1,209 research outputs found

    A target enrichment method for gathering phylogenetic information from hundreds of loci: An example from the Compositae.

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    UnlabelledPremise of the studyThe Compositae (Asteraceae) are a large and diverse family of plants, and the most comprehensive phylogeny to date is a meta-tree based on 10 chloroplast loci that has several major unresolved nodes. We describe the development of an approach that enables the rapid sequencing of large numbers of orthologous nuclear loci to facilitate efficient phylogenomic analyses. •Methods and resultsWe designed a set of sequence capture probes that target conserved orthologous sequences in the Compositae. We also developed a bioinformatic and phylogenetic workflow for processing and analyzing the resulting data. Application of our approach to 15 species from across the Compositae resulted in the production of phylogenetically informative sequence data from 763 loci and the successful reconstruction of known phylogenetic relationships across the family. •ConclusionsThese methods should be of great use to members of the broader Compositae community, and the general approach should also be of use to researchers studying other families

    Propulsion Study for Small Transport Aircraft Technology (STAT)

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    Propulsion requirements were determined for 0.5 and 0.7 Mach aircraft. Sensitivity studies were conducted on both these aircraft to determine parametrically the influence of propulsion characteristics on aircraft size and direct operating cost (DOC). Candidate technology elements and design features were identified and parametric studies conducted to select the STAT advanced engine cycle. Trade off studies were conducted to determine those advanced technologies and design features that would offer a reduction in DOC for operation of the STAT engines. These features were incorporated in the two STAT engines. A benefit assessment was conducted comparing the STAT engines to current technology engines of the same power and to 1985 derivatives of the current technology engines. Research and development programs were recommended as part of an overall technology development plan to ensure that full commercial development of the STAT engines could be initiated in 1988

    Temperature dependence of the triplet diffusion and quenching rates in films of an Ir(ppy)(3)-cored dendrimer

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    We study photoluminescence and triplet-triplet exciton annihilation in a neat film of a fac-tris(2-phenylpyridyl)iridium(III) [Ir(ppy)(3)]-cored dendrimer and in its blend with a 4,4(')-bis(N-carbazolyl)biphenyl host for the temperature range of 77-300 K. The nearest neighbor hopping rate of triplet excitons is found to increase by a factor of 2 with temperature between 150 and 300 K and is temperature independent at lower temperature. The intermolecular quenching rate follows the Arrhenius law with an activation energy of 7 meV, which can be explained by stronger dipole-dipole interactions with the donor molecule in the higher triplet substate. The results indicate that energy disorder has no significant effect on triplet transport and quenching in these materials

    Hilbert-Post completeness for the state and the exception effects

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    In this paper, we present a novel framework for studying the syntactic completeness of computational effects and we apply it to the exception effect. When applied to the states effect, our framework can be seen as a generalization of Pretnar's work on this subject. We first introduce a relative notion of Hilbert-Post completeness, well-suited to the composition of effects. Then we prove that the exception effect is relatively Hilbert-Post complete, as well as the "core" language which may be used for implementing it; these proofs have been formalized and checked with the proof assistant Coq.Comment: Siegfried Rump (Hamburg University of Technology), Chee Yap (Courant Institute, NYU). Sixth International Conference on Mathematical Aspects of Computer and Information Sciences , Nov 2015, Berlin, Germany. 2015, LNC

    On coalgebras with internal moves

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    In the first part of the paper we recall the coalgebraic approach to handling the so-called invisible transitions that appear in different state-based systems semantics. We claim that these transitions are always part of the unit of a certain monad. Hence, coalgebras with internal moves are exactly coalgebras over a monadic type. The rest of the paper is devoted to supporting our claim by studying two important behavioural equivalences for state-based systems with internal moves, namely: weak bisimulation and trace semantics. We continue our research on weak bisimulations for coalgebras over order enriched monads. The key notions used in this paper and proposed by us in our previous work are the notions of an order saturation monad and a saturator. A saturator operator can be intuitively understood as a reflexive, transitive closure operator. There are two approaches towards defining saturators for coalgebras with internal moves. Here, we give necessary conditions for them to yield the same notion of weak bisimulation. Finally, we propose a definition of trace semantics for coalgebras with silent moves via a uniform fixed point operator. We compare strong and weak bisimilation together with trace semantics for coalgebras with internal steps.Comment: Article: 23 pages, Appendix: 3 page

    Triplet exciton diffusion and phosphorescence quenching in Iridium(III)-Centered dendrimers

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    A study of triplet-triplet exciton annihilation and nonradiative decay in films of iridium(III)-centered phosphorescent dendrimers is reported. The average separation of the chromophore was tuned by the molecular structure and also by blending with a host material. It was found that triplet exciton hopping is controlled by electron exchange interactions and can be over 600 times faster than phosphorescence quenching. Nonradiative decay occurs by weak dipole-dipole interactions and is independent of exciton diffusion, except in very thin films

    Computational fluid dynamics modelling of an entire synchronous generator for improved thermal management

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    This study is the first in a series dedicated to investigating the airflow and thermal management of electrical machines. Owing to the temperature dependent resistive losses in the machine's windings, any improvement in cooling provides a direct reduction in losses and an increase in efficiency. This study focuses on the airflow which is intrinsically linked to the thermal behaviour of the machine as well as the windage power consumed to drive the air through the machine. A full computational fluid dynamics (CFD) model has been used to analyse the airflow around all major components of the machine. Results have been experimentally validated and investigated. At synchronous speed the experimentally tested mass flow rate and windage torque were under predicted by 4% and 7%, respectively, by the CFD. A break-down of torque by component shows that the fan consumes approximately 87% of the windage torque

    Design exploration addressing the intrinsic relationship between individuals and the living environment

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    Thesis (M. Arch)--Massachusetts Institute of Technology, Dept. of Architecture, 1984.MICROFICHE COPY AVAILABLE IN ARCHIVES AND ROTCH.Includes bibliographical references (leaves 138-142).The architecture of public housing is generally lacking. It reflects a deteriorated national image of low-income housing and holds far-reaching consequences for the poor who have their own image of public housing. This thesis is an architectural investigation, and because it deals with images -- what people see and feel -- the sociological influences are strong as well. The concern of this thesis is creating positive images of public housing from both the residents' and the public's perspectives. To do so, it points out specific architectural devices which promote an improved image and better quality homes. The relationship between the individual and the living environment is critical to the process which yields the final design. An examination of the meaning of the house defines the parameters of this relationship as it initiates a user-oriented design theme. The result demonstrates that a process deeply rooted this way and based on step-by-step design decisions, ultimately satisfies user needs without soliciting the usual stigma public housing carries.by Joann Stephanie Staton.M.Arc

    Nicotinic acetylcholine receptors modulate osteoclastogenesis

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    Background: Our aim was to investigate the role of nicotinic acetylcholine receptors (nAChRs) in in-vitro osteoclastogenesis and in in-vivo bone homeostasis. Methods: The presence of nAChR subunits as well as the in-vitro effects of nAChR agonists were investigated by ex vivo osteoclastogenesis assays, real-time polymerase chain reaction, Western blot and flow cytometry in murine bone marrow-derived macrophages differentiated in the presence of recombinant receptor activator of nuclear factor kappa B ligand (RANKL) and macrophage colony-stimulating factor (M-CSF). The bone phenotype of mice lacking various nAChR subunits was investigated by peripheral quantitative computed tomography and histomorphometric analysis. Oscillations in the intracellular calcium concentration were detected by measuring the Fura-2 fluorescence intensity. Results: We could demonstrate the presence of several nAChR subunits in bone marrow-derived macrophages stimulated with RANKL and M-CSF, and showed that they are capable of producing acetylcholine. nAChR ligands reduced the number of osteoclasts as well as the number of tartrate-resistant acidic phosphatase-positive mononuclear cells in a dose-dependent manner. In vitro RANKL-mediated osteoclastogenesis was reduced in mice lacking α7 homomeric nAChR or β2-containing heteromeric nAChRs, while bone histomorphometry revealed increased bone volume as well as impaired osteoclastogenesis in male mice lacking the α7 nAChR. nAChR ligands inhibited RANKL-induced calcium oscillation, a well-established phenomenon of osteoclastogenesis. This inhibitory effect on Ca2+ oscillation subsequently led to the inhibition of RANKL-induced NFATc1 and c-fos expression after long-term treatment with nicotine. Conclusions: We have shown that the activity of nAChRs conveys a marked effect on osteoclastogenesis in mice. Agonists of these receptors inhibited calcium oscillations in osteoclasts and blocked the RANKL-induced activation of c-fos and NFATc1. RANKL-mediated in-vitro osteoclastogenesis was reduced in α7 knockout mice, which was paralleled by increased tibial bone volume in male mice in vivo. © 2016 Mandl et al
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