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A standardized neighbor removal experiment was conducted in 12 plant communities located on three continents to test the null hypothesis that competition intensity (CI) was independent of the amount of plant biomass present. Six plots were chosen in each community to cover the range oflocal variation in plant biomass. In each plot the relative growth rate (RGR) of transplanted Poapratensis (Poaceae) seedlings was compared in the presence and absence of neighbors. Neighbors were removed experimentally using R. J. READER ET AL. Ecology, Vol. 75, No. 6 herbicide. Removing neighbors increased RGR of transplants significantly in most plots. CI increased with an increase in the amount of neighbor biomass present in one community where the range of neighbor biomass was greater than in any other community. In contrast, CI did not change significantly with an increase in neighbor biomass in other communities where the range of neighbor biomass was smaller. For the communities combined, CI was not related to neighbor biomass in a consistent fashion. These results indicate that competition may reduce growth over a wide range of habitat productivity, but the relationship between CI and neighbor biomass may differ among communities.

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Rendezvous is a fundamental operation for cognitive users to establish communication links. In [5], we proposed a jump-stay (JS) rendezvous algorithm which was shown to have the overall best performance. In this work, we propose an enhanced jump-stay (EJS) algorithm. Compared with JS, EJS lowers the upper-bounds of both the maximum timeto-rendezvous (MTTR) and the expected time-to-rendezvous (E(TTR)) from O(P 3 ) to O(P 2 ) under the asymmetric model, while keeping the same order O(P ) of upper-bounds of MTTR and E(TTR) under the symmetric mode, where P is the smallest prime number greater than the total number of channels.

We computationally study the micromechanics of shear-induced size segregation and propose distinct migration mechanisms for individual large and small particles. While small particles percolate through voids without enduring contacts, large particles climb under shear through their crowded neighborhoods with anisotropic contact network. Particle rotation associated with shear is necessary for the upward migration of large particles. Segregation of large particles can be suppressed with inadequate friction, or with no rotation; increasing interparticle friction promotes the migration of large particles, but has little effect on the percolation of small particles.

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Zebrafish larvae display rich locomotor behaviour upon external stimulation. The movement can be simultaneously tracked from many larvae arranged in multi-well plates. The resulting time-series locomotor data have been used to reveal new insights into neurobiology and pharmacology. However, the data are of large scale, and the corresponding locomotor behavior is affected by multiple factors. These issues pose a statistical challenge for comparing larval activities. To address this gap, this study has analyzed a visually-driven locomotor behaviour named the visual motor response (VMR) by the Hotelling’s T-squared test. This test is congruent with comparing locomotor profiles from a time period. Different wild-type (WT) strains were compared using the test, which shows that they responded differently to light change at different developmental stages. The performance of this test was evaluated by a power analysis, which shows that the test was sensitive for detecting differences between experimental groups with sample numbers that were commonly used in various studies. In addition, this study investigated the effects of various factors that might affect the VMR by multivariate analysis of variance (MANOVA). The results indicate that the larval activity was generally affected by stage, light stimulus, their interaction, and location in the plate. Nonetheless, different factors affected larval activity differently over time, as indicated by a dynamical analysis of the activity at each second. Intriguingly, this analysis also shows that biological and technical repeats had negligible effect on larval activity. This finding is consistent with that from the Hotelling’s T-squared test, and suggests that experimental repeats can be combined to enhance statistical power. Together, these investigations have established a statistical framework for analyzing VMR data, a framework that should be generally applicable to other locomotor data with similar structure.

SummaryComputational fluid dynamics and discrete element method (CFD–DEM) is extended with the volume of fluid (VOF) method to model free‐surface flows. The fluid is described on coarse CFD grids by solving locally averaged Navier–Stokes equations, and particles are modelled individually in DEM. Fluid–particle interactions are achieved by exchanging information between DEM and CFD. An advection equation is applied to solve the phase fraction of liquid, in the spirit of VOF, to capture the dynamics of free fluid surface. It also allows inter‐phase volume replacements between the fluid and solid particles. Further, as the size ratio (SR) of fluid cell to particle diameter is limited (i.e. no less than 4) in coarse‐grid CFD–DEM, a porous sphere method is adopted to permit a wider range of particle size without sacrificing the resolution of fluid grids. It makes use of more fluid cells to calculate local porosities. The developed solver (cfdemSolverVOF) is validated in different cases. A dam break case validates the CFD‐component and VOF‐component. Particle sedimentation tests validate the CFD–DEM interaction at various Reynolds numbers. Water‐level rising tests validate the volume exchange among phases. The porous sphere model is validated in both static and dynamic situations. Sensitivity analyses show that the SR can be reduced to 1 using the porous sphere approach, with the accuracy of analyses maintained. This allows more details of the fluid phase to be revealed in the analyses and enhances the applicability of the proposed model to geotechnical problems, where a highly dynamic fluid velocity and a wide range of particle sizes are encountered. Copyright © 2015 John Wiley & Sons, Ltd.