5,491 research outputs found

    BIRDS AT AIRPORTS

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    Birds are a serious hazard to aviation. A bird or a flock of birds that suddenly rises from a runway or surrounding area may collide with incoming or departing aircraft and cause the aircraft to crash, possibly resulting in the loss of human life. Bird collision with aircraft is commonly known as “bird strike.” Damage caused to aircraft usually results from collision of one or more birds with the engines and/or fuselage. Although most bird strikes do not result in crashes, they do involve expensive structural and mechanical damage to aircraft. The incidence of this problem worldwide makes bird strike a serious economic problem

    Alien Registration- Godin, Leo C J. (Westbrook, Cumberland County)

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    https://digitalmaine.com/alien_docs/20051/thumbnail.jp

    Dynamic regulation of quaternary organization of the M1 muscarinic receptor by subtype-selective antagonist drugs

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    Although rhodopsin-like G protein-coupled receptors can exist as both monomers and non-covalently associated dimers/oligomers, the steady-state proportion of each form and whether this is regulated by receptor ligands is unknown. Herein we address these topics for the M1 muscarinic acetylcholine receptor, a key molecular target for novel cognition enhancers, by employing Spatial Intensity Distribution Analysis. This method can measure fluorescent particle concentration and assess oligomerization states of proteins within defined regions of living cells. Imaging and analysis of the basolateral surface of cells expressing some 50 molecules.microm-2 of the human muscarinic M1 receptor identified an ~75/25 mixture of receptor monomers and dimers/oligomers. Both sustained and shorter-term treatment with the selective M1 antagonist pirenzepine resulted in a large shift in the distribution of receptor species to favor the dimeric/oligomeric state. Although sustained treatment with pirenzepine also resulted in marked upregulation of the receptor, simple mass-action effects were not the basis for ligand-induced stabilization of receptor dimers/oligomers. The related antagonist telenzepine also produced stabilization and enrichment of the M1 receptor dimer population but the receptor subtype non-selective antagonists atropine and N-methylscopolamine did not. In contrast, neither pirenzepine nor telenzepine altered the quaternary organization of the related M3 muscarinic receptor. These data provide unique insights into the selective capacity of receptor ligands to promote and/or stabilize receptor dimers/oligomers and demonstrate that the dynamics of ligand regulation of the quaternary organization of G protein-coupled receptors is markedly more complex than previously appreciated. This may have major implications for receptor function and behavior

    Efficient Hole Trapping in Carbon Dot/Oxygen-Modified Carbon Nitride Heterojunction Photocatalysts for Enhanced Methanol Production from CO₂ under Neutral Conditions

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    Artificial photosynthesis of alcohols from CO 2 is a promising route to provide sustainable fuels. The performance is still unsatisfactory mainly due to the rapid charge relaxation compared to the sluggish photoreactions and the oxidation of alcohol products. Here, we demonstrate that CO 2 is reduced to methanol with 100% selectivity using water as the only electron donor on a carbon nitride-like polymer (FAT) decorated with carbon dots. The quantum efficiency of 5.9% (λ = 420 nm) is 300% higher than the previously reported carbon nitride junction. Using transient absorption spectroscopy, we observed that holes in FAT can be extracted by the carbon dots with nearly 75% efficiency before they become unreactive by trapping. Extraction of holes resulted in a greater density of photoelectrons, indicative of reduced recombination of shorter-lived reactive electrons. This work offers a unique strategy to promote photocatalysis by increasing the amount of reactive photogenerated charges via structure engineering and extraction before energy losses by deep trapping

    Solar H2_2 evolution in water with modified diketopyrrolopyrrole dyes immobilised on molecular Co and Ni catalyst–TiO2_2 hybrids

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    A series of diketopyrrolopyrrole (DPP) dyes with a terminal phosphonic acid group for attachment to metal oxide surfaces were synthesised and the effect of side chain modification on their properties investigated. The organic photosensitisers feature strong visible light absorption (λ\lambda = 400 to 575 nm) and electrochemical and fluorescence studies revealed that the excited state of all dyes provides sufficient driving force for electron injection into the TiO2_2 conduction band. The performance of the DPP chromophores attached to TiO2_2 nanoparticles for photocatalytic H2_2 evolution with co-immobilised molecular Co and Ni catalysts was subsequently studied, resulting in solar fuel generation with a dye-sensitised semiconductor nanoparticle system suspended in water without precious metal components. The performance of the DPP dyes in photocatalysis did not only depend on electronic parameters, but also on properties of the side chain such as polarity, steric hinderance and hydrophobicity as well as the specific experimental conditions and the nature of the sacrificial electron donor. In an aqueous pH 4.5 ascorbic acid solution with a phosphonated DuBois-type Ni catalyst, a DPP-based turnover number (TONDPP_{DPP}) of up to 205 was obtained during UV-free simulated solar light irradiation (100 mW cm2^{-2} , AM 1.5G, λ\lambda > 420 nm) after 1 day. DPP-sensitised TiO2_2 nanoparticles were also successfully used in combination with a hydrogenase or platinum instead of the synthetic H2_2 evolution catalysts and the platinum-based system achieved a TONDPP_{DPP} of up to 2660, which significantly outperforms an analogous system using a phosphonated Ru tris(bipyridine) dye (TONRu_{Ru} = 431). Finally, transient absorption spectroscopy was performed to study interfacial recombination and dye regeneration kinetics revealing that the different performances of the DPP dyes are most likely dictated by the different regeneration efficiencies of the oxidised chromophores.Support by the Christian Doppler Research Association (Austrian Federal Ministry of Science, Research and Economy and National Foundation for Research, Technology and Development), the OMV Group and the Ministry of Education (Singapore) is gratefully acknowledged. RG is grateful to FRQNT for a Postdoctoral Fellowship and JRD thanks the European Science Foundation project Intersolar (291482) for support

    An Incremental Learning Method to Support the Annotation of Workflows with Data-to-Data Relations

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    Workflow formalisations are often focused on the representation of a process with the primary objective to support execution. However, there are scenarios where what needs to be represented is the effect of the process on the data artefacts involved, for example when reasoning over the corresponding data policies. This can be achieved by annotating the workflow with the semantic relations that occur between these data artefacts. However, manually producing such annotations is difficult and time consuming. In this paper we introduce a method based on recommendations to support users in this task. Our approach is centred on an incremental rule association mining technique that allows to compensate the cold start problem due to the lack of a training set of annotated workflows. We discuss the implementation of a tool relying on this approach and how its application on an existing repository of workflows effectively enable the generation of such annotations

    The effects of parasitism and body length on positioning within wild fish shoals

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    The influence of body length and parasitism on the positioning behaviour of individuals in wild fish shoals was investigated by a novel means of capturing entire shoals of the banded killifish (Fundulus diaphanus, Lesueur) using a grid-net that maintained the two-dimensional positions of individuals within shoals. Fish in the front section of a shoal were larger than those in the rear. Individuals parasitized by the digenean trematode (Crassiphiala bulboglossa, Haitsma) showed a tendency to occupy the front of shoals. Parasitized fish were also found more in peripheral positions than central ones in a significant number of shoals. Shoal geometry was affected by the overall parasite prevalence of shoal members; shoals with high parasite prevalence displayed increasingly phallanx-like shoal formations, whereas shoals with low prevalence were more elliptical. There was no relationship between body length and parasite abundance or prevalence in the fish population which suggests body length and parasite status are independent predictors of positioning behaviour. Solitary individuals found outside shoals were both more likely to be parasitized and had higher parasite abundance than individuals engaged in shoaling. Differences in the shoaling behaviour of parasitized and unparasitized fish are discussed in the context of the adaptive manipulation hypothesis
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