1,261 research outputs found

    Presymplectic representation of bi-Hamiltonian chain

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    Liouville integrable systems, which have bi-Hamiltonian representation of the Gel'fand-Zakharevich type, are considered. Bi-presymplectic representation of one-Casimir bi-Hamiltonian chains and weakly bi-presymplectic representation of multi-Casimir bi-Hamiltonian chains are constructed. The reduction procedure for Poisson and presymplectic structures is presented.Comment: 17 pages, to appear in J. Phys. A: Math. Ge

    Bidirectional Scatter Measurements of a Guided-mode Resonant Filter Photonic Crystal Structure

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    This work investigates the Bidirectional Scatter Distribution Function (BSDF) at incident angles other than normal and at 544-nm wavelength of a Guided Mode Resonance Filter (GMRF) Photonic Crystal (PC) structure designed for normally incident light at 532 nm. Strong out-coupling of PC diffraction orders into both the transmitted and reflected hemispheres was observed specifically at a 25.7° incidence angle, which we attribute to this incident angle/wavelength pair being a good match to the ( ± 1, 0) PC grating mode. BSDF measurements at incident angles of 15° and 35° also displayed some out-coupled diffraction, though much lower in magnitude, and are also attributed to being a weaker match to the ( ± 1, 0) PC grating mode. Three-dimensional finite-difference time-domain Maxwell\u27s equation simulations demonstrate that since this GMRF was designed for complete destructive interference of the transmitted light upon normal incidence, stronger out-coupling of the diffraction is expected for modal solutions as the angle of incidence increases. © 2012 Optical Society of America

    The occurrence of wakefieldite, a rare earth element vanadate, in the rhyolitic Joe Lott Tuff, Utah, USA

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    The high-silica rhyolitic Joe Lott Tuff was erupted at 19.2 ± 0.4 Ma from the Mount Belknap caldera, SW Utah. Certain units in the tuff contain two species of wakefieldite, the Nd- A nd Y-dominant types. They occur in disseminated streaks and patches in association with rhodochrosite, calcite, Fe oxide, cerite-(Ce), and a Mn silicate (caryopilite?), thought to have been deposited from hydrothermal fluids. The wakefieldites contain the highest levels of As (≤15.34 wt.% As2O5) and P (≤5.7 wt.% P2O5) yet recorded in this mineral, indicating significant solid solution towards chernovite-(Y) and xenotime-(Y). Thorium levels are also unusually high (≤14.2 wt.% ThO2). The source of the hydrothermal fluid(s) is unknown but might be related to uranium mineralisation in the region, in that As, V and U are commonly associated in such deposits. © 2019 Mineralogical Society of Great Britain and Ireland

    Parents who refuse or delay HPV vaccine: Differences in vaccination behavior, beliefs, and clinical communication preferences

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    Background: We sought to estimate the national prevalence of HPV vaccine refusal and delay in a nationally-representative sample of parents of adolescents. We also compared parents who refused versus delayed HPV vaccine in terms of their vaccination beliefs and clinical communication preferences. Methods: In 2014 to 2015, we conducted an online survey of 1,484 US parents who reported on an 11- to 17-year-old child in their household. We used weighted multinomial logistic regression to assess correlates of HPV vaccine refusal and delay. Results: Overall, 28% of parents reported that they had ever “refused or decided not to get” HPV vaccine for their child, and an additional 8% of parents reported that they had “delayed or put off getting” HPV vaccine. Compared to no refusal/delay, refusal was associated with lower confidence in adolescent vaccination (relative risk ratio [RRR] = 0.66, 95% confidence interval [CI], 0.48–0.91), lower perceived HPV vaccine effectiveness (RRR = 0.68, 95% CI, 0.50–0.91), and higher perceived harms (RRR = 3.49, 95% CI, 2.65–4.60). In contrast, delay was associated with needing more information (RRR = 1.76, 95% CI, 1.08–2.85). Most parents rated physicians and information sheets as helpful for making decisions about HPV vaccination, although parents who reported refusal endorsed these resources less often. Conclusions: Our findings suggest that HPV vaccine refusal is common among parents of adolescents and may have increased relative to previous estimates. Because the vaccination beliefs and communication preferences of parents who refuse appear to differ from those who delay, targeted communication strategies may be needed to effectively address HPV vaccine hesitancy

    2-Sulfonylpyrimidines as Privileged Warheads for the Development of S. aureus Sortase A Inhibitors

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    Staphylococcus aureus is one of the most frequent causes of nosocomial and community-acquired infections, with emerging multiresistant isolates causing a significant burden to public health systems. We identified 2-sulfonylpyrimidines as a new class of potent inhibitors against S. aureus sortase A acting by covalent modification of the active site cysteine 184. Series of derivatives were synthesized to derive structure-activity relationship (SAR) with the most potent compounds displaying low micromolar K(I) values. Studies on the inhibition selectivity of homologous cysteine proteases showed that 2-sulfonylpyrimidines reacted efficiently with protonated cysteine residues as found in sortase A, though surprisingly, no reaction occurred with the more nucleophilic cysteine residue from imidazolinium-thiolate dyads of cathepsin-like proteases. By means of enzymatic and chemical kinetics as well as quantum chemical calculations, it could be rationalized that the S ( N )Ar reaction between protonated cysteine residues and 2-sulfonylpyrimidines proceeds in a concerted fashion, and the mechanism involves a ternary transition state with a conjugated base. Molecular docking and enzyme inhibition at variable pH values allowed us to hypothesize that in sortase A this base is represented by the catalytic histidine 120, which could be substantiated by QM model calculation with 4-methylimidazole as histidine analog

    Provider communication and HPV vaccination: The impact of recommendation quality

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    Receiving a healthcare provider’s recommendation is a strong predictor of HPV vaccination, but little is known empirically about which types of recommendation are most influential. Thus, we sought to investigate the relationship between recommendation quality and HPV vaccination among U.S. adolescents

    EVALUATION OF MODERN HERITAGE ASSETS IN POZNAN USING MONOTONIC DECISION RULES

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    The protection of cultural heritage is an important task of communities on various levels of social organization. The institutionalization of the processes of protection of modern heritage assets provides the necessary instruments (legislative, juridical, financial) enabling the actual realization of the assumed tasks. The criterion of age, which is still a dominating premise for monument protection, proved not to be sufficient, especially concerning protection of monuments of Modernism. A step that led to the determination of the value of individual architectural objects of the 20th century was the establishment of 10 evaluation criteria proposed by historians of architecture in Warsaw, and afterwards in Poznan.In this work, we focus on the architectural value of post-war buildings, which are most difficult to evaluate. Furthermore, we wanted to apply AI to objectify the process of decision making. The adequacy of the Dominance-based Rough Set Approach (DRSA) method has been established. This method takes into account preference orders on criteria and models patterns observed in data in terms of monotonic “if &hellip;, then &hellip;” decision rules.</p
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