge time scales.

Universal Pinning Energy Barrier for Driven Domain Walls in Thin Ferromagnetic Films.

We report a comparative study of magnetic field driven domain wall motion in thin films made of different magnetic materials for a wide range of field and temperature. The full thermally activated creep motion, observed below the depinning threshold, is shown to be described by a unique universal energy barrier function. Our findings should be relevant for other systems whose dynamics can be modeled by elastic interfaces moving on disordered energy landscapes.

Distribution of zeros in the rough geometry of fluctuating interfaces.

We study numerically the correlations and the distribution of intervals between successive zeros in the fluctuating geometry of stochastic interfaces, described by the Edwards-Wilkinson equation. For equilibrium states we find that the distribution of interval lengths satisfies a truncated Sparre-Andersen theorem. We show that boundary-dependent finite-size effects induce nontrivial correlations, implying that the independent interval property is not exactly satisfied in finite systems.

Accumulation patterns of Cr in Callitriche organs--qualitative and quantitative analysis.

The aims of this study were both the qualitative and quantitative analysis of chromium accumulation in the shoots of Callitriche cophocarpa. This globally distributed, submersed macrophyte exhibits outstanding Cr phytoremediation capacity in an aquatic environment. Cr was applied separately for 7 days at two stable forms as Cr(VI) and Cr(III), known from their diverse physicochemical properties and toxicities.

Pinning-dependent field-driven domain wall dynamics and thermal scaling in an ultrathin Pt/Co/Pt magnetic film.

Magnetic-field-driven domain wall motion in an ultrathin Pt/Co(0.45  nm)/Pt ferromagnetic film with perpendicular anisotropy is studied over a wide temperature range. Three different pinning dependent dynamical regimes are clearly identified: the creep, the thermally assisted flux flow, and the depinning, as well as their corresponding crossovers.

Infinite family of second-law-like inequalities.

The probability distribution function for an out of equilibrium system may sometimes be approximated by a physically motivated "trial" distribution. A particularly interesting case is when a driven system (e.g.

Thermal rounding exponent of the depinning transition of an elastic string in a random medium.

We study numerically thermal effects at the depinning transition of an elastic string driven in a two-dimensional uncorrelated disorder potential. The velocity of the string exactly at the sample critical force is shown to behave as V~T(ψ), with ψ the thermal rounding exponent. We show that the computed value of the thermal rounding exponent, ψ=0.

Maximum relative height of elastic interfaces in random media.

The distribution of the maximal relative height (MRH) of self-affine one-dimensional elastic interfaces in a random potential is studied. We analyze the ground-state configuration at zero driving force, and the critical configuration exactly at the depinning threshold, both for the random-manifold and random-periodic universality classes. These configurations are sampled by exact numerical methods, and their MRH distributions are compared with those with the same roughness exponent and boundary conditions, but produced by independent Fourier modes with normally distributed amplitudes.