866 research outputs found

    Prediction as memory retrieval: timing and mechanisms

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    In our target article [Chow, W., Smith, C., Lau, E., & Phillips, C. (2015). A “bag-of-arguments” mechanism for initial verb predictions. Language, Cognition & Neuroscience. Advance online publication. doi:10.1080/23273798.2015.1066832], we investigated the predictions that comprehenders initially make about an upcoming verb as they read and provided evidence that they are sensitive to the arguments’ lexical meaning but not their structural roles. Here we synthesise findings from our work with other studies that show that verb predictions are sensitive to the arguments’ roles if more time is available for prediction. We content that prediction involves computations that may require differing amounts of time. Further, we argue that prediction can be usefully framed as a memory retrieval problem, linking prediction to independently well-understood memory mechanisms in language processing. We suggest that the delayed impact of argument roles on verb predictions may reflect a mismatch between the format of linguistic cues and target event memories. We clarify points of agreement and disagreement with the commentaries, and explain why memory access mechanisms can account for the time course of prediction

    Infrared recombination lasers pumped by low energy Nd: YAG and excimer lasers

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    24 infrared laser lines on atomic and ionic transitions have been observed in recombining plasmas by vaporizing and ionizing Cd, Pb, Sn, Zn, and Mg with low energy Nd:YAG or excimer pump-lasers. For operation and optimization of the recombination lasers separated plasma spots and a plasma confinement have been used. The operation of shorter wavelength systems by isoelectronic scaling is discussed

    Encapsulation kinetics and dynamics of carbon monoxide in clathrate hydrate.

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    Carbon monoxide clathrate hydrate is a potentially important constituent in the solar system. In contrast to the well-established relation between the size of gaseous molecule and hydrate structure, previous work showed that carbon monoxide molecules preferentially form structure-I rather than structure-II gas hydrate. Resolving this discrepancy is fundamentally important to understanding clathrate formation, structure stabilization and the role the dipole moment/molecular polarizability plays in these processes. Here we report the synthesis of structure-II carbon monoxide hydrate under moderate high-pressure/low-temperature conditions. We demonstrate that the relative stability between structure-I and structure-II hydrates is primarily determined by kinetically controlled cage filling and associated binding energies. Within hexakaidecahedral cage, molecular dynamic simulations of density distributions reveal eight low-energy wells forming a cubic geometry in favour of the occupancy of carbon monoxide molecules, suggesting that the carbon monoxide-water and carbon monoxide-carbon monoxide interactions with adjacent cages provide a significant source of stability for the structure-II clathrate framework

    Generation of short-pulse VUV and XUV radiation

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    Starting from intense short-pulse KrF (248 nm, 25 mJ, 400 fs), ArF (193 nm, 10 mJ, sim1 ps), and Ti:sapphire (810 nm, 100 mJ, 150 fs) laser systems, schemes for the generation of fixed-frequency and tunable VUV and XUV radiation by nonlinear optical techniques are investigated. With the KrF system, a four-wave mixing process in xenon yields tunable radiation in the range of 130–200 nm with output energies of, so far, 100 mgrJ in less than 1 ps. For the XUV spectral range below 100 nm, nonperturbative high-order harmonic generation and frequency mixing processes in noble gas jets are considered. To achieve tunability, the intense fixed-frequency pump laser radiation is mixed with less intense but broadly tunable radiation from short-pulse dye lasers or optical parametric generator-amplifier systems. In this way, tunability down to wavelengths of less than 40 nm has been demonstrated

    The consumption of fish cooked by different methods was related to the risk of hyperuricemia in Japanese adults: A 3-year follow-up study

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    AbstractBackground and aimsFish consumption is a recognized risk factor for elevated serum uric acid (UA) levels, hyperuricemia, and gout. However, the relationship between the consumption of fish cooked by different methods and the risk of hyperuricemia is unclear. Therefore, we aimed to investigate the relationship between the consumption of fish cooked by different methods and the risk of hyperuricemia in Japanese adults.Methods and resultsA 3-year follow-up study was conducted with 424 Japanese adults aged 29–74 years. Fish consumption was assessed using a validated self-administered dietary history questionnaire, and hyperuricemia was defined as serum UA ≄7 mg/dL in men and ≄6 mg/dL in women or the use of any anti-gout treatment. During the 3-year follow-up period, we documented 30 newly diagnosed cases of hyperuricemia. After adjusting for potential confounders, multivariate logistic regressions analysis revealed a significant positive relationship between the risk of hyperuricemia and raw (sashimi and sushi) or roasted fish consumption, but not boiled or fried fish consumption. The odds ratios (95% CI) for hyperuricemia with increasing raw fish consumption were 1.00 (reference), 2.51 (0.85, 7.39), and 3.46 (1.07, 11.14) (P for trend: 0.036). Similarly, the odds ratios (95% CI) with increasing roasted fish consumption were 1.00 (reference), 3.00 (0.75, 11.89), and 5.17 (1.30, 20.62) (P for trend: 0.018).ConclusionThis 3-year follow-up study showed that the consumption of raw or roasted fish, but not boiled or fried fish, was related with a higher risk of hyperuricemia in Japanese adults

    First principles modelling of magnesium titanium hydrides

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    Mixing Mg with Ti leads to a hydride Mg(x)Ti(1-x)H2 with markedly improved (de)hydrogenation properties for x < 0.8, as compared to MgH2. Optically, thin films of Mg(x)Ti(1-x)H2 have a black appearance, which is remarkable for a hydride material. In this paper we study the structure and stability of Mg(x)Ti(1-x)H2, x= 0-1 by first-principles calculations at the level of density functional theory. We give evidence for a fluorite to rutile phase transition at a critical composition x(c)= 0.8-0.9, which correlates with the experimentally observed sharp decrease in (de)hydrogenation rates at this composition. The densities of states of Mg(x)Ti(1-x)H2 have a peak at the Fermi level, composed of Ti d states. Disorder in the positions of the Ti atoms easily destroys the metallic plasma, however, which suppresses the optical reflection. Interband transitions result in a featureless optical absorption over a large energy range, causing the black appearance of Mg(x)Ti(1-x)H2.Comment: 22 pages, 9 figures, 4 table

    Environment-mediated structure, surface redox activity and reactivity of ceria nanoparticles

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    Nanomaterials, with potential application as bio-medicinal agents, exploit the chemical properties of a solid, with the ability to be transported (like a molecule) to a variety of bodily compartments. However, the chemical environment can change significantly the structure and hence properties of a nanomaterial. Accordingly, its surface reactivity is critically dependent upon the nature of the (biological) environment in which it resides. Here, we use Molecular Dynamics (MD) simulation, Density Functional Theory (DFT) and aberration corrected TEM to predict and rationalise differences in structure and hence surface reactivity of ceria nanoparticles in different environments. In particular we calculate reactivity 'fingerprints' for unreduced and reduced ceria nanoparticles immersed in water and in vacuum. Our simulations predict higher activities of ceria nanoparticles, towards oxygen release, when immersed in water because the water quenches the coordinative unsaturation of surface ions. Conversely, in vacuum, surface ions relax into the body of the nanoparticle to relieve coordinative unsaturation, which increases the energy barriers associated with oxygen release. Our simulations also reveal that reduced ceria nanoparticles are more active towards surface oxygen release compared to unreduced nanoceria. In parallel, experiment is used to explore the activities of ceria nanoparticles that have suffered a change in environment. In particular, we compare the ability of ceria nanoparticles, in an aqueous environment, to scavenge superoxide radicals compared to the same batch of nanoparticles, which have first been dried and then rehydrated. The latter show a distinct reduction in activity, which we correlate to a change in the redox chemistry associated with moving between different environments. The reactivity of ceria nanoparticles is therefore not only environment dependent, but is also influenced by the transport pathway or history required to reach the particular environment in which its reactivity is to be exploited. © 2013 The Royal Society of Chemistry

    Superconductivity in novel BiS2-based layered superconductor LaO1-xFxBiS2

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    Layered superconductors have provided some interesting fields in condensed matter physics owing to the low dimensionality of their electronic states. For example, the high-Tc (high transition temperature) cuprates and the Fe-based superconductors possess a layered crystal structure composed of a stacking of spacer (blocking) layers and conduction (superconducting) layers, CuO2 planes or Fe-Anion layers. The spacer layers provide carriers to the conduction layers and induce exotic superconductivity. Recently, we have reported superconductivity in the novel BiS2-based layered compound Bi4O4S3. It was found that superconductivity of Bi4O4S3 originates from the BiS2 layers. The crystal structure is composed of a stacking of BiS2 superconducting layers and the spacer layers, which resembles those of high-Tc cuprate and the Fe-based superconductors. Here we report a discovery of a new type of BiS2-based layered superconductor LaO1-xFxBiS2, with a Tc as high as 10.6 K.Comment: 23 pages, 5 figures, 1 table (table caption has been revised), to appear in J. Phys. Soc. Jp

    Microscopic Coexistence of Ferromagnetism and Superconductivity in Single-Crystal UCoGe

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    Unambiguous evidence for the microscopic coexistence of ferromagnetism and superconductivity in UCoGe (TCurie∌2.5T_{\rm Curie} \sim 2.5 K and TSCT_{\rm SC} ∌\sim 0.6 K) is reported from 59^{59}Co nuclear quadrupole resonance (NQR). The 59^{59}Co-NQR signal below 1 K indicates ferromagnetism throughout the sample volume, while nuclear spin-lattice relaxation rate 1/T11/T_1 in the ferromagnetic (FM) phase decreases below TSCT_{\rm SC} due to the opening of the superconducting(SC) gap. The SC state was found to be inhomogeneous, suggestive of a self-induced vortex state, potentially realizable in a FM superconductor. In addition, the 59^{59}Co-NQR spectrum around TCurieT_{\rm Curie} show that the FM transition in UCoGe possesses a first-order character, which is consistent with the theoretical prediction that the low-temperature FM transition in itinerant magnets is generically of first-order.Comment: 5 pages, 5 figure

    Heavy-Mass Behavior of Ordered Perovskites ACu3Ru4O12 (A = Na, Ca, La)

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    We synthesized ACu3Ru4O12 (A = Na, Na0.5Ca0.5, Ca, Ca0.5La0.5, La) and measured their DC magnetization, AC susceptibility, specific heat, and resistivity, in order to investigate the effects of the hetero-valent substitution. A broad peak in the DC magnetization around 200 K was observed only in CaCu3Ru4O12, suggesting the Kondo effect due to localized Cu2+ ions. However, the electronic specific heat coefficients exhibit large values not only for CaCu3Ru4O12 but also for all the other samples. Moreover, the Wilson ratio and the Kadowaki-Woods ratio of our samples are all similar to the values of other heavy-fermion compounds. These results question the Kondo effect as the dominant origin of the mass enhancement, and rather indicate the importance of correlations among itinerant Ru electrons.Comment: 6 pages, 6 figures, to be published in J. Phys. Soc. Jp
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