The sound of waves in the Mutriku wave energy plant

Peer Reviewe

The significance of prey avoidance behaviour for the maintenance of a predator colour polymorphism

The existence of conspicuous colour polymorphisms in animals provides an ideal opportunity to examine the mechanisms which determine genetic and phenotypic variation in populations. It is well known that directional and negative frequency-dependent selection by predators can influence the persistence of colour polymorphisms in their prey, but much less attention has been paid to the idea that prey behaviour could generate selection on predator colour morphs. In this study, we examine the role that avoidance behaviour by honeybees might play in selection on a colour-polymorphic sit-and-wait predator, the crab spider Synema globosum. In two field experiments, we offered flowers harbouring spiders of different colour morphs to foraging honeybees. In the first, we tested for a pre-existing propensity in honeybees to avoid one spider morph over another, and whether this behaviour is influenced by the flower species on which spiders hunt. In the second, we tested the ability of bees to learn to avoid spider morphs associated with a previous simulated attack. Our results suggest that honeybees do not impose strong directional selection on spider morphs in our study population, and that avoidance behaviour is not influenced by flower species. However, we find evidence that honeybees learn to avoid spiders of a colour morph that has previously been associated with a simulated attack. These findings are the first empirical evidence for a mechanism by which prey behaviour might generate negative frequency-dependent selection on predator colour morphs, and hence potentially influence the long-term persistence of genetic and phenotypic diversity in predator populations

Electrode Materials, Thermal Annealing Sequences, and Lateral/Vertical Phase Separation of Polymer Solar Cells from Multiscale Molecular Simulations

The nanomorphologies of the bulk heterojunction (BHJ) layer of polymer solar cells are extremely sensitive to the electrode materials and thermal annealing conditions. In this work, the correlations of electrode materials, thermal annealing sequences, and resultant BHJ nanomorphological details of P3HT:PCBM BHJ polymer solar cell are studied by a series of large-scale, coarse-grained (CG) molecular simulations of system comprised of PEDOT:PSS/P3HT:PCBM/Al layers. Simulations are performed for various configurations of electrode materials as well as processing temperature. The complex CG molecular data are characterized using a novel extension of our graph-based framework to quantify morphology and establish a link between morphology and processing conditions. Our analysis indicates that vertical phase segregation of P3HT:PCBM blend strongly depends on the electrode material and thermal annealing schedule. A thin P3HT-rich film is formed on the top, regardless of bottom electrode material, when the BHJ layer is exposed to the free surface during thermal annealing. In addition, preferential segregation of P3HT chains and PCBM molecules toward PEDOT:PSS and Al electrodes, respectively, is observed. Detailed morphology analysis indicated that, surprisingly, vertical phase segregation does not affect the connectivity of donor/acceptor domains with respective electrodes. However, the formation of P3HT/PCBM depletion zones next to the P3HT/PCBM-rich zones can be a potential bottleneck for electron/hole transport due to increase in transport pathway length. Analysis in terms of fraction of intra- and interchain charge transports revealed that processing schedule affects the average vertical orientation of polymer chains, which may be crucial for enhanced charge transport, nongeminate recombination, and charge collection. The present study establishes a more detailed link between processing and morphology by combining multiscale molecular simulation framework with an extensive morphology feature analysis, providing a quantitative means for process optimization

The sound of waves in the Mutriku wave energy plant

Peer Reviewe

The sound of waves in the Mutriku wave energy plant

Peer Reviewe