3,691 research outputs found

    On an optimality property of ternary trees

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    The concept of effort is defined for rooted trees. The class of rooted trees with minimal effort is determined. The asymptotic behaviour of the minimal effort is calculated. Various choices for the effort function are considered, as well as variations of the optimality criterion

    A Gas Generating System for Complex Gas Mixtures – Multifunctional Application in PTR Method Optimization and Downstream Methanol Synthesis

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    The multifunctional applicability of a gas mixing system is presented within the scope of Carbon2Chem® for the simulation of steel mill flue gases and their application in downstream processes. A special focus is set on the parallel operation of the gas mixing system to enable PTR-MS method optimization and methanol synthesis with simulated real gas matrices. Information is gathered for the design of downstream processes and their application, where methanol synthesis is chosen as a model reaction. A proof-of-principle study is presented where operation of a catalytic reactor setup in combination with the gas mixing system and a compressor generate reproducible results. The addition of potential trace components in methanol synthesis is exemplarily demonstrated using ammonia. With respect to the PTR-MS application, the dosing of two calibration gas standards, toluene and carbonyl sulfide, via the gas mixing system were analyzed in detail. The obtained results give insight into its applicability to simulate traces and enables the further development of analytical methods for the analysis of trace impurities in the ppb and ppt range in complex gas mixtures

    Emission color-tunable oxazol(in)yl-substituted excited-state intramolecular proton transfer (ESIPT)-based luminophores

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    Oxazolinyl- and arylchalcogenazolyl-substituted hydroxyfluorenes exhibiting excited-state intramolecular proton transfer (ESIPT) are described as potent and highly modular luminophores. Emission color tuning was achieved by varying the π-expansion and the insertion of different chalcogen atoms

    Influence of Axial Workpiece Positioning during Magnetic Pulse Welding of Aluminum-Steel Joints

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    Magnetic Pulse Welding (MPW) offers a method to economically join similar and dissimilar metals without the need for external physical or chemical binders, while avoiding the adverse heating effects seen in many welding techniques. MPW allows for the fabrication of joints via the harnessing of Lorentz forces, which result from discharging a current pulse through a coil. In the process an outer piece (flyer) is accelerated onto an inner piece (parent), and welding is achieved using propagating impact fronts. There are several geometrical factors to be considered including the flyer-coil distance, the parentflyer distance, as well as the axial relationship between flyer and coil (working length). Various shapes of the front are possible and each configuration has its own advantages and drawbacks. The goal of this work is to show not only how the aforementioned parameters are related, but also ways to optimize front propagations, which are vital to the welding result. This is done primarily by determining the influence of the working length of tubular MPW specimens. It is shown that for steel-aluminum joints in the given arrangements, three different front regimes exist, which are related to geometrical factors. These results are especially useful to avoid seemingly favorable but nevertheless suboptimal conditions for flyer movement that would reduce weld quality and energy efficiency of the process

    The Turkey Ig-like receptor family: identification, expression and function.

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    The chicken leukocyte receptor complex located on microchromosome 31 encodes the chicken Ig-like receptors (CHIR), a vastly expanded gene family which can be further divided into three subgroups: activating CHIR-A, bifunctional CHIR-AB and inhibitory CHIR-B. Here, we investigated the presence of CHIR homologues in other bird species. The available genome databases of turkey, duck and zebra finch were screened with different strategies including BLAST searches employing various CHIR sequences, and keyword searches. We could not identify CHIR homologues in the distantly related zebra finch and duck, however, several partial and complete sequences of CHIR homologues were identified on chromosome 3 of the turkey genome. They were designated as turkey Ig-like receptors (TILR). Using cDNA derived from turkey blood and spleen RNA, six full length TILR could be amplified and further divided according to the typical sequence features into one activating TILR-A, one inhibitory TILR-B and four bifunctional TILR-AB. Since the TILR-AB sequences all displayed the critical residues shown to be involved in binding to IgY, we next confirmed the IgY binding using a soluble TILR-AB1-huIg fusion protein. This fusion protein reacted with IgY derived from various gallinaceous birds, but not with IgY from other bird species. Finally, we tested various mab directed against CHIR for their crossreactivity with either turkey or duck leukocytes. Whereas no staining was detectable with duck cells, the CHIR-AB1 specific mab 8D12 and the CHIR-A2 specific mab 13E2 both reacted with a leukocyte subpopulation that was further identified as thrombocytes by double immunofluorescence employing B-cell, T-cell and thrombocyte specific reagents. In summary, although the turkey harbors similar LRC genes as the chicken, their distribution seems to be distinct with predominance on thrombocytes rather than lymphocytes

    The InMAS Approach

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    The Internet Malware Analysis System (InMAS) is a modular platform for distributed, large-scale monitoring of malware on the Internet. InMAS integrates diverse tools for malware collection (using honeypots) and malware analysis (mainly using dynamic analysis). All collected information is aggregated and accessible through an intuitive and easy-to-use web interface. In this paper, we provide an overview of the structure of InMAS and the various tools it integrates. We also introduce the web frontend that displays all information on different levels of abstraction, from a coarse-grained overview down to highly detailed information on demand

    Botulinum toxin type A in the prophylactic treatment of chronic tension-type headache: A multicentre, double-blind, randomized, placebo-controlled, parallel-group study

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    We studied the safety and efficacy of 0 U, 50 U, 100 U, 150 U (five sites), 86 Usub and 100 Usub (three sites) botulinum toxin type A (BoNTA; BOTOX); Allergan, Inc., Irvine, CA, USA) for the prophylaxis of chronic tension-type headache (CTTH). Three hundred patients (62.3% female; mean age 42.6 years) enrolled. For the primary endpoint, the mean change from baseline in the number of TTH-free days per month, there was no statistically significant difference between placebo and four BoNTA groups, but a significant difference favouring placebo vs. BoNTA 150 was observed (4.5 vs. 2.8 tension headache-free days/month; P = 0.007). All treatment groups improved at day 60. Although efficacy was not demonstrated for the primary endpoint, at day 90, more patients in three BoNTA groups had \u3eor=50% decrease in tension headache days than did placebo (

    Electron-phonon renormalization of the absorption edge of the cuprous halides

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    Compared to most tetrahedral semiconductors, the temperature dependence of the absorption edges of the cuprous halides (CuCl, CuBr, CuI) is very small. CuCl and CuBr show a small increase of the gap E0E_0 with increasing temperature, with a change in the slope of E0E_0 vs. TT at around 150 K: above this temperature, the variation of E0E_0 with TT becomes even smaller. This unusual behavior has been clarified for CuCl by measurements of the low temperature gap vs. the isotopic masses of both constituents, yielding an anomalous negative shift with increasing copper mass. Here we report the isotope effects of Cu and Br on the gap of CuBr, and that of Cu on the gap of CuI. The measured isotope effects allow us to understand the corresponding temperature dependences, which we also report, to our knowledge for the first time, in the case of CuI. These results enable us to develop a more quantitative understanding of the phenomena mentioned for the three halides, and to interpret other anomalies reported for the temperature dependence of the absorption gap in copper and silver chalcogenides; similarities to the behavior observed for the copper chalcopyrites are also pointed out.Comment: 14 pages, 5 figures, submitted to Phys. Rev.

    The 63^{63}Ni(n,Îł\gamma) cross section measured with DANCE

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    The neutron capture cross section of the s-process branch nucleus 63^{63}Ni affects the abundances of other nuclei in its region, especially 63^{63}Cu and 64^{64}Zn. In order to determine the energy dependent neutron capture cross section in the astrophysical energy region, an experiment at the Los Alamos National Laboratory has been performed using the calorimetric 4Ď€\pi BaF2_2 array DANCE. The (n,Îł\gamma) cross section of 63^{63}Ni has been determined relative to the well known 197^{197}Au standard with uncertainties below 15%. Various 63^{63}Ni resonances have been identified based on the Q-value. Furthermore, the s-process sensitivity of the new values was analyzed with the new network calculation tool NETZ.Comment: 11 pages, 13 page
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