7,163 research outputs found

    Determinant representations of scalar products for the open XXZ chain with non-diagonal boundary terms

    Full text link
    With the help of the F-basis provided by the Drinfeld twist or factorizing F-matrix for the open XXZ spin chain with non-diagonal boundary terms, we obtain the determinant representations of the scalar products of Bethe states of the model.Comment: Latex file, 28 pages, based on the talk given by W. -L. Yang at Statphys 24, Cairns, Australia, 19-23 July, 201

    Charging-induced changes in reverse current-voltage characteristics of Al/Al-Rich Al 2O 3/p-Si Diodes

    Get PDF
    An Al-rich Al 2O 3 thin film was deposited on a p-type silicon substrate by radio frequency sputtering to form Al/ Al-rich Al 2O 3/p-Si diodes. The current-voltage (I-V) characteristics of the diodes were determined by carrier injection from either the Si substrate or the Al gate and by carrier transport along the tunneling paths formed by Al nanocrystals distributed in the oxide layer. The reverse I-V characteristics were greatly affected by the charge trapping in the oxide layer, i.e., the electron trapping significantly reduced the reverse current while the hole trapping enhanced the current significantly. However, the charge trapping did not produce a large change in the forward I-V characteristic. © 2009 IEEE.published_or_final_versio

    Cultural-based visual expression: Emotional analysis of human face via Peking Opera Painted Faces (POPF)

    Get PDF
    © 2015 The Author(s) Peking Opera as a branch of Chinese traditional cultures and arts has a very distinct colourful facial make-up for all actors in the stage performance. Such make-up is stylised in nonverbal symbolic semantics which all combined together to form the painted faces to describe and symbolise the background, the characteristic and the emotional status of specific roles. A study of Peking Opera Painted Faces (POPF) was taken as an example to see how information and meanings can be effectively expressed through the change of facial expressions based on the facial motion within natural and emotional aspects. The study found that POPF provides exaggerated features of facial motion through images, and the symbolic semantics of POPF provides a high-level expression of human facial information. The study has presented and proved a creative structure of information analysis and expression based on POPF to improve the understanding of human facial motion and emotion

    Spatially-resolved electronic and vibronic properties of single diamondoid molecules

    Full text link
    Diamondoids are a unique form of carbon nanostructure best described as hydrogen-terminated diamond molecules. Their diamond-cage structures and tetrahedral sp3 hybrid bonding create new possibilities for tuning electronic band gaps, optical properties, thermal transport, and mechanical strength at the nanoscale. The recently-discovered higher diamondoids (each containing more than three diamond cells) have thus generated much excitement in regards to their potential versatility as nanoscale devices. Despite this excitement, however, very little is known about the properties of isolated diamondoids on metal surfaces, a very relevant system for molecular electronics. Here we report the first molecular scale study of individual tetramantane diamondoids on Au(111) using scanning tunneling microscopy and spectroscopy. We find that both the diamondoid electronic structure and electron-vibrational coupling exhibit unique spatial distributions characterized by pronounced line nodes across the molecular surfaces. Ab-initio pseudopotential density functional calculations reveal that the observed dominant electronic and vibronic properties of diamondoids are determined by surface hydrogen terminations, a feature having important implications for designing diamondoid-based molecular devices.Comment: 16 pages, 4 figures. to appear in Nature Material

    Form Factors in N=4 Super Yang-Mills and Periodic Wilson Loops

    Full text link
    We calculate form factors of half-BPS operators in N=4 super Yang-Mills theory at tree level and one loop using novel applications of recursion relations and unitarity. In particular, we determine the expression of the one-loop form factors with two scalars and an arbitrary number of positive-helicity gluons. These quantities resemble closely the MHV scattering amplitudes, including holomorphicity of the tree-level form factor, and the expansion in terms of two-mass easy box functions of the one-loop result. Next, we compare our result for these form factors to the calculation of a particular periodic Wilson loop at one loop, finding agreement. This suggests a novel duality relating form factors to periodic Wilson loops.Comment: 26 pages, 10 figures. v2: typos fixed, comments adde

    Effect of nickel on the microstructure and mechanical property of die-cast Al–Mg–Si–Mn alloy

    Get PDF
    The effect of nickel on the microstructure and mechanical properties of a die-cast Al–Mg–Si–Mn alloy has been investigated. The results show that the presence of Ni in the alloy promotes the formation of Ni-rich intermetallics. These occur consistently during solidification in the die-cast Al–Mg–Si–Mn alloy across different levels of Ni content. The Ni-rich intermetallics exhibit dendritic morphology during the primary solidification and lamellar morphology during the eutectic solidification stage. Ni was found to be always associated with iron forming AlFeMnSiNi intermetallics, and no Al3Ni intermetallic was observed when Ni concentrations were up to 2.06 wt% in the alloy. Although with different morphologies, the Ni-rich intermetallics were identified as the same AlFeMnSiNi phase bearing a typical composition of Al[100–140](Fe,Mn)[2–7]SiNi[4–9]. With increasing Ni content, the spacing of the α-Al–Mg2Si eutectic phase was enlarged in the Al–Mg–Si–Mn alloy. The addition of Ni to the alloy resulted in a slight increase in the yield strength, but a significant decrease in the elongation. The ultimate tensile strength (UTS) increased slightly from 300 to 320 MPa when a small amount (e.g. 0.16 wt%) of Ni was added to the alloy, but further increase of the Ni content resulted in a decrease of the UTS.The Engineering and Physical Sciences Research Council (EPSRC), Technology Strategy Board (TSB) and Jaguar Land Rover (JLR) in the United Kingdom

    Form factors at strong coupling via a Y-system

    Full text link
    We compute form factors in planar N=4 Super Yang-Mills at strong coupling. Namely we consider the overlap between an operator insertion and 2n gluons. Through the gauge/string duality these are given by minimal surfaces in AdS space. The surfaces end on an infinite periodic sequence of null segments at the boundary of AdS. We consider surfaces that can be embedded in AdS_3. We derive set of functional equations for the cross ratios as functions of the spectral parameter. These equations are of the form of a Y-system. The integral form of the Y-system has Thermodynamics Bethe Ansatz form. The area is given by the free energy of the TBA system or critical value of Yang-Yang functional. We consider a restricted set of operators which have small conformal dimension

    Integer and half-integer flux-quantum transitions in a niobium/iron-pnictide loop

    Full text link
    The recent discovery of iron-based superconductors challenges the existing paradigm of high-temperature superconductivity. Owing to their unusual multi-orbital band structure, magnetism, and electron correlation, theories propose a unique sign reversed s-wave pairing state, with the order parameter changing sign between the electron and hole Fermi pockets. However, because of the complex Fermi surface topology and material related issues, the predicted sign reversal remains unconfirmed. Here we report a novel phase-sensitive technique for probing unconventional pairing symmetry in the polycrystalline iron-pnictides. Through the observation of both integer and half-integer flux-quantum transitions in composite niobium/iron-pnictide loops, we provide the first phase-sensitive evidence of the sign change of the order parameter in NdFeAsO0.88F0.12, lending strong support for microscopic models predicting unconventional s-wave pairing symmetry. These findings have important implications on the mechanism of pnictide superconductivity, and lay the groundwork for future studies of new physics arising from the exotic order in the FeAs-based superconductors.Comment: 23 pages, including 4 figures and supplementary informatio
    corecore