Optimizing the encounter rate in biological interactions: Lévy versus Brownian strategies

An important application involving two-species reaction-diffusion systems relates to the problem of finding the best statistical strategy for optimizing the encounter rate between organisms. We investigate the general problem of how the encounter rate depends on whether organisms move in Lévy or Brownian random walks. By simulating a limiting generalized searcher-target model (e.g., predator-prey, mating partner, pollinator-flower), we find that Lévy walks confer a significant advantage for increasing encounter rates when the searcher is larger or moves rapidly relative to the target, and when the target density is low.     

Rare earth cuprates as electrocatalysts for methanol oxidation

A series of rare earth cuprates with overall composition Ln_2−xM_xCu_1−yM_y′O_4−δ (where Ln=La and Nd; M=Sr, Ca and Ba; M′=Ru and Sb: 0.0≤x≤0.4 and y=0.1) have been tested as anode electrocatalysts for methanol oxidation. The evaluation of electrode kinetic parameters was made galvanostatically. The catalyst characterization was carried out by specific conductivity measurements, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and Iodometry. These materials exhibit significant activity for methanol oxidation at higher potentials. The linear correlation between Cu(3+) content and methanol oxidation activity suggests that the active sites for adsorption of methanol is Cu(3+). The methanol oxidation onset potential depends on the ease of Cu(2+)→Cu(3+) oxidation reaction. These materials show better tolerance towards the poisoning by the intermediates of methanol oxidation compared to that of conventional noble metal electrocatalysts (supported and bulk). The lattice oxygen in these oxides could be considered as active oxygen to remove CO intermediates of methanol oxidation reaction.     

Geometric properties of QCD string from Willmore functional

The extremum of the Willmore-like functional for m-dimensional Riemannian manifold immersed in d-dimensional Riemannian manifold under normal variations is studied and various cases of interest are examined. This study is used to relate the parameters of QCD string action, including the Polyakov–Kleinert extrinsic curvature action, with the geometric properties of the world sheet. The world sheet has been shown to have negative stiffness on the basis of the geometric considerations.     

In reference to a self-referential approach towards smooth multivariate approximation

Numerical Algorithms - Approximation of a multivariate function is an important theme in the field of numerical analysis and its applications, which continues to receive a constant attention. In...