92 research outputs found
Voltage-programmable liquid optical interface
Recently, there has been intense interest in photonic devices based on microfluidics, including displays and refractive tunable microlenses and optical beamsteerers, that work using the principle of electrowetting. Here, we report a novel approach to optical devices in which static wrinkles are produced at the surface of a thin film of oil as a result of dielectrophoretic forces. We have demonstrated this voltage-programmable surface wrinkling effect in periodic devices with pitch lengths of between 20 and 240 ”m and with response times of less than 40 ”s. By a careful choice of oils, it is possible to optimize either for high-amplitude sinusoidal wrinkles at micrometre-scale pitches or more complex non-sinusoidal profiles with higher Fourier components at longer pitches. This opens up the possibility of developing rapidly responsive voltage-programmable, polarization-insensitive transmission and reflection diffraction devices and arbitrary surface profile optical devices
Pharmacological Blockade of Serotonin 5-HT7 Receptor Reverses Working Memory Deficits in Rats by Normalizing Cortical Glutamate Neurotransmission
The role of 5-HT7 receptor has been demonstrated in various animal models of mood disorders; however its function in cognition remains largely speculative. This study evaluates the effects of SB-269970, a selective 5-HT7 antagonist, in a translational model of working memory deficit and investigates whether it modulates cortical glutamate and/or dopamine neurotransmission in rats. The effect of SB-269970 was evaluated in the delayed non-matching to position task alone or in combination with MK-801, a non-competitive NMDA receptor antagonist, and, in separate experiments, with scopolamine, a non-selective muscarinic antagonist. SB-269970 (10 mg/kg) significantly reversed the deficits induced by MK-801 (0.1 mg/kg) but augmented the deficit induced by scopolamine (0.06 mg/kg). The ability of SB-269970 to modulate MK-801-induced glutamate and dopamine extracellular levels was separately evaluated using biosensor technology and microdialysis in the prefrontal cortex of freely moving rats. SB-269970 normalized MK-801 -induced glutamate but not dopamine extracellular levels in the prefrontal cortex. Rat plasma and brain concentrations of MK-801 were not affected by co-administration of SB-269970, arguing for a pharmacodynamic rather than a pharmacokinetic mechanism. These results indicate that 5-HT7 receptor antagonists might reverse cognitive deficits associated with NMDA receptor hypofunction by selectively normalizing glutamatergic neurotransmission
PIF Genes Mediate the Effect of Sucrose on Seedling Growth Dynamics
As photoautotrophs, plants can use both the form and amount of fixed carbon as a
measure of the light environment. In this study, we used a variety of approaches
to elucidate the role of exogenous sucrose in modifying seedling growth
dynamics. In addition to its known effects on germination, high-resolution
temporal analysis revealed that sucrose could extend the number of days plants
exhibited rapid hypocotyl elongation, leading to dramatic increases in ultimate
seedling height. In addition, sucrose changed the timing of daily growth maxima,
demonstrating that diel growth dynamics are more plastic than previously
suspected. Sucrose-dependent growth promotion required function of multiple
phytochrome-interacting factors (PIFs), and overexpression of
PIF5 led to growth dynamics similar to plants exposed to
sucrose. Consistent with this result, sucrose was found to increase levels of
PIF5 protein. PIFs have well-established roles as integrators of response to
light levels, time of day and phytohormone signaling. Our findings strongly
suggest that carbon availability can modify the known photomorphogenetic
signaling network
15N/14N ratios of amino acids as a tool for studying terrestrial food webs: a case study of terrestrial insects (bees, wasps, and hornets)
Seabirds enhance coral reef productivity and functioning in the absence of invasive rats
Biotic connectivity between ecosystems can provide major transport of organic matter and nutrients, influencing ecosystem structure and productivity1, yet the implications are poorly understood owing to human disruptions of natural flows2. When abundant, seabirds feeding in the open ocean transport large quantities of nutrients onto islands, enhancing the productivity of island fauna and flora3,4. Whether leaching of these nutrients back into the sea influences the productivity, structure and functioning of adjacent coral reef ecosystems is not known. Here we address this question using a rare natural experiment in the Chagos Archipelago, in which some islands are rat-infested and others are rat-free. We found that seabird densities and nitrogen deposition rates are 760 and 251 times higher, respectively, on islands where humans have not introduced rats. Consequently, rat-free islands had substantially higher nitrogen stable isotope (ÎŽ15N) values in soils and shrubs, reflecting pelagic nutrient sources. These higher values of ÎŽ15N were also apparent in macroalgae, filter-feeding sponges, turf algae and fish on adjacent coral reefs. Herbivorous damselfish on reefs adjacent to the rat-free islands grew faster, and fish communities had higher biomass across trophic feeding groups, with 48% greater overall biomass. Rates of two critical ecosystem functions, grazing and bioerosion, were 3.2 and 3.8 times higher, respectively, adjacent to rat-free islands. Collectively, these results reveal how rat introductions disrupt nutrient flows among pelagic, island and coral reef ecosystems. Thus, rat eradication on oceanic islands should be a high conservation priority as it is likely to benefit terrestrial ecosystems and enhance coral reef productivity and functioning by restoring seabird-derived nutrient subsidies from large areas of ocean
Stable isotope compositions of bivalve shells and geochemistry of bulk sediments in a 5â20 ky fluvial section at KörösladĂĄny, SE Hungary: Sedimentary changes vs. climate signals
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