749 research outputs found
The minimal conformal O(N) vector sigma model at d=3
For the minimal O(N) sigma model, which is defined to be generated by the
O(N) scalar auxiliary field alone, all n-point functions, till order 1/N
included, can be expressed by elementary functions without logarithms.
Consequently, the conformal composite fields of m auxiliary fields possess at
the same order such dimensions, which are m times the dimension of the
auxiliary field plus the order of differentiation.Comment: 15 page
Massive Fields of Arbitrary Integer Spin in Symmetrical Einstein Space
We study the propagation of gauge fields with arbitrary integer spins in the
symmetrical Einstein space of any dimensionality. We reduce the problem of
obtaining a gauge-invariant Lagrangian of integer spin fields in such
background to an purely algebraic problem of finding a set of operators with
certain features using the representation of high-spin fields in the form of
some vectors of pseudo-Hilbert space. We consider such construction in the
linear order in the Riemann tensor and scalar curvature and also present an
explicit form of interaction Lagrangians and gauge transformations for massive
particles with spins 1 and 2 in terms of symmetrical tensor fields.Comment: 15 pages, latex, no figures,minor change
Properties and efficiency of catalysts produced by an ION beam processing technology
Paper presents the test results and properties of catalysts produced by an ion implantation technique. New catalysts showed the same efficiency with much lower expense of noble metals as compared with the catalysts produce by an impregnation. Also shown, that the ion bombardment did not reduce the specific surface area of the catalyst.Приведены свойства и результаты испытаний катализаторов, полученных путем ионной имплантации. По сравнению с катализаторами, полученными обычными технологиями, опытные катализаторы показывают те же значения коэффициента нейтрализации при значительно меньшем содержании благородных металлов. Показано, что ионная бомбардировка не уменьшает эффективную поверхность носителей
Direct evidence for a piezoelectriclike effect in coherently strained SiGe/Si heterostructures
A hybrid acoustic spectroscopy technique has been used to demonstrate the (reversible) conversion of high frequency electric fields into longitudinal acoustic waves within a modulation-doped pseudomorphic Si/Si0.88Ge0.12/Si heterostructure. This provides compelling evidence for the existence of a piezoelectriclike coupling within such structures
Novel bimetallic 1%M-Fe/Al2O3-Cr2O3 (2:1) (M = Ru, Au, Pt, Pd) catalysts for Fischer-Tropsch synthesis
The main objective of this work was to study the physicochemical and catalytic properties of bimetallic supported catalysts [1%M-Fe/Al2O3-Cr2O3 (2:1) (M = Ru, Au, Pt, Pd)] in Fischer-Tropsch synthesis. Furthermore, the study investigated the effect of noble metal addition to iron-supported catalysts on their physicochemical properties and reactivity. The physicochemical properties of the catalysts were studied using a range of characterization techniques such as X-ray diffraction (XRD), temperature-programmed reduction (TPR-H2), temperature-programmed desorption of ammonia (TPD-NH3) and BET (Brunauer – Emmett - Teller method). The activity tests were performed by Fischer-Tropsch synthesis in a high-pressure fixed-bed reactor using a gas mixture of H2 and CO with a molar ratio of 1:1. The correlation between the physicochemical properties of the investigated catalysts and their catalytic performance in CO hydrogenation was also investigated. The reactivity results showed that the most active system exhibited a high specific surface area, the highest total acidity and was the most reducible catalyst compared to the other catalysts tested. In addition, the Au–Fe system showed high selectivity towards liquid product formation during CO hydrogenation
Children’s Reading of Sublexical Units in Years Three to Five: A Combined Analysis of Eye-Movements and Voice Recording
Purpose
Children progress from making grapheme–phoneme connections to making grapho-syllabic connections before whole-word connections during reading development (Ehri, 2005a). More is known about the development of grapheme–phoneme connections than is known about grapho-syllabic connections. Therefore, we explored the trajectory of syllable use in English developing readers during oral reading.
Method
Fifty-one English-speaking children (mean age: 8.9 years, 55% females, 88% monolinguals) in year groups three, four, and five read aloud sentences with an embedded target word, while their eye movements and voices were recorded. The targets contained six letters and were either one or two syllables.
Result
Children in grade five had shorter gaze duration, shorter articulation duration, and larger spatial eye-voice span (EVS) than children in grade four. Children in grades three and four did not significantly differ on these measures. A syllable number effect was found for gaze duration but not for articulation duration and spatial EVS. Interestingly, one-syllable words took longer to process compared to two-syllable words, suggesting that more syllables may not always signify greater processing difficulty.
Conclusion
Overall, children are sensitive to sublexical reading units; however, due to sample and stimuli limitations, these findings should be interpreted with caution and further research conducted
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