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

Lateral Gene Expression in Drosophila Early Embryos Is Supported by Grainyhead-Mediated Activation and Tiers of Dorsally-Localized Repression

The general consensus in the field is that limiting amounts of the transcription factor Dorsal establish dorsal boundaries of genes expressed along the dorsal-ventral (DV) axis of early Drosophila embryos, while repressors establish ventral boundaries. Yet recent studies have provided evidence that repressors act to specify the dorsal boundary of intermediate neuroblasts defective (ind), a gene expressed in a stripe along the DV axis in lateral regions of the embryo. Here we show that a short 12 base pair sequence (“the A-box”) present twice within the ind CRM is both necessary and sufficient to support transcriptional repression in dorsal regions of embryos. To identify binding factors, we conducted affinity chromatography using the A-box element and found a number of DNA-binding proteins and chromatin-associated factors using mass spectroscopy. Only Grainyhead (Grh), a CP2 transcription factor with a unique DNA-binding domain, was found to bind the A-box sequence. Our results suggest that Grh acts as an activator to support expression of ind, which was surprising as we identified this factor using an element that mediates dorsally-localized repression. Grh and Dorsal both contribute to ind transcriptional activation. However, another recent study found that the repressor Capicua (Cic) also binds to the A-box sequence. While Cic was not identified through our A-box affinity chromatography, utilization of the same site, the A-box, by both factors Grh (activator) and Cic (repressor) may also support a “switch-like” response that helps to sharpen the ind dorsal boundary. Furthermore, our results also demonstrate that TGF-β signaling acts to refine ind CRM expression in an A-box independent manner in dorsal-most regions, suggesting that tiers of repression act in dorsal regions of the embryo

Kinetic Phenomena in Thin Film Electronic Materials

Contains reports on twelve research projects.National Science Foundation (Grant ECS 85-06505)U.S. Air Force - Office of Scientific Research (Contract AFOSR-85-0154)Semiconductor Research Corporation (Contract 87-SP-080)National Science Foundation (Grant ECS 85-06565)International Business Machines, Inc.Sony International Business Machines, Inc.National Science Foundation (Grant DMR 84-18718)International Business Machines, Thomas J. Watson Research CenterJoint Services Electronics Program (Contract DAALO3-86-K-0002)National Science Foundation (Grant DMR 85-06030)Charles Stark Draper Laboratory (Contract DL-H-261827)Nippon Telegraph and Telephone, Inc

Microstructural Evolution in Thin Films of Electronic Materials

Contains reports on eight research projects.National Science Foundation (Grant ECS 85-06565)U.S. Air Force - Office of Scientific Research (Contract AFOSR 85-0154)National Science Foundation-Materials Research Laboratory(Grant DMR 81-19285)National Science Foundation (Grant DMR 85-06030)International Business Machines, Inc. Faculty Development AwardMitsui Career Development AwardInternational Business Machines, Inc.Semiconductor Research Corporation (Contract 86-05-080)Joint Services Electronics Program (Contract DAAG-29-83-K-0003)Charles Stark Draper LaboratoryDefense Advanced Research Projects Agency (DARPA)Nippon Telegraph and Telephone, Inc

Postoperative Complications in the Ahmed Baerveldt Comparison Study During Five Years of Follow-up

To compare the late complications in the Ahmed Baerveldt Comparison Study during 5 years of follow-up

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