247 research outputs found

    Modifying the photodetachment near a metal surface by a weak electric field

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    We show the photodetachment cross sections of H near a metal surface can be modified using a weak static electric field. The modification is possible because the oscillatory part of the cross section near a metal surface is directly connected with the transit-time and the action of the detached-electron closed-orbit which can be changed systematically by varying the static electric field strength. Photodetachment cross sections for various photon energies and electric field values are calculated and displayed.Comment: 16 pages, 7 figure

    Renormalization group scale-setting from the action - a road to modified gravity theories

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    The renormalization group (RG) corrected gravitational action in Einstein-Hilbert and other truncations is considered. The running scale of the renormalization group is treated as a scalar field at the level of the action and determined in a scale-setting procedure recently introduced by Koch and Ramirez for the Einstein-Hilbert truncation. The scale-setting procedure is elaborated for other truncations of the gravitational action and applied to several phenomenologically interesting cases. It is shown how the logarithmic dependence of the Newton's coupling on the RG scale leads to exponentially suppressed effective cosmological constant and how the scale-setting in particular RG corrected gravitational theories yields the effective f(R)f(R) modified gravity theories with negative powers of the Ricci scalar RR. The scale-setting at the level of the action at the non-gaussian fixed point in Einstein-Hilbert and more general truncations is shown to lead to universal effective action quadratic in Ricci tensor.Comment: v1: 15 pages; v2: shortened to 10 pages, main results unchanged, published in Class. Quant. Gra

    EXCIMER LAMP OXIDANT PRODUCTION AND REMOVAL OF CALCIUM FROM COOLING TOWER WATER

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    Pulsar UV system (PUV) currently represents the most mature excimer lamp technology. PUV system provides pulsed high-energy blackbody in broadband width. The production, generation and destruction of oxidant radicals by PUV equipment was investigated in this work and modeled by appropriate mathematical expressions. From the mass balance, solving differential equation, this model was derived: concentration versus time for oxidant radical production by PUV equipment. Removal of calcium from the bulk solution and cooling tower water was investigated by using 1) the PUV equipment, 2) the Ozonator and 3) a combination of the PUV equipment and the Ozonator. The removal of calcium was verified. The kinetics of calcium removal from water in all three cases was determined

    Examining flight time, cognitive reflection, workload, stress and metacognition on decision making performance for pilots during flight simulation

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    Despite technological advancements, human decision errors still contribute to civil aviation accidents. This study investigated whether flight time, cognitive reflection, task-load, metacognition, and perceived stress predicted decision-making (DM) performance during two in-flight training simulations with 104 commercial pilots at Bogota International Airport. Hierarchical regression analysis revealed that the predictors accounted for 56% of the variance. Cognitive reflection, flight time and performance task load emerged as significant positive predictors. Cognitive reflection significantly moderated the relationship between flight time and DM performance, with pilots scoring lower on cognitive reflection showing improved DM with increased flight time, while controlling for performance task load. The study did not find significant relationships between stress metacognition and DM performance. The study emphasises the significance of advanced training methods in improving pilots’ DM, especially for those with low cognitive reflection. Future research should expand to multiple airlines, address gender balance, and incorporate direct measures of metacognitive monitoring

    Establishing the database of inundation potential in Taiwan

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    Copyright © Springer 2006. The final publication is available at Springer via http://dx.doi.org/10.1007/s11069-005-4659-7The structural measure was the major solution for flood defense in Taiwan. However, the measure is always limited to the design standard and cannot prevent the damages when floods exceed certain scale. Therefore, non-structural measures for flood mitigation are the indispensable complements to structural solutions. The study introduces the establishment of inundation potential database that provides required information for the non-structural measures in Taiwan. The database was built by numerical simulations, based on different rainfall scenarios, and has been applied by the local governments of Taiwan for land use managements, flood warning systems, emergency responses, and flood insurance programs to reduce the flood damages and impacts.National Science Council, Executive Yuan, ROC

    Slower is not always better: Response-time evidence clarifies the limited role of miserly information processing in the Cognitive Reflection Test

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    We report a study examining the role of `cognitive miserliness' as a determinant of poor performance on the standard three-item Cognitive Reflection Test (CRT). The cognitive miserliness hypothesis proposes that people often respond incorrectly on CRT items because of an unwillingness to go beyond default, heuristic processing and invest time and effort in analytic, reflective processing. Our analysis (N = 391) focused on people's response times to CRT items to determine whether predicted associations are evident between miserly thinking and the generation of incorrect, intuitive answers. Evidence indicated only a weak correlation between CRT response times and accuracy. Item-level analyses also failed to demonstrate predicted response time differences between correct analytic and incorrect intuitive answers for two of the three CRT items. We question whether participants who give incorrect intuitive answers on the CRT can legitimately be termed cognitive misers and whether the three CRT items measure the same general construct

    Suppression of Decoherence in Fast-Atom Diffraction at Surfaces

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    Scattering of fast neutral atoms with keV kinetic energies at alkali-halide surfaces under grazing angles displays intriguing diffraction patterns. The surprisingly strong persistence of quantum coherence despite the impulsive interaction with an environment at solid state density and elevated temperatures raises fundamental questions such as to the suppression of decoherence and of the quantum-to-classical crossover. We present an ab initio simulation of the quantum diffraction of fast helium beams at a LiF (100) surface in the direction and compare with recent experimental diffraction data. From the quantitative reconstruction of diffraction images the vertical LiF-surface reconstruction, or buckling, can be determined

    Synthesis and Antimicrobial Activity of Short Analogues of the Marine Antimicrobial Peptide Turgencin A: Effects of SAR Optimizations, Cys-Cys Cyclization and Lipopeptide Modifications

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    We have synthesised short analogues of the marine antimicrobial peptide Turgencin A from the colonial Arctic ascidian Synoicum turgens. In this study, we focused on a central, cationic 12-residue Cys-Cys loop region within the sequence. Modified (tryptophan- and arginine-enriched) linear peptides were compared with Cys-Cys cyclic derivatives, and both linear and Cys-cyclic peptides were N-terminally acylated with octanoic acid (C8 ), decanoic acid (C10) or dodecanoic acid (C12). The highest antimicrobial potency was achieved by introducing dodecanoic acid to a cyclic Turgencin A analogue with low intrinsic hydrophobicity, and by introducing octanoic acid to a cyclic analogue displaying a higher intrinsic hydrophobicity. Among all tested synthetic Turgencin A lipopeptide analogues, the most promising candidates regarding both antimicrobial and haemolytic activity were C12-cTurg-1 and C8-cTurg-2. These optimized cyclic lipopeptides displayed minimum inhibitory concentrations of 4 µg/mL against Staphylococcus aureus, Escherichia coli and the fungus Rhodothorula sp. Mode of action studies on bacteria showed a rapid membrane disruption and bactericidal effect of the cyclic lipopeptides. Haemolytic activity against human erythrocytes was low, indicating favorable selective targeting of bacterial cells
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