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  CPH Theory is based  on  Generalized light velocity from energy  into mass.


CPH Theory in Journals



A few interestings articles





A few interestings articles


White light generation by resonant nonradiative energy transfer from epitaxial InGaN/GaN quantum wells to colloidal CdSe/ZnS core/shell quantum dots
    Sedat Nizamoglu, Emre Sari, Jong-Hyeob Baek, In-Hwan Lee and Hilmi
    Volkan Demir
    2008 New J. Phys. 10 123001 (10pp)

    Full text PDF: http://www.iop.org/EJ/article/-alert=29894/1367-2630/10/12/123001/njp8_12_123001.pdf
    Full text HTML: http://www.iop.org/EJ/article/-alert=29894/1367-2630/10/12/123001/njp8_12_123001.html

    We propose and demonstrate white-light-generating nonradiative energy transfer (ET) from epitaxial quantum wells (QWs) to colloidal quantum dots (QDs) in their close proximity. This proof-of-concept hybrid color-converting system consists of chemically synthesized red-emitting CdSe/ZnS core/shell heteronanocrystals intimately integrated on epitaxially grown cyan-emitting InGaN/GaN QWs. The
    white light is generated by the collective luminescence of QWs and
    QDs, for which the dot emission is further increased by 63% with
    nonradiative ET, setting the operating point in the white region of
    CIE chromaticity diagram. Using cyan emission at 490 nm from the
    QWs and red emission at 650 nm from the nanocrystal (NC)
    luminophors, we obtain warm white light generation with a
    correlated color temperature of Tc = 3135 K and tristimulus
    coordinates of (x,y) = (0.42, 0.39) in the white region. By
    analyzing the time-resolved radiative decay of these NC emitters in
    our hybrid system with a 16 ps time resolution, the luminescence
    kinetics reveals a fast ET with a rate of (2 ns)-1 using a
    multiexponential fit with χ 2 = 1.0171.

    Fingering instabilities on reaction fronts in the CO oxidation reaction  on Pt(100)
    D Bilbao and J Lauterbach
    2008 New J. Phys. 10 123002 (10pp)
    Full text PDF: http://www.iop.org/EJ/article/-alert=29894/1367-2630/10/12/123002/njp8_12_123002.pdf
    Full text HTML: http://www.iop.org/EJ/article/-alert=29894/1367-2630/10/12/123002/njp8_12_123002.html

    Fingering instabilities arising from local perturbations to planar
    reaction fronts in the CO oxidation reaction on Pt(100) are
    presented. CO oxidation represents a heterogeneous nonlinear system
    with the necessary kinetic and diffusive transport properties to
    support the development of fingered wave fronts. External forcing
    was utilized to create CO wave fronts on an otherwise monostable,
    O-covered surface, which, upon destabilization, gave rise to
    fingers of adsorbed CO extending into the O adlayer ahead of the
    reaction front. Finger spreading and tip-splitting were observed as
    the finger pattern evolved towards an intrinsic wavelength,
    independent of the length of the reaction front, calculated to be
    approximately 40 um. Our data also show the presence of a shielding
    process, where at wavelengths less than twice the observed
    intrinsic value, additional fingers were created on the reaction
    front through a tip-splitting bifurcation of an existing finger. At
    wavelengths greater than twice the intrinsic value, additional
    fingers formed in the troughs between adjacent fingers, apparently
    unaffected by the presence of the larger surrounding fingers.

    Superconductivity at 34.7 K in the iron arsenide Eu0.7Na0.3Fe2As2
    Yanpeng Qi, Zhaoshun Gao, Lei Wang, Dongliang Wang, Xianping Zhang and
    Yanwei Ma
    2008 New J. Phys. 10 123003 (6pp)
    Full text PDF: http://www.iop.org/EJ/article/-alert=29894/1367-2630/10/12/123003/njp8_12_123003.pdf
    Full text HTML: http://www.iop.org/EJ/article/-alert=29894/1367-2630/10/12/123003/njp8_12_123003.html

    EuFe2As2 is a member of the ternary iron arsenide family. Similar to
    BaFe2As2 and SrFe2As2, EuFe2As2 exhibits a clear anomaly in
    resistivity near 200 K. Here, we report the discovery of
    superconductivity in Eu0.7Na0.3Fe2As2 by partial substitution of
    the europium site with sodium. ThCr2Si2 tetragonal structure, as
    expected for EuFe2As2, is formed as the main phase for the
    composition Eu0.7Na0.3Fe2As2. Resistivity measurements reveal that
    the transition temperature Tc as high as 34.7 K is observed in this
    compound. The rate of Tc suppression with the applied magnetic
    field is 3.87 T K−1, giving an extrapolated zero-temperature
    upper critical field of 100 T. It demonstrates a very encouraging
    application of the new superconductors.

    Magnetization dynamics in optically excited nanostructured nickel films
    Georg M Mu"ller, Gerrit Eilers, Zhao Wang, Malte Scherff, Ran Ji,
    Kornelius Nielsch, Caroline A Ross and Markus Mu"nzenberg
    2008 New J. Phys. 10 123004 (9pp)
    Full text PDF: http://www.iop.org/EJ/article/-alert=29894/1367-2630/10/12/123004/njp8_12_123004.pdf
    Full text HTML: http://www.iop.org/EJ/article/-alert=29894/1367-2630/10/12/123004/njp8_12_123004.html

    In this work, the laser-induced magnetization dynamics of
    nanostructured nickel films is investigated. The influence of the
    nanosize is discussed considering the timescale of hundreds of
    femtoseconds as well as the GHz regime. While no nanosize effect is
    observed on the short timescale, the excited magnetic mode in the
    GHz regime can be identified by comparison with micromagnetic
    simulations. The thickness dependence reveals insight into the
    dipole interaction between single nickel structures. Also,
    transient reflectivity changes are discussed.

    Creation of three-species 87Rb-40K-6Li molecules: interfering for the best
    Hui Jing, Yajing Jiang, Weiping Zhang and Pierre Meystre
    2008 New J. Phys. 10 123005 (11pp)
    Full text PDF: http://www.iop.org/EJ/article/-alert=29894/1367-2630/10/12/123005/njp8_12_123005.pdf
    Full text HTML: http://www.iop.org/EJ/article/-alert=29894/1367-2630/10/12/123005/njp8_12_123005.html

    An ultracold three-species Bose-Fermi-Fermi degenerate atomic mixture
    87Rb-40K-6Li was realized very recently (Tagliber M et al 2008
    Phys. Rev. Lett. 100 010401). Here, we study the creation of
    heteronuclear triatomic molecules in this mixture, and show that a
    constructive triple-path interference can lead to an almost ideal
    conversion rate, in comparison with the single- or double-path
    cases. The important effect of the initial population imbalance on
    the atom-molecule dark state is also investigated.

    Subtracting photons from arbitrary light fields: experimental test of coherent state invariance by single-photon annihilation
    A Zavatta, V Parigi, M S Kim and M Bellini
    2008 New J. Phys. 10 123006 (10pp)
    Full text PDF: http://www.iop.org/EJ/article/-alert=29894/1367-2630/10/12/123006/njp8_12_123006.pdf
    Full text HTML: http://www.iop.org/EJ/article/-alert=29894/1367-2630/10/12/123006/njp8_12_123006.html

    The operator annihilating a single quantum of excitation in a bosonic
    field is one of the cornerstones for the interpretation and
    prediction of the behavior of the microscopic quantum world. Here
    we present a systematic experimental study of the effects of
    single-photon annihilation on some paradigmatic light states. In
    particular, by demonstrating the invariance of coherent states by
    this operation, we provide the first direct verification of their
    definition as eigenstates of the photon annihilation operator.

    Vector frequency-comb Fourier-transform spectroscopy for characterizing

    T Ganz, M Brehm, H G von Ribbeck, D W van der Weide and F Keilmann
    2008 New J. Phys. 10 123007 (14pp)
    Full text PDF: http://www.iop.org/EJ/article/-alert=29894/1367-2630/10/12/123007/njp8_12_123007.pdf
    Full text HTML: http://www.iop.org/EJ/article/-alert=29894/1367-2630/10/12/123007/njp8_12_123007.html

    We determine infrared transmission amplitude and phase spectra of
    metamaterial samples at well-defined incidence and polarization
    with a vector ('asymmetric') frequency-comb Fourier-transform
    spectrometer (c-FTS) that uses no moving elements. The
    metamaterials are free-standing metallic hole arrays; we study
    their resonances in the 7-13 um and 100-1000 um wavelength regions
    due both to interaction with bulk waves (Wood anomaly) and with
    leaky surface plasmon polaritons (near-unity transmittance,
    coupling features and dispersion). Such complex-valued transmission
    and reflection spectra could be used to compute a metamaterial's
    complex dielectric function directly, as well as its magnetic and
    magneto-optical permeability functions.

    Spatial and temporal development of the plasma potential in differently
    configured pulsed magnetron discharges

    Th Welzel, Th Dunger, B Liebig and F Richter
    2008 New J. Phys. 10 123008 (16pp)
    Full text PDF: http://www.iop.org/EJ/article/-alert=29894/1367-2630/10/12/123008/njp8_12_123008.pdf
    Full text HTML: http://www.iop.org/EJ/article/-alert=29894/1367-2630/10/12/123008/njp8_12_123008.html

    Time-resolved emissive probe measurements have been performed to study
    the spatio-temporal development of the plasma potential in an
    asymmetric bipolar pulsed magnetron discharge. The influence of the
    substrate potential as well as of the substrate position has been
    investigated while the further conditions were the same. To access
    the entire potential range which was between -100 V and + 400 V and
    to obtain sufficient time-resolution of the emissive probe,
    different heating currents had to be used. The plasma potential has
    been found to be typically close to zero in the 'on' phase, about +
     40 V in the stable 'off' phase and up to +  400 V at the beginning
    of the 'off' phase, which is in agreement with the results of other
    authors. However, the positive values in the 'off' phase are
    generally lower than those reported and stay mostly below the
    target potential. This is explained by macroscopic considerations
    of the quasineutrality of the plasma taking into account a magnetic
    and geometrical shielding of the target, acting as an anode in the
    'off' phase, and the potential and position of the substrate holder
    and environment.

    Illustration of quantum complementarity using single photons interfering on a grating
    V Jacques, N D Lai, A Dre'au, D Zheng, D Chauvat, F Treussart, P
    Grangier and J-F Roch
    2008 New J. Phys. 10 123009 (11pp)
    Full text PDF: http://www.iop.org/EJ/article/-alert=29894/1367-2630/10/12/123009/njp8_12_123009.pdf
    Full text HTML: http://www.iop.org/EJ/article/-alert=29894/1367-2630/10/12/123009/njp8_12_123009.html

    A recent experiment performed by Afshar et al (2007 Found. Phys. 37
    295-305) has been interpreted as a violation of Bohr's
    complementarity principle between interference visibility and
    which-path information (WPI) in a two-path interferometer. We have
    reproduced this experiment, using true single-photon pulses
    propagating in a two-path wavefront-splitting interferometer
    realized with a Fresnel's biprism, and followed by a grating with
    adjustable transmitting slits. The measured values of interference
    visibility V and WPI, characterized by the distinguishability
    parameter D, are found to obey the complementarity relation
    V2+D2⩽1. This result demonstrates that the experiment can be
    perfectly explained by the standard interpretation of quantum

    A stochastic theory for temporal fluctuations in self-organized
    critical systems

    M Rypdal and K Rypdal
    2008 New J. Phys. 10 123010 (11pp)
    Full text PDF: http://www.iop.org/EJ/article/-alert=29894/1367-2630/10/12/123010/njp8_12_123010.pdf
    Full text HTML: http://www.iop.org/EJ/article/-alert=29894/1367-2630/10/12/123010/njp8_12_123010.html

    A stochastic theory for the toppling activity in sandpile models is
    developed, based on a simple mean-field assumption about the
    toppling process. The theory describes the process as an
    anti-persistent Gaussian walk, where the diffusion coefficient is
    proportional to the activity. It is formulated as a generalization
    of the Ito^ stochastic differential equation with an
    anti-persistent fractional Gaussian noise source and a
    deterministic drift term. An essential element of the theory is
    rescaling to obtain a proper thermodynamic limit. When subjected to
    the most relevant statistical tests, the signal generated by the
    stochastic equation is indistinguishable from the temporal features
    of the toppling process obtained by numerical simulation of the
    Bak-Tang-Wiesenfeld sandpile.

    Laser heating of large noble gas clusters: from the resonant to the relativistic interaction regimes
    E T Gumbrell, A S Moore, J A Lazarus, E L Clark, P M Nilson, W J
    Garbett, A J Comley, J S Robinson, M Hohenberger, R D Edwards, R E
    Eagleton, R J Clarke, D R Symes and R A Smith
    2008 New J. Phys. 10 123011 (19pp)
    Full text PDF: http://www.iop.org/EJ/article/-alert=29894/1367-2630/10/12/123011/njp8_12_123011.pdf
    Full text HTML: http://www.iop.org/EJ/article/-alert=29894/1367-2630/10/12/123011/njp8_12_123011.html

    Wide-ranging measurements of sub-picosecond laser interactions with
    large noble gas cluster targets have been conducted in order to
    help clarify the nature and extent of the underlying laser-plasma
    heating. Within the sub-relativistic vacuum irradiance range of
    1016-1017 W cm-2, we find that electron temperatures measured with
    continuum x-ray spectroscopy exhibit a pronounced multi-keV
    enhancement. Analysis indicates this behaviour to be consistent
    with collisional or collisionless resonant heating mechanisms. We
    also present the first measurements of laser-to-cluster energy
    deposition at relativistic vacuum irradiances, our data
    demonstrating absorption fractions of 90% or more. Optical probing
    was used to resolve the onset of a supersonic ionization front
    resulting from this very high absorption, and shows that despite
    significant pre-focus heating, the greatest plasma energy densities
    can be generated about the vacuum focus position. Electron energy
    spectra measurements confirm that laser-plasma super-heating
    occurs, and together with ion data establish that relativistic
    laser-plasma coupling in atomic clusters can take place without
    significant MeV particle beam production. In conjunction with
    optical self-emission data, the optical probing also indicates
    laser pre-pulse effects at peak vacuum irradiance of 5 x 1019 W
    cm-2. Laser absorption, plasma heating and energy transport data
    are supported throughout with analytical and numerical modelling.

    Coherent exciton transport on scale-free networks
    X P Xu and F Liu
    2008 New J. Phys. 10 123012 (9pp)
    Full text PDF: http://www.iop.org/EJ/article/-alert=29894/1367-2630/10/12/123012/njp8_12_123012.pdf
    Full text HTML: http://www.iop.org/EJ/article/-alert=29894/1367-2630/10/12/123012/njp8_12_123012.html

    The coherent exciton transport on a class of deterministic and random
    scale-free networks (DSFNs and RSFNs) generated by simple rules is
    studied in this paper. The coherent exciton dynamics is modeled by
    continuous-time quantum walks, and we calculate the transition
    probabilities between two nodes of the networks. We find that the
    transport depends on the initial nodes of the excitation. For
    DSFNs, the probabilities of finding the excitation at the initial
    central nodes are nearly periodic, in contrast to the flat behavior
    found for RSFNs. In the long time limit, the transition
    probabilities on DSFNs show characteristic patterns with identical
    values. For RSFNs, we find that the excitation is most likely to be
    found at the initial nodes with high connectivity. All these
    features of quantum transport are significantly different from
    those of the classical transport modeled by continuous-time random

    Coupled quantum electrodynamics in photonic crystal cavities towards
    controlled phase gate operations

    Y-F Xiao, J Gao, X-B Zou, J F McMillan, X Yang, Y-L Chen, Z-F Han, G-C
    Guo and C W Wong
    2008 New J. Phys. 10 123013 (13pp)
    Full text PDF: http://www.iop.org/EJ/article/-alert=29894/1367-2630/10/12/123013/njp8_12_123013.pdf
    Full text HTML: http://www.iop.org/EJ/article/-alert=29894/1367-2630/10/12/123013/njp8_12_123013.html

    In this paper, a scalable photonic crystal cavity array, in which
    single embedded quantum dots (QDs) are coherently interacting, is
    studied theoretically. Firstly, we examine the spectral character
    and optical delay brought about by the coupled cavities interacting
    with single QDs, in an optical analogue to electromagnetically
    induced transparency. Secondly, we then examine the usability of
    this coupled QD-cavity system for quantum phase gate operation and
    our numerical examples suggest that a two-qubit system with
    fidelity above 0.99 and photon loss below 0.04 is possible.

    Vacuum fluctuations induced entanglement between two mesoscopic systems
    H T Ng and K Burnett

    2008 New J. Phys. 10 123014 (8pp)
    Full text PDF: http://www.iop.org/EJ/article/-alert=29894/1367-2630/10/12/123014/njp8_12_123014.pdf
    Full text HTML: http://www.iop.org/EJ/article/-alert=29894/1367-2630/10/12/123014/njp8_12_123014.html

    We study the dynamics of a pair of molecular ensembles trapped inside a
    superconducting resonator through which they are strongly coupled
    via a microwave field mode. We find that entanglement can be
    generated via 'vacuum fluctuations' even when the molecules and
    cavity field are initially prepared in their ground state. This
    entanglement is created in a relatively short time and without the
    need for further manipulation of the system. It therefore provides
    a convenient scheme to entangle two mesoscopic systems, and may
    well be useful for quantum information processing.

    Fluid acceleration in the bulk of turbulent dilute polymer solutions
    Alice M Crawford, Nicolas Mordant, Haitao Xu and Eberhard Bodenschatz
    2008 New J. Phys. 10 123015 (10pp)
    Full text PDF: http://www.iop.org/EJ/article/-alert=29894/1367-2630/10/12/123015/njp8_12_123015.pdf
    Full text HTML: http://www.iop.org/EJ/article/-alert=29894/1367-2630/10/12/123015/njp8_12_123015.html

    We studied the effects of long-chain polymers on the small scales of
    turbulence by experimental measurements of Lagrangian accelerations
    in the bulk of turbulent flows of dilute polymer solutions.
    Lagrangian accelerations were measured by following tracer
    particles with a high-speed optical tracking system. We observed a
    significant decrease in the acceleration variance in dilute polymer
    solutions as compared with in pure water. The shape of the
    normalized acceleration probability density functions, however,
    remained the same as in Newtonian water flows. We also observed an
    increase in the turbulent Lagrangian acceleration autocorrelation
    time with polymer concentration. The decrease of acceleration
    variance and the increase of acceleration autocorrelation time are
    consistent with a suppression of viscous dissipation, and cannot be
    explained by a mere increase of effective viscosity due to the

    Anomalous compressive behavior in CeO2 nanocubes under high pressure
    M Y Ge, Y Z Fang, H Wang, W Chen, Y He, E Z Liu, N H Su, K Stahl, Y P
    Feng, J S Tse, T Kikegawa, S Nakano, Z L Zhang, U Kaiser, F M Wu,
    H-K Mao and J Z Jiang
    2008 New J. Phys. 10 123016 (12pp)
    Full text PDF: http://www.iop.org/EJ/article/-alert=29894/1367-2630/10/12/123016/njp8_12_123016.pdf
    Full text HTML: http://www.iop.org/EJ/article/-alert=29894/1367-2630/10/12/123016/njp8_12_123016.html

    High-pressure angle-dispersive x-ray diffraction measurements have been
    performed on bulk and nanocrystalline cubic CeO2 with mean sizes of
    4.7 and 5.6 nm. It is found that the compressibility of the
    nanocrystals is lower than the bulk when a threshold pressure is
    reached. This critical pressure is found to be 10 GPa for 4.7 nm
    and 16 GPa for 5.6 nm CeO2 nanocubes. The particle size dependence
    of the threshold pressure for the hardening of CeO2 nanoparticles
    is quite unusual. First-principles electronic calculations show
    that the increased bulk modulus of the nanocrystal is due to the
    strengthening of the surface Ce-O bonds resulting in a much larger
    shear modulus than in the bulk and consequently hardening the shell

    Controlling molecular broadband-emission by optical confinement
    Mathias Steiner, Antonio Virgilio Failla, Achim Hartschuh, Frank
    Schleifenbaum, Clemens Stupperich and Alfred Johann Meixner
    2008 New J. Phys. 10 123017 (23pp)
    Full text PDF: http://www.iop.org/EJ/article/-alert=29894/1367-2630/10/12/123017/njp8_12_123017.pdf
    Full text HTML: http://www.iop.org/EJ/article/-alert=29894/1367-2630/10/12/123017/njp8_12_123017.html

    We investigate experimentally and theoretically the fluorescence
    emitted by molecular ensembles as well as spatially isolated,
    single molecules of an organic dye immobilized in a quasi-planar
    optical microresonator at room temperature. The optically excited
    dipole emitters couple simultaneously to on- and off-axis cavity
    resonances of the microresonator. The multi-spectral radiative
    contributions are strongly modified with respect to free
    (non-confined) space due to enhancement and inhibition of the
    molecular spontaneous emission (SpE) rate. By varying the mirror
    spacing of the microresonator on the nanometer-scale, the SpE rate
    of the cavity-confined molecules and, consequently, the spectral
    line width of the microresonator-controlled broadband fluorescence
    can be tuned by up to one order of magnitude. Stepwise reducing the
    optical confinement, we observe that the microresonator-controlled
    molecular fluorescence line shape converges towards the measured
    fluorescence line shape in free space. Our results are important
    for research on and application of broadband emitters in
    nano-optics and -photonics as well as microcavity-enhanced (single
    molecule) spectroscopy.

    Role of particle interactions in the Feshbach conversion of fermionic atoms to bosonic molecules
    Jie Liu, Li-Bin Fu, Bin Liu and Biao Wu
    2008 New J. Phys. 10 123018 (12pp)
    Full text PDF: http://www.iop.org/EJ/article/-alert=29894/1367-2630/10/12/123018/njp8_12_123018.pdf
    Full text HTML: http://www.iop.org/EJ/article/-alert=29894/1367-2630/10/12/123018/njp8_12_123018.html

    We investigate the Feshbach conversion of fermionic atom pairs to
    condensed bosonic molecules with a microscopic model that accounts
    for the repulsive interactions among all the particles involved. We
    find that the conversion efficiency is enhanced by the interaction
    between bosonic molecules, while it is suppressed by the
    interactions between fermionic atoms and between atoms and
    molecules. In the adiabatic limit, the combined effect of these
    interactions can lead to a ceiling of less than 100% on the
    conversion efficiency for a narrow Feshbach resonance. Our theory
    agrees with the recent Rice experiment on 6Li.

    Quantum-state engineering using nonlinear optical Sagnac loops

 Jun Chen, Joseph B Altepeter and Prem Kumar
    2008 New J. Phys. 10 123019 (18pp)
    Full text PDF: http://www.iop.org/EJ/article/-alert=29894/1367-2630/10/12/123019/njp8_12_123019.pdf
    Full text HTML: http://www.iop.org/EJ/article/-alert=29894/1367-2630/10/12/123019/njp8_12_123019.html

    The Kerr nonlinearity of an optical-fibre Sagnac loop can be utilized
    to engineer a variety of two-photon quantum states. These include
    correlated, identical photon pairs as well as degenerate, maximally
    entangled states - both of which are used in quantum information
    processing. In fact, their underlying principle - the reverse
    Hong-Ou-Mandel effect - can also be applied to free-space,
    down-conversion-based analogues of either identical or entangled
    photon-pair sources. Due to their simple structure, such versatile
    devices are expected to find widespread applications in
    quantum-state engineering.

    Cubic nonlinear Schro"dinger equation with vorticity
    M Caliari, M I Loffredo, L M Morato and S Zuccher
    2008 New J. Phys. 10 123020 (17pp)
    Full text PDF: http://www.iop.org/EJ/article/-alert=29894/1367-2630/10/12/123020/njp8_12_123020.pdf
    Full text HTML: http://www.iop.org/EJ/article/-alert=29894/1367-2630/10/12/123020/njp8_12_123020.html

    In this paper, we introduce a new class of nonlinear Schro"dinger
    equations (NLSEs), with an electromagnetic potential (\mathcal
    A,\Phi) , both depending on the wavefunction Ψ. The scalar
    potential Φ depends on |Ψ|2, whereas the vector potential
    \mathcal A satisfies the equation of magnetohydrodynamics with
    coefficient depending on Ψ. In Madelung variables, the velocity
    field comes to be not irrotational in general and we prove that the
    vorticity induces dissipation, until the dynamical equilibrium is
    reached. The expression of the rate of dissipation is common to all
    NLSEs in the class. We show that they are a particular case of the
    one-particle dynamics out of dynamical equilibrium for a system of
    N identical interacting Bose particles, as recently described
    within stochastic quantization by Lagrangian variational principle.
    The cubic case is discussed in particular. Results of numerical
    experiments for rotational excitations of the ground state in a
    finite two-dimensional trap with harmonic potential are reported.

    Electronic relaxation and vibrational dynamics in a thiophene oligomer
    studied under the same experimental condition with a sub-5 fs laser
    Zhuan Wang and Takayoshi Kobayashi
    2008 New J. Phys. 10 123021 (13pp)
    Full text PDF: http://www.iop.org/EJ/article/-alert=29894/1367-2630/10/12/123021/njp8_12_123021.pdf
    Full text HTML: http://www.iop.org/EJ/article/-alert=29894/1367-2630/10/12/123021/njp8_12_123021.html

    Using a sub-5 fs pulse laser, the pump-probe experiment was performed
    on a quinoid thiophene derivative and both electronic relaxation
    and vibrational dynamics were clarified with the same experimental
    data. From the data, two population decay times of the lowest
    electronic excited state were determined to be 200 fs and 1.8 ps,
    which can be explained by the assumption that the 21Ag state lies
    below the exciton 11Bu state together with the very low
    fluorescence quantum efficiency. The relaxation process after
    excitation by the pump pulse was studied to be
    11Bu→11B*u→21Ag→11Ag. According to the
    experimental data, the location of the energy level was also
    discussed. The electronic dephasing time was determined to be 64
    ± 4 fs by utilizing the data in the 'negative time' range. The
    vibrational dephasing time constant of the most strongly coupled
    mode with frequency of 1466 cm-1 was determined to be 520 ± 20
    fs from the widths of the corresponding Fourier power spectra.

    On mechanisms of interaction in electrosurgery
    Daniel Palanker, Alexander Vankov and Pradeep Jayaraman
    2008 New J. Phys. 10 123022 (15pp)
    Full text PDF: http://www.iop.org/EJ/article/-alert=29894/1367-2630/10/12/123022/njp8_12_123022.pdf
    Full text HTML: http://www.iop.org/EJ/article/-alert=29894/1367-2630/10/12/123022/njp8_12_123022.html

    Electrosurgery is broadly used in a wide variety of surgical
    procedures, yet its underlying mechanisms of interaction are poorly
    characterized. Fundamentals of electrosurgery have not changed much
    since the 1930s - cutting is still performed using continuous RF
    waveforms, leaving a collateral damage zone of hundreds of
    micrometers in depth. Pulsed waveforms with variable duty cycle are
    used mostly for tissue coagulation. Recently, we have demonstrated
    that electrosurgery with microsecond bursts applied via
    microelectrodes can provide cellular precision in soft tissue
    dissection. This paper examines dynamics of pulsed electrical
    discharges in conductive medium, and accompanying phenomena, such
    as vaporization, cavitation and ionization. It is demonstrated that
    ionization of the vapor cavity around the electrode is essential
    for energy delivery beyond the vaporization threshold. It is also
    shown that the ionization threshold voltage and resistance of the
    plasma-mediated discharge are much lower in the negative phase of
    the discharge than in the positive one. Capacitive coupling of the
    ac waveform to the electrode compensates for this asymmetry by
    shifting the medium voltage on the electrode, thus increasing the
    positive and decreasing the negative amplitudes to achieve charge
    balance in the opposite phases. With planar insulated electrodes
    having exposed edges of 12.5 um in width and bursts of 40 us in
    duration even tough biological tissues can be dissected with
    cellular precision. For example, cartilage dissection is achieved
    with pulse energy of 2.2 mJ per millimeter of length of the blade,
    and leaves a thermal damage zone of only 5-20 um in width.

    Detecting groups of similar components in complex networks
    Jiao Wang and C-H Lai
    2008 New J. Phys. 10 123023 (26pp)
    Full text PDF: http://www.iop.org/EJ/article/-alert=29894/1367-2630/10/12/123023/njp8_12_123023.pdf
    Full text HTML: http://www.iop.org/EJ/article/-alert=29894/1367-2630/10/12/123023/njp8_12_123023.html

    We study how to detect groups in a complex network each of which
    consists of component nodes sharing a similar connection pattern.
    Based on the mixture models and the exploratory analysis set up by
    Newman and Leicht (2007 Proc. Natl. Acad. Sci. USA 104 9564), we
    develop an algorithm that is applicable to a network with any
    degree distribution. The partition of a network suggested by this
    algorithm also applies to its complementary network. In general,
    groups of similar components are not necessarily identical with the
    communities in a community network; thus partitioning a network
    into groups of similar components provides additional information
    of the network structure. The proposed algorithm can also be used
    for community detection when the groups and the communities
    overlap. By introducing a tunable parameter that controls the
    involved effects of the heterogeneity, we can also investigate
    conveniently how the group structure can be coupled with the
    heterogeneity characteristics. In particular, an interesting
    example shows a group partition can evolve into a community
    partition in some situations when the involved heterogeneity
    effects are tuned. The extension of this algorithm to weighted
    networks is discussed as well.

    Controlling irreversibility and directionality of light via atomic
    motion: optical transistor and quantum velocimeter
    C H Raymond Ooi
    2008 New J. Phys. 10 123024 (17pp)
    Full text PDF: http://www.iop.org/EJ/article/-alert=29894/1367-2630/10/12/123024/njp8_12_123024.pdf
    Full text HTML: http://www.iop.org/EJ/article/-alert=29894/1367-2630/10/12/123024/njp8_12_123024.html

    The Doppler effect of moving atoms can create irreversibility of light.
    We show that the laser field in an electromagnetic induced
    transparency (EIT) scheme with atomic motion can control the
    directional propagation of two counter-propagating output probe
    fields in an atomic gas. Quantum coherence and the Doppler effect
    enable the system to function like an optical transistor with two
    outputs that can generate states analogous to the Bell basis.
    Interference of the two output fields from the gas provides useful
    features for determining the mean atomic velocity and can be used
    as a sensitive quantum velocimeter. Some subtle physics of EIT is
    also discussed. In particular, the sign of the dispersive phase in
    EIT is found to have a unique property, which helps to explain
    certain features in the interference.

    The stochastic dance of circling sperm cells: sperm chemotaxis in the plane
    B M Friedrich and F Ju"licher
    2008 New J. Phys. 10 123025 (19pp)
    Full text PDF: http://www.iop.org/EJ/article/-alert=29894/1367-2630/10/12/123025/njp8_12_123025.pdf
    Full text HTML: http://www.iop.org/EJ/article/-alert=29894/1367-2630/10/12/123025/njp8_12_123025.html

    Biological systems such as single cells must function in the presence
    of fluctuations. It has been shown in a two-dimensional
    experimental setup that sea urchin sperm cells move toward a source
    of chemoattractant along planar trochoidal swimming paths, i.e.
    drifting circles. In these experiments, a pronounced variability of
    the swimming paths is observed. We present a theoretical
    description of sperm chemotaxis in two dimensions which takes
    fluctuations into account. We derive a coarse-grained theory of
    stochastic sperm swimming paths in a concentration field of
    chemoattractant. Fluctuations enter as multiplicative noise in the
    equations for the sperm swimming path. We discuss the stochastic
    properties of sperm swimming and predict a concentration-dependence
    of the effective diffusion constant of sperm swimming which could
    be tested in experiments.

    Fundamental statistical features and self-similar properties of tagged networks
    Gergely Palla, Ille's J Farkas, Pe'ter Pollner, Imre Dere'nyi and
    Tama's Vicsek
    2008 New J. Phys. 10 123026 (20pp)
    Full text PDF: http://www.iop.org/EJ/article/-alert=29894/1367-2630/10/12/123026/njp8_12_123026.pdf
    Full text HTML: http://www.iop.org/EJ/article/-alert=29894/1367-2630/10/12/123026/njp8_12_123026.html

    We investigate the fundamental statistical features of tagged (or
    annotated) networks having a rich variety of attributes associated
    with their nodes. Tags (attributes, annotations, properties,
    features, etc) provide essential information about the entity
    represented by a given node, thus, taking them into account
    represents a significant step towards a more complete description
    of the structure of large complex systems. Our main goal here is to
    uncover the relations between the statistical properties of the
    node tags and those of the graph topology. In order to better
    characterize the networks with tagged nodes, we introduce a number
    of new notions, including tag-assortativity (relating link
    probability to node similarity), and new quantities, such as node
    uniqueness (measuring how rarely the tags of a node occur in the
    network) and tag-assortativity exponent. We apply our approach to
    three large networks representing very different domains of complex
    systems. A number of the tag related quantities display analogous
    behaviour (e.g. the networks we studied are tag-assortative,
    indicating possible universal aspects of tags versus topology),
    while some other features, such as the distribution of the node
    uniqueness, show variability from network to network allowing for
    pin-pointing large scale specific features of real-world complex
    networks. We also find that for each network the topology and the
    tag distribution are scale invariant, and this self-similar
    property of the networks can be well characterized by the
    tag-assortativity exponent, which is specific to each system.

    Evolution of the Internet and its cores
    Guo-Qing Zhang, Guo-Qiang Zhang, Qing-Feng Yang, Su-Qi Cheng and Tao
    2008 New J. Phys. 10 123027 (11pp)
    Full text PDF: http://www.iop.org/EJ/article/-alert=29894/1367-2630/10/12/123027/njp8_12_123027.pdf
    Full text HTML: http://www.iop.org/EJ/article/-alert=29894/1367-2630/10/12/123027/njp8_12_123027.html

    In this paper, we empirically study the evolution of large scale
    Internet topology at the autonomous system (AS) level. The network
    size grows in an exponential form, obeying the famous Moore's law.
    We theoretically predict that the size of the AS-level Internet
    will double every 5.32 years. We apply the k-core decomposition
    method on the real Internet, and find that the size of a k-core
    with larger k is nearly stable over time. In addition, the maximal
    coreness is very stable after 2003. In contrast to the predictions
    of most previous models, the maximal degree of the Internet is also
    relatively stable versus time. We use the edge-exchange operation
    to obtain the randomized networks with the same degree sequence. A
    systematical comparison is drawn, indicating that the real Internet
    is more loosely connected, and both the full Internet and the
    nucleus are more disassortative than their randomized versions.

    How to make large, void-free dust clusters in dusty plasma under  micro-gravity
    V Land and W J Goedheer
    2008 New J. Phys. 10 123028 (15pp)
    Full text PDF: http://www.iop.org/EJ/article/-alert=29894/1367-2630/10/12/123028/njp8_12_123028.pdf
    Full text HTML: http://www.iop.org/EJ/article/-alert=29894/1367-2630/10/12/123028/njp8_12_123028.html

    Collections of micrometer-sized solid particles immersed in plasma are
    used to mimic many systems from solid state and fluid physics, due
    to their strong electrostatic interaction, their large inertia, and
    the fact that they are large enough to be visualized with ordinary
    optics. On Earth, gravity restricts the so-called dusty plasma
    systems to thin, two-dimensional (2D) layers, unless special
    experimental geometries are used, involving heated or cooled
    electrons, and/or the use of dielectric materials. In micro-gravity
    experiments, the formation of a dust-free void breaks the isotropy
    of 3D dusty plasma systems. In order to do real 3D experiments,
    this void has somehow to be closed. In this paper, we use a fully
    self-consistent fluid model to study the closure of a void in a
    micro-gravity experiment, by lowering the driving potential. The
    analysis goes beyond the simple description of the 'virtual void',
    which describes the formation of a void without taking the dust
    into account. We show that self-organization plays an important
    role in void formation and void closure, which also allows a
    reversed scheme, where a discharge is run at low driving potentials
    and small batches of dust are added. No hysteresis is found this
    way. Finally, we compare our results with recent experiments and
    find good agreement, but only when we do not take charge-exchange
    collisions into account.

    Efficient emission of positronium negative ions from Cs deposited  W(100) surfaces
    Yasuyuki Nagashima, Toshihide Hakodate, Ayaka Miyamoto and Koji
    2008 New J. Phys. 10 123029 (7pp)
    Full text PDF: http://www.iop.org/EJ/article/-alert=29894/1367-2630/10/12/123029/njp8_12_123029.pdf
    Full text HTML: http://www.iop.org/EJ/article/-alert=29894/1367-2630/10/12/123029/njp8_12_123029.html

    The emission of positronium negative ions from Cs deposited W(100)
    surfaces has been studied. A dramatic change in the emission
    efficiency was observed upon coating a W(100) surface with Cs. The
    conversion efficiency (the fraction of incident slow positrons
    yielding the ions) of the W(100) target with a 2.2x1014 atoms cm- 2
    Cs coverage, measured over a time interval of 3x103 s immediately
    after deposition, was found to be 1.25%, which is two orders of
    magnitude higher than that obtained for the clean, uncoated W(100)
    surface and 45 times greater than the highest efficiency reported
    thus far.

    Spin state and orbital moments across the metal-insulator-transition of  REBaCo2O5.5 investigated by XMCD
    M Lafkioti, E Goering, S Gold, G Schu"tz, S N Barilo, S V Shiryaev, G L
    Bychkov, P Lemmens, V Hinkov, J Deisenhofer and A Loidl
    2008 New J. Phys. 10 123030 (9pp)
    Full text PDF: http://www.iop.org/EJ/article/-alert=29894/1367-2630/10/12/123030/njp8_12_123030.pdf
    Full text HTML: http://www.iop.org/EJ/article/-alert=29894/1367-2630/10/12/123030/njp8_12_123030.html

    DyBaCo2O5.5 has shown a complex phase diagram, which is based on the
    interplay of different energy scales, related to magnetism, orbital
    ordering and for example Co spin-state transitions. For a detailed
    understanding of these fascinating materials it is therefore
    necessary to identify the order of the different energy scales.
    Small changes in the corresponding energy relations strongly
    influence the electronic structure and ground state properties,
    like low and high spin configurations, which have been
    controversially discussed in order to interpret the
    metal-to-insulator (MIT) transition in REBaCo2O5.5 (RE = rare
    earths). To clarify unambiguously the microscopic nature of the
    spin-state evolution associated with this MIT, we performed
    detailed temperature and angular dependent x-ray magnetic circular
    dichroism measurements in DyBaCo2O5.5 single crystals above and
    below the MIT and at the onset of the ferromagnetic phase.
    Anisotropic contributions of spin and orbital moments have been
    observed with an extremely high signal-to-noise ratio. We can
    identify a higher-spin- to lower-spin-state change across the MIT,
    which is in contrast to previous macroscopic experimental findings.
    Only the Co ions in octahedral environment are found to be in a
    reduced spin configuration in the high-temperature metallic state.

    Thermodynamic properties of Ba1[?]xKxFe2As2 and Ca1[?]xNaxFe2As2
    J K Dong, L Ding, H Wang, X F Wang, T Wu, G Wu, X H Chen and S Y Li
    2008 New J. Phys. 10 123031 (7pp)
    Full text PDF: http://www.iop.org/EJ/article/-alert=29894/1367-2630/10/12/123031/njp8_12_123031.pdf
    Full text HTML: http://www.iop.org/EJ/article/-alert=29894/1367-2630/10/12/123031/njp8_12_123031.html

    The specific heat C(T) of a BaFe2As2 single crystal and hole-doped
    superconducting Ba0.5K0.5Fe2As2 and Ca0.5Na0.5Fe2As2 polycrystals
    were measured. For the undoped BaFe2As2 single crystal, a very
    sharp specific heat peak was observed at 136 K. This is attributed
    to the structural and antiferromagnetic transitions occurring at
    the same temperature. For the superconducting Ba0.5K0.5Fe2As2
    polycrystal, a clear peak of C/T was observed at Tc=36 K, which is
    the highest peak seen at a superconducting transition for
    iron-based high-Tc superconductors so far. For the superconducting
    Ca0.5Na0.5Fe2As2 sample with lower Tc=18 K, there is no obvious
    anomaly in C/T below Tc, which may be due to its low superfluid
    density. The electronic specific heat coefficients γ and
    Debye temperatures ΘD of these compounds were obtained from
    the low-temperature data.

    Barry C Sanders, Tim Senden and Volker Springel
    2008 New J. Phys. 10 125001

    Advances in physics are intimately connected with developments in a new
    technology, the telescope, precision clocks, even the computer all
    have heralded a shift in thinking. These landmark developments open
    new opportunities accelerating research and in turn new scientific
    directions. These technological drivers often correspond to new
    instruments, but equally might just as well flag a new mathematical
    tool, an algorithm or even means to visualize physics in a new way.
    Early on in this twenty-first century, scientific communities are
    just starting to explore the potential of digital visualization.
    Whether visualization is used to represent and communicate complex
    concepts, or to understand and interpret experimental data, or to
    visualize solutions to complex dynamical equations, the basic tools
    of visualization are shared in each of these applications and
    implementations. High-performance computing exemplifies the
    integration of visualization with leading research. Visualization
    is an indispensable tool for analyzing and interpreting complex
    three-dimensional dynamics as well as to diagnose numerical
    problems in intricate parallel calculation algorithms. The
    effectiveness of visualization arises by exploiting the unmatched
    capability of the human eye and visual cortex to process the large
    information content of images. In a brief glance, we recognize
    patterns or identify subtle features even in noisy data, something
    that is difficult or impossible to achieve with more traditional
    forms of data analysis. Importantly, visualizations guide the
    intuition of researchers and help to comprehend physical phenomena
    that lie far outside of direct experience. In fact, visualizations
    literally allow us to see what would otherwise remain completely
    invisible. For example, artificial imagery created to visualize the
    distribution of dark matter in the Universe has been instrumental
    to develop the notion of a cosmic web, and for helping to establish
    the current standard model of cosmology wherein this (in principle
    invisible) dark matter dominates the cosmic matter content. The
    advantages of visualization found for simulated data also hold for
    real world data as well. With the application of computerized
    acquisition many scientific disciplines are witnessing exponential
    growth rates of the volume of accumulated raw data, which often
    makes it daunting to condense the information into a manageable
    form, a challenge that can be addressed by modern visualization
    techniques. Such visualizations are also often an enticing way to
    communicate scientific results to the general public. This need for
    visualization is especially true in basic science, with its
    reliance on a benevolent and interested general public that drives
    the need for high-quality visualizations. Despite the widespread
    use of visualization, this technology has suffered from a lack of
    the unifying influence of shared common experiences. As with any
    emerging technology practitioners have often independently found
    solutions to similar problems. It is the aim of this focus issue to
    celebrate the importance of visualization, report on its growing
    use by the broad community of physicists, including biophysics,
    chemical physics, geophysics, astrophysics, and medical physics,
    and provide an opportunity for the diverse community of scientists
    using visualization to share work in one issue of a journal that
    itself is in the vanguard of supporting visualization and
    multimedia. A remarkable breadth and diversity of visualization in
    physics is to be found in this issue spanning fundamental aspects
    of relativity theory to computational fluid dynamics. The topics
    span length scales that are as small as quantum phenomena to the
    entire observable Universe. We have been impressed by the quality
    of the submissions and hope that this snap-shot will introduce,
    inform, motivate and maybe even help to unify visualization in
    physics. Readers are also directed to the December issue of Physics
    World which includes the following features highlighting work in
    this collection and other novel uses of visualization techniques:
      'A feast of visualization' Physics World December 2008
    pp 20-23   'Seeing the quantum world' by Barry Sanders
    Physics World December 2008 pp 24-27   'A picture of the
    cosmos' by Mark SubbaRao and Miguel Aragon-Calvo Physics World
    December 2008 pp 29-32   'Thinking outside the cube' by
    César A Hidalgo Physics World December 2008 pp 34-37   Focus
    on Visualization in Physics Contents Visualization of spiral and
    scroll waves in simulated and experimental cardiac tissue E M
    Cherry and F H Fenton Visualization of large scale structure from
    the Sloan Digital Sky Survey M U SubbaRao, M A Aragón-Calvo,
    H W Chen, J M Quashnock, A S Szalay and D G York How computers can
    help us in creating an intuitive access to relativity Hanns Ruder,
    Daniel Weiskopf, Hans-Peter Nollert and Thomas Müller
    Lagrangian particle tracking in three dimensions via single-camera
    in-line digital holography Jiang Lu, Jacob P Fugal, Hansen
    Nordsiek, Ewe Wei Saw, Raymond A Shaw and Weidong Yang Quantifying
    spatial heterogeneity from images Andrew E Pomerantz and Yi-Qiao
    Song Disaggregation and scientific visualization of earthscapes
    considering trends and spatial dependence structures S Grunwald
    Strength through structure: visualization and local assessment of
    the trabecular bone structure C Räth, R Monetti, J Bauer, I
    Sidorenko, D Müller, M Matsuura, E-M Lochmüller, P Zysset
    and F Eckstein Thermonuclear supernovae: a multi-scale
    astrophysical problem challenging numerical simulations and
    visualization F K Röpke and R Bruckschen Visualization needs
    and techniques for astrophysical simulations W Kapferer and T Riser
    Flow visualization and field line advection in computational fluid
    dynamics: application to magnetic fields and turbulent flows Pablo
    Mininni, Ed Lee, Alan Norton and John Clyne Splotch: visualizing
    cosmological simulations K Dolag, M Reinecke, C Gheller and S
    Imboden Visualizing a silicon quantum computer Barry C Sanders,
    Lloyd C L Hollenberg, Darran Edmundson and Andrew Edmundson
    Colliding galaxies, rotating neutron stars and merging black holes
    - visualizing high dimensional datasets on arbitrary meshes Werner
    Benger A low complexity visualization tool that helps to perform
    complex systems analysis M G Beiró, J I Alvarez-Hamelin and
    J R Busch Visualizing astrophysical N-body systems John Dubinski

    Visualizing astrophysical N-body systems
    John Dubinski
    2008 New J. Phys. 10 125002 (22pp)
    Full text PDF: http://www.iop.org/EJ/article/-alert=29894/1367-2630/10/12/125002/njp8_12_125002.pdf
    Full text HTML: http://www.iop.org/EJ/article/-alert=29894/1367-2630/10/12/125002/njp8_12_125002.html

    I begin with a brief history of N-body simulation and visualization and
    then go on to describe various methods for creating images and
    animations of modern simulations in cosmology and galactic
    dynamics. These techniques are incorporated into a specialized
    particle visualization software library called MYRIAD that is
    designed to render images within large parallel N-body simulations
    as they run. I present several case studies that explore the
    application of these methods to animations in star clusters,
    interacting galaxies and cosmological structure formation.

    A low complexity visualization tool that helps to perform complex systems analysis
    M G Beiro', J I Alvarez-Hamelin and J R Busch
    2008 New J. Phys. 10 125003 (18pp)
    Full text PDF: http://www.iop.org/EJ/article/-alert=29894/1367-2630/10/12/125003/njp8_12_125003.pdf
    Full text HTML: http://www.iop.org/EJ/article/-alert=29894/1367-2630/10/12/125003/njp8_12_125003.html

    In this paper, we present an extension of large network visualization
    (LaNet-vi), a tool to visualize large scale networks using the
    k-core decomposition. One of the new features is how vertices
    compute their angular position. While in the later version it is
    done using shell clusters, in this version we use the angular
    coordinate of vertices in higher k-shells, and arrange the highest
    shell according to a cliques decomposition. The time complexity
    goes from O(n\sqrt n) to O(n) upon bounds on a heavy-tailed degree
    distribution. The tool also performs a k-core-connectivity
    analysis, highlighting vertices that are not k-connected; e.g. this
    property is useful to measure robustness or quality of service
    (QoS) capabilities in communication networks. Finally, the actual
    version of LaNet-vi can draw labels and all the edges using
    transparencies, yielding an accurate visualization. Based on the
    obtained figure, it is possible to distinguish different sources
    and types of complex networks at a glance, in a sort of 'network

    Colliding galaxies, rotating neutron stars and merging black  holes--visualizing high dimensional datasets on arbitrary meshes
    Werner Benger
    2008 New J. Phys. 10 125004 (24pp)
    Full text PDF: http://www.iop.org/EJ/article/-alert=29894/1367-2630/10/12/125004/njp8_12_125004.pdf
    Full text HTML: http://www.iop.org/EJ/article/-alert=29894/1367-2630/10/12/125004/njp8_12_125004.html

    Visualization of datasets stemming from diverse sources is challenged
    by the large variety of substantial differences in topology,
    geometry and nature of the associated data fields. Since there is
    no standard on how to formulate and treat data for scientific
    visualization, algorithms are frequently implemented in a highly
    domain-specific way. Here, we explore the potential of point-wise
    rendering as a generic way to represent single or multiple fields
    instantaneously on arbitrary mesh types. This approach is discussed
    within the terminology of fiber bundles as a general mathematical
    concept to model scalar-, vector- and tensorfields given on
    topological spaces (with manifolds as a particular case). We give
    application examples based on datasets originating from
    astrophysics and show first results of a tensor field visualization
    of a recently produced complex dataset of colliding black holes in
    their final orbit. We finally propose a data layout representing
    the mathematical concept of a 'field' generic enough to handle all
    cases involved.

    Visualizing a silicon quantum computer
    Barry C Sanders, Lloyd C L Hollenberg, Darran Edmundson and Andrew
    2008 New J. Phys. 10 125005 (20pp)
    Full text PDF: http://www.iop.org/EJ/article/-alert=29894/1367-2630/10/12/125005/njp8_12_125005.pdf
    Full text HTML: http://www.iop.org/EJ/article/-alert=29894/1367-2630/10/12/125005/njp8_12_125005.html

    Quantum computation is a fast-growing, multi-disciplinary research
    field. The purpose of a quantum computer is to execute quantum
    algorithms that efficiently solve computational problems
    intractable within the existing paradigm of 'classical' computing
    built on bits and Boolean gates. While collaboration between
    computer scientists, physicists, chemists, engineers,
    mathematicians and others is essential to the project's success,
    traditional disciplinary boundaries can hinder progress and make
    communicating the aims of quantum computing and future technologies
    difficult. We have developed a four minute animation as a tool for
    representing, understanding and communicating a silicon-based
    solid-state quantum computer to a variety of audiences, either as a
    stand-alone animation to be used by expert presenters or embedded
    into a longer movie as short animated sequences. The paper includes
    a generally applicable recipe for successful scientific animation

    Splotch: visualizing cosmological simulations
    K Dolag, M Reinecke, C Gheller and S Imboden
    2008 New J. Phys. 10 125006 (18pp)
    Full text PDF: http://www.iop.org/EJ/article/-alert=29894/1367-2630/10/12/125006/njp8_12_125006.pdf
    Full text HTML: http://www.iop.org/EJ/article/-alert=29894/1367-2630/10/12/125006/njp8_12_125006.html

    We present a light and fast, publicly available, ray-tracer Splotch
    software tool which supports the effective visualization of
    cosmological simulations data. We describe the algorithm it relies
    on, which is designed in order to deal with point-like data,
    optimizing the ray-tracing calculation by ordering the particles as
    a function of their 'depth', defined as a function of one of the
    coordinates or other associated parameters. Realistic
    three-dimensional impressions are reached through a composition of
    the final colour in each pixel properly calculating emission and
    absorption of individual volume elements. We describe several
    scientific as well as public applications realized with Splotch. We
    emphasize how different datasets and configurations lead to
    remarkably different results in terms of the images and animations.
    A few of these results are available online.

    Flow visualization and field line advection in computational fluid dynamics: application to magnetic fields and turbulent flows
    Pablo Mininni, Ed Lee, Alan Norton and John Clyne
    2008 New J. Phys. 10 125007 (23pp)
    Full text PDF: http://www.iop.org/EJ/article/-alert=29894/1367-2630/10/12/125007/njp8_12_125007.pdf
    Full text HTML: http://www.iop.org/EJ/article/-alert=29894/1367-2630/10/12/125007/njp8_12_125007.html

    Accurately interpreting three dimensional (3D) vector quantities output
    as solutions to high-resolution computational fluid dynamics (CFD)
    simulations can be an arduous, time-consuming task. Scientific
    visualization of these fields can be a powerful aid in their
    understanding. However, numerous pitfalls present themselves
    ranging from computational performance to the challenge of
    generating insightful visual representations of the data. In this
    paper, we briefly survey current practices for visualizing 3D
    vector fields, placing particular emphasis on those data arising
    from CFD simulations of turbulence. We describe the capabilities of
    a vector field visualization system that we have implemented as
    part of an open source visual data analysis environment. We also
    describe a novel algorithm we have developed for illustrating the
    advection of one vector field by a second flow field. We
    demonstrate these techniques in the exploration of two sets of
    runs. The first comprises an ideal and a resistive
    magnetohydrodynamic (MHD) simulation. This set is used to test the
    validity of the advection scheme. The second corresponds to a
    simulation of MHD turbulence. We show the formation of structures
    in the flows, the evolution of magnetic field lines, and how field
    line advection can be used effectively to track structures therein.

    Visualization needs and techniques for astrophysical simulations
    W Kapferer and T Riser
    2008 New J. Phys. 10 125008 (15pp)
    Full text PDF: http://www.iop.org/EJ/article/-alert=29894/1367-2630/10/12/125008/njp8_12_125008.pdf
    Full text HTML: http://www.iop.org/EJ/article/-alert=29894/1367-2630/10/12/125008/njp8_12_125008.html

    Numerical simulations have evolved continuously towards being an
    important field in astrophysics, equivalent to theory and
    observation. Due to the enormous developments in computer sciences,
    both hardware- and software-architecture, state-of-the-art
    simulations produce huge amounts of raw data with increasing
    complexity. In this paper some aspects of problems in the field of
    visualization in numerical astrophysics in combination with
    possible solutions are given. Commonly used visualization packages
    along with a newly developed approach to real-time visualization,
    incorporating shader programming to uncover the computational power
    of modern graphics cards, are presented. With these techniques at
    hand, real-time visualizations help scientists to understand the
    coherences in the results of their numerical simulations.
    Furthermore a fundamental problem in data analysis, i.e. coverage
    of metadata on how a visualization was created, is highlighted.

    Thermonuclear supernovae: a multi-scale astrophysical problem challenging numerical simulations and visualization
    F K Ro"pke and R Bruckschen
    2008 New J. Phys. 10 125009 (20pp)
    Full text PDF: http://www.iop.org/EJ/article/-alert=29894/1367-2630/10/12/125009/njp8_12_125009.pdf
    Full text HTML: http://www.iop.org/EJ/article/-alert=29894/1367-2630/10/12/125009/njp8_12_125009.html

    The numerical modeling of type Ia supernovae is a demanding
    astrophysical task. Relevant physical processes take place on
    vastly different length- and timescales. This multi-scale character
    of the object poses challenges to the numerical approaches. We
    discuss an implementation that accounts for these problems by
    employing a large eddy simulation (LES) strategy for treating
    turbulence effects and a level-set technique to represent the thin
    thermonuclear flames. It is demonstrated that this approach works
    efficiently in simulations of the deflagration model and the
    delayed detonation model of type Ia supernovae. The resulting data
    reflect the multi-scale nature of the problem. Therefore,
    visualization has to be tackled with special techniques. We
    describe an approach that enables the interactive exploration of
    large datasets on commodity hardware. To this end, out-of-core
    methods are employed and the rendering of the data is achieved by a
    hybrid particle-based and texture-based volume-rendering technique.

    Strength through structure: visualization and local assessment of the  trabecular bone structure
    C Ra"th, R Monetti, J Bauer, I Sidorenko, D Mu"ller, M Matsuura, E-M
    Lochmu"ller, P Zysset and F Eckstein
    2008 New J. Phys. 10 125010 (18pp)
    Full text PDF: http://www.iop.org/EJ/article/-alert=29894/1367-2630/10/12/125010/njp8_12_125010.pdf
    Full text HTML: http://www.iop.org/EJ/article/-alert=29894/1367-2630/10/12/125010/njp8_12_125010.html

    The visualization and subsequent assessment of the inner human bone
    structures play an important role for better understanding the
    disease- or drug-induced changes of bone in the context of
    osteoporosis giving prospect for better predictions of bone
    strength and thus of the fracture risk of osteoporotic patients. In
    this work, we show how the complex trabecular bone structure can be
    visualized using uCT imaging techniques at an isotropic resolution
    of 26 um. We quantify these structures by calculating global and
    local topological and morphological measures, namely Minkowski
    functionals (MFs) and utilizing the (an-)isotropic scaling index
    method (SIM) and by deriving suitable texture measures based on MF
    and SIM. Using a sample of 151 specimens taken from human vertebrae
    in vitro, we correlate the texture measures with the mechanically
    measured maximum compressive strength (MCS), which quantifies the
    strength of the bone probe, by using Pearson's correlation
    coefficient. The structure parameters derived from the local
    measures yield good correlations with the bone strength as measured
    in mechanical tests. We investigate whether the performance of the
    texture measures depends on the MCS value by selecting different
    subsamples according to MCS. Considering the whole sample the
    results for the newly defined parameters are better than those
    obtained for the standard global histomorphometric parameters
    except for bone volume/total volume (BV/TV). If a subsample
    consisting only of weak bones is analysed, the local structural
    analysis leads to similar and even better correlations with MCS as
    compared to BV/TV. Thus, the MF and SIM yield additional
    information about the stability of the bone especially in the case
    of weak bones, which corroborates the hypothesis that the bone
    structure (and not only its mineral mass) constitutes an important
    component of bone stability.

    Disaggregation and scientific visualization of earthscapes considering  trends and spatial dependence structures
    S Grunwald
    2008 New J. Phys. 10 125011 (15pp)
    Full text PDF: http://www.iop.org/EJ/article/-alert=29894/1367-2630/10/12/125011/njp8_12_125011.pdf
    Full text HTML: http://www.iop.org/EJ/article/-alert=29894/1367-2630/10/12/125011/njp8_12_125011.html

    Earth attributes show complex, heterogeneous spatial patterns generated
    by exogenous environmental factors and formation processes. This
    study investigates various strategies to quantify the underlying
    spatial patterns of simulated fields resembling real earthscapes
    and to compare their performance for describing them. The approach
    is to disaggregate the variability of earth attributes into two
    components, deterministic trend m(xi) and spatial dependence
    ε(xi), and determine the effects of m(xi) and ε(xi)
    on prediction accuracy under various combinations of spatial fields
    of earth attributes encountered in different earthscapes. We
    illustrate that cross-dependencies exist between spatial and
    feature accuracy. Scientific visualization is used to transpose
    quantitative results into visual space.

    Quantifying spatial heterogeneity from images

 Andrew E Pomerantz and Yi-Qiao Song
    2008 New J. Phys. 10 125012 (9pp)
    Full text PDF: http://www.iop.org/EJ/article/-alert=29894/1367-2630/10/12/125012/njp8_12_125012.pdf
    Full text HTML: http://www.iop.org/EJ/article/-alert=29894/1367-2630/10/12/125012/njp8_12_125012.html

    Visualization techniques are extremely useful for characterizing
    natural materials with complex spatial structure. Although many
    powerful imaging modalities exist, simple display of the images
    often does not convey the underlying spatial structure. Instead,
    quantitative image analysis can extract the most important features
    of the imaged object in a manner that is easier to comprehend and
    to compare from sample to sample. This paper describes the
    formulation of the heterogeneity spectrum to show the extent of
    spatial heterogeneity as a function of length scale for all length
    scales to which a particular measurement is sensitive. This
    technique is especially relevant for describing materials that
    simultaneously present spatial heterogeneity at multiple length
    scales. In this paper, the heterogeneity spectrum is applied for
    the first time to images from optical microscopy. The spectrum is
    measured for thin section images of complex carbonate rock cores
    showing heterogeneity at several length scales in the range 10-10
    000 um.

    Lagrangian particle tracking in three dimensions via single-camera  in-line digital holography
    Jiang Lu, Jacob P Fugal, Hansen Nordsiek, Ewe Wei Saw, Raymond A Shaw
    and Weidong Yang
    2008 New J. Phys. 10 125013 (24pp)
    Full text PDF: http://www.iop.org/EJ/article/-alert=29894/1367-2630/10/12/125013/njp8_12_125013.pdf
    Full text HTML: http://www.iop.org/EJ/article/-alert=29894/1367-2630/10/12/125013/njp8_12_125013.html

    Lagrangian particle trajectories are measured in three spatial
    dimensions with a single camera using the method of digital in-line
    holography. Lagrangian trajectories of 60-120 um diameter droplets
    in turbulent air obtained with data from one camera compare
    favorably with tracks obtained from a simultaneous dual-camera data
    set, the latter having high spatial resolution in all three
    dimensions. Using the single-camera system, particle motion along
    the optical axis is successfully tracked, allowing for long,
    continuous 3D tracks, but the depth resolution based on standard
    reconstruction methods is not sufficient to obtain accurate
    acceleration measurements for that component. Lagrangian velocity
    distributions for all three spatial components agree within
    reasonable sampling uncertainties and Lagrangian acceleration
    distributions agree for the two lateral components. An equivalent
    single-camera, imaging-based 2D tracking system would be challenged
    by the particle densities tested, but the holographic configuration
    allows for 3D tracking in the dilute limit. The method also allows
    particle size, shape and orientation to be measured along the
    trajectory. Lagrangian measurements of particle size provide a
    direct measure of particle size uncertainty under realistic
    conditions sampled from the entire measurement volume.

    How computers can help us in creating an intuitive access to relativity
    Hanns Ruder, Daniel Weiskopf, Hans-Peter Nollert and Thomas Mu"ller
    2008 New J. Phys. 10 125014 (22pp)
    Full text PDF: http://www.iop.org/EJ/article/-alert=29894/1367-2630/10/12/125014/njp8_12_125014.pdf
    Full text HTML: http://www.iop.org/EJ/article/-alert=29894/1367-2630/10/12/125014/njp8_12_125014.html

    Computers have added many new possibilities to the tool box used for
    visualizing science in general and relativity in particular. We
    present some new results from our own work: (2+1) dimensional
    Minkowski diagrams showing two spatial dimensions, extended
    wormhole visualization, and the illustration of accretion discs by
    using the approximation via a rigidly rotating disc of dust. We
    also discuss some related examples from our earlier work, such as
    interactive and immersive visualization, or the visualization of
    the warp drive metric.

    Visualization of large scale structure from the Sloan Digital Sky  Survey
    M U SubbaRao, M A Arago'n-Calvo, H W Chen, J M Quashnock, A S Szalay
    and D G York
    2008 New J. Phys. 10 125015 (15pp)
    Full text PDF: http://www.iop.org/EJ/article/-alert=29894/1367-2630/10/12/125015/njp8_12_125015.pdf
    Full text HTML: http://www.iop.org/EJ/article/-alert=29894/1367-2630/10/12/125015/njp8_12_125015.html

    We will discuss the challenges of visualizing large cosmological
    datasets. These include observational issues such as the masks and
    incomplete nature of the survey volume, cosmological issues such as
    redshift distortions and the difficulty of visualizing datasets
    that span cosmological epochs, as well as the inherent
    visualization challenges in presenting dense three-dimensional (3D)
    datasets. Two case studies will be presented. The first will
    feature the identification of filamentary structures in the large
    scale distribution of galaxies. The second case study will feature
    visualizations of the correlations between quasar absorption line
    systems and luminous red galaxies. Finally, we will give an
    overview of our visualization work-flow which features the use of
    the open-source 3D modeling program Blender.

    Visualization of spiral and scroll waves in simulated and experimental cardiac tissue
    E M Cherry and F H Fenton
    2008 New J. Phys. 10 125016 (43pp)
    Full text PDF: http://www.iop.org/EJ/article/-alert=29894/1367-2630/10/12/125016/njp8_12_125016.pdf
    Full text HTML: http://www.iop.org/EJ/article/-alert=29894/1367-2630/10/12/125016/njp8_12_125016.html

    The heart is a nonlinear biological system that can exhibit complex
    electrical dynamics, complete with period-doubling bifurcations and
    spiral and scroll waves that can lead to fibrillatory states that
    compromise the heart's ability to contract and pump blood
    efficiently. Despite the importance of understanding the range of
    cardiac dynamics, studying how spiral and scroll waves can
    initiate, evolve, and be terminated is challenging because of the
    complicated electrophysiology and anatomy of the heart.
    Nevertheless, over the last two decades advances in experimental
    techniques have improved access to experimental data and have made
    it possible to visualize the electrical state of the heart in more
    detail than ever before. During the same time, progress in
    mathematical modeling and computational techniques has facilitated
    using simulations as a tool for investigating cardiac dynamics. In
    this paper, we present data from experimental and simulated cardiac
    tissue and discuss visualization techniques that facilitate
    understanding of the behavior of electrical spiral and scroll waves
    in the context of the heart. The paper contains many interactive
    media, including movies and interactive two- and three-dimensional
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    All mechanical mixing by means of orthogonally coupled cantilevers
    A Knoll, O Zu"ger and U Duerig
    2008 New J. Phys. 10 125017 (19pp)
    Full text PDF: http://www.iop.org/EJ/article/-alert=29894/1367-2630/10/12/125017/njp8_12_125017.pdf
    Full text HTML: http://www.iop.org/EJ/article/-alert=29894/1367-2630/10/12/125017/njp8_12_125017.html

    An all mechanical signal mixing device is described which uses only
    linear springs as fundamental building blocks. Two input
    oscillators are coupled to an orthogonally vibrating output
    oscillator via a linear spring, which results in an effective
    nonlinear multiplicative mixing function. Numerical simulations
    have been performed for studying the performance characteristics of
    the mixer. A modified version of the mixer acting as a mechanical
    modulator is also numerically investigated for application as a
    mechanical power amplifier. The viability of the concept is
    demonstrated in a centimeter scale experimental setup and a
    micromechanical scale polymer embodiment has been built using
    two-photon polymerization lithographic methods.

    Nonlinear quantum metrology using coupled nanomechanical resonators
    M J Woolley, G J Milburn and Carlton M Caves
    2008 New J. Phys. 10 125018 (13pp)
    Full text PDF: http://www.iop.org/EJ/article/-alert=29894/1367-2630/10/12/125018/njp8_12_125018.pdf
    Full text HTML: http://www.iop.org/EJ/article/-alert=29894/1367-2630/10/12/125018/njp8_12_125018.html

    We consider a nanomechanical analogue of a nonlinear interferometer,
    consisting of two parallel, flexural nanomechanical resonators,
    each with an intrinsic Duffing nonlinearity and with a switchable
    beamsplitter-like coupling between them. We calculate the precision
    with which the strength of the nonlinearity can be estimated and
    show that it scales as 1/n3/2, where n is the mean phonon number of
    the initial state. This result holds even in the presence of
    dissipation, but assumes the ability to make measurements of the
    quadrature components of the nanoresonators.

    Cluster-based density-functional approach to quantum transport through
    molecular and atomic contacts

    F Pauly, J K Viljas, U Huniar, M Ha"fner, S Wohlthat, M Bu"rkle, J C
    Cuevas and G Scho"n
    2008 New J. Phys. 10 125019 (28pp)
    Full text PDF: http://www.iop.org/EJ/article/-alert=29894/1367-2630/10/12/125019/njp8_12_125019.pdf
    Full text HTML: http://www.iop.org/EJ/article/-alert=29894/1367-2630/10/12/125019/njp8_12_125019.html

    We present a cluster-based approach to model charge transport through
    molecular and atomic contacts. The electronic structure of the
    contacts is determined in the framework of density functional
    theory, and the parameters needed to describe transport are
    extracted from finite clusters. A similar procedure, restricted to
    nearest-neighbor interactions in the electrodes, has been presented
    by Damle et al (2002 Chem. Phys. 281 171). Here, we show how to
    systematically improve the description of the electrodes by
    extracting bulk parameters from sufficiently large metal clusters.
    In this way, we avoid problems arising from the use of
    nonorthogonal basis functions. For demonstration, we apply our
    method to electron transport through Au contacts with various
    atomic-chain configurations and to a single-atom contact of Al.

    Ionization and excitation cross sections for the interaction of HZE  particles in liquid water and application to Monte Carlo simulation of radiation tracks
    Ianik Plante and Francis A Cucinotta
    2008 New J. Phys. 10 125020 (15pp)
    Full text PDF: http://www.iop.org/EJ/article/-alert=29894/1367-2630/10/12/125020/njp8_12_125020.pdf
    Full text HTML: http://www.iop.org/EJ/article/-alert=29894/1367-2630/10/12/125020/njp8_12_125020.html

    Relativistic heavy ions of high charge (Z) and energy (E) (HZE) in
    galactic cosmic rays (GCR) are important contributors to space
    radiation risk because they cannot be shielded completely and their
    relative biological effectiveness is very high. To understand these
    risks, Monte Carlo track structure simulations by radiation
    transport codes are widely used in radiation biology to provide
    information on energy deposition and production of radiolytic
    species that damage cellular structures. In this paper, we show
    that relativistic corrections can be applied to existing
    semi-empirical cross section models for the ionization and
    excitation of water molecules by ions to extend the validity of
    their energy range up to ~104 MeV amu−1. Similarly, an
    effective charge value correction is applied for Z>2 ions.
    Simulations of HZE tracks have been performed by a new C++ Monte
    Carlo transport code, named RITRACKS, that uses these cross
    sections to calculate the stopping power, radial dose, XY-plane
    projections of track segments and radial distributions of primary
    radiolytic species (H•, •OH, H2, H2O2 and e−aq) at
    ~10−12 s. These new data will be useful to understand results
    from experiments performed at ion accelerators by discriminating
    the role of the so-called core and penumbra of the tracks.

    Experimental optomechanics with silicon micromirrors
    Olivier Arcizet, Chiara Molinelli, Tristan Briant, Pierre-Franc,ois
    Cohadon, Antoine Heidmann, Jean-Marie Mackowski, Christophe Michel,
    Laurent Pinard, Olivier Franc,ais and Lionel Rousseau
    2008 New J. Phys. 10 125021 (15pp)
    Full text PDF: http://www.iop.org/EJ/article/-alert=29894/1367-2630/10/12/125021/njp8_12_125021.pdf
    Full text HTML: http://www.iop.org/EJ/article/-alert=29894/1367-2630/10/12/125021/njp8_12_125021.html

    We experimentally demonstrate the high-sensitivity optical monitoring
    of moving micromirrors, made of low-loss dielectric coatings upon
    silicon resonators of various shapes and sizes. The very high
    optical finesses obtained (\mathcal{F}\simeq 30\,000 ) have allowed
    us to measure the thermal noise of the micromirrors at room
    temperature with a shot-noise limited sensitivity at the
    10^{-19}\,{\rm m}/\sqrt{\rm Hz} level and to completely
    characterize their mechanical behavior, in excellent agreement with
    the results of a finite-element computation. Applications of such
    optomechanical systems range from quantum optics experiments to the
    experimental demonstration of the quantum ground state of a
    macroscopic mechanical resonator.

    Nanoantenna array-induced fluorescence enhancement and reduced lifetimes
    Reuben M Bakker, Vladimir P Drachev, Zhengtong Liu, Hsiao-Kuan Yuan,
    Rasmus H Pedersen, Alexandra Boltasseva, Jiji Chen, Joseph
    Irudayaraj, Alexander V Kildishev and Vladimir M Shalaev
    2008 New J. Phys. 10 125022 (16pp)
    Full text PDF: http://www.iop.org/EJ/article/-alert=29894/1367-2630/10/12/125022/njp8_12_125022.pdf
    Full text HTML: http://www.iop.org/EJ/article/-alert=29894/1367-2630/10/12/125022/njp8_12_125022.html

    Enhanced fluorescence is observed from dye molecules interacting with
    optical nanoantenna arrays. Elliptical gold dimers form individual
    nanoantennae with tunable plasmon resonances depending upon the
    geometry of the two particles and the size of the gap between them.
    A fluorescent dye, Rhodamine 800, is uniformly embedded in a
    dielectric host that coats the nanoantennae. The nanoantennae act
    to enhance the dye absorption. In turn, emission from the dye
    drives the plasmon resonance of the antennae; the nanoantennae act
    to enhance the fluorescence signal and change the angular
    distribution of emission. These effects depend upon the overlap of
    the plasmon resonance with the excitation wavelength and the
    fluorescence emission band. A decreased fluorescence lifetime is
    observed along with highly polarized emission that displays the
    characteristics of the nanoantenna's dipole mode. Being able to
    engineer the emission of the dye-nanoantenna system is important
    for future device applications in both bio-sensing and nanoscale
    optoelectronic integration.

    Classical to quantum transition of a driven nonlinear nanomechanical  resonator

    Itamar Katz, Ron Lifshitz, Alex Retzker and Raphael Straub
    2008 New J. Phys. 10 125023 (20pp)
    Full text PDF: http://www.iop.org/EJ/article/-alert=29894/1367-2630/10/12/125023/njp8_12_125023.pdf
    Full text HTML: http://www.iop.org/EJ/article/-alert=29894/1367-2630/10/12/125023/njp8_12_125023.html

    Much experimental effort is invested these days in fabricating
    nanoelectromechanical systems (NEMS) that are sufficiently small,
    cold and clean, so as to approach quantum mechanical behavior as
    their typical quantum energy scale \hbar\Omega becomes comparable
    with that of the ambient thermal energy kBT. Such systems will
    hopefully enable one to observe the quantum behavior of human-made
    objects, and test some of the basic principles of quantum
    mechanics. Here, we expand and elaborate on our recent suggestion
    (Katz et al 2007 Phys. Rev. Lett. 99 040404) to exploit the
    nonlinear nature of a nanoresonator in order to observe its
    transition into the quantum regime. We study this transition for an
    isolated resonator, as well as one that is coupled to a heat bath
    at either zero or finite temperature. We argue that by exploiting
    nonlinearities, quantum dynamics can be probed using technology
    that is almost within reach. Numerical solutions of the equations
    of motion display the first quantum corrections to classical
    dynamics that appear as the classical-to-quantum transition occurs.
    This provides practical signatures to look for in future
    experiments with NEMS resonators.

    Rapid energy transfer in a dendrimer having p-conjugated light-harvesting antennas
    I Akai, K Miyanari, T Shimamoto, A Fujii, H Nakao, A Okada, K Kanemoto,
    T Karasawa, H Hashimoto, A Ishida, A Yamada, I Katayama, J Takeda
    and M Kimura
    2008 New J. Phys. 10 125024 (22pp)
    Full text PDF: http://www.iop.org/EJ/article/-alert=29894/1367-2630/10/12/125024/njp8_12_125024.pdf
    Full text HTML: http://www.iop.org/EJ/article/-alert=29894/1367-2630/10/12/125024/njp8_12_125024.html

    We investigate rapid energy transfer (ET) and its temperature
    dependence in a star-shaped stilbenoid phthalocyanine (SSS1Pc)
    dendrimer having π-conjugated light-harvesting (LH) antennas,
    and develop an appropriate model. In SSS1Pc, an intense core
    photoluminescence (PL) band appears under the selective excitation
    of the absorption bands of the LH antenna due to highly efficient
    ET at room temperature (RT). The transient response of
    core-absorption bleaching and the temporal behaviours of the PL
    intensities of the core and antenna reveal that ET from the LH
    antenna occurs rapidly prior to achieving quasi-equilibrium in the
    photoexcited state of the LH antenna. In addition, it is also
    clarified that the ET quantum efficiency in SSS1Pc degrades at
    temperatures lower than ~100 K. To understand these results, we
    develop an ET model based on a π-conjugating network between the
    LH antenna and the core that accounts for steric hindrance between
    the LH antenna and the torsional vibration of the LH-antenna
    subunit. This model reveals that highly efficient ET occurs at RT
    through the π-conjugated network mediated by the thermally
    activated torsional vibration of the LH-antenna subunit.

    Matthias Scheffler and Wolf-Dieter Schneider
    2008 New J. Phys. 10 125025

    Basic research in surface and interface science is highly
    interdisciplinary, covering the fields of physics, chemistry,
    biophysics, geo-, atmospheric and environmental sciences, material
    science, chemical engineering, and more. The various phenomena are
    interesting by themselves, and they are most important in nearly
    all modern technologies, as for example electronic, magnetic, and
    optical devices, sensors, catalysts, lubricants, hard and
    thermal-barrier coatings, protection against corrosion and crack
    formation under harsh environments. In fact, detailed understanding
    of the elementary processes at surfaces is necessary to support and
    to advance the high technology that very much founds the prosperity
    and lifestyle of our society. Current state-of-the-art experimental
    studies of elementary processes at surfaces, of surface properties
    and functions employ a variety of sophisticated tools. Some are
    capable of revealing the location and motion of individual atoms.
    Others measure excitations (electronic, magnetic and vibronic),
    employing, for example, special light sources such as synchrotrons,
    high magnetic fields, or free electron lasers. The surprising
    variety of intriguing physical phenomena at surfaces, interfaces,
    and nanostructures also pose a persistent challenge for the
    development of theoretical descriptions, methods, and even basic
    physical concepts. This second focus issue on the topic of
    'Advances in Surface and Interface Science' in New Journal of
    Physics, following on from last year's successful collection,
    provides an exciting synoptic view on the latest pertinent
    developments in the field. Focus on Advances in Surface and
    Interface Science 2008 Contents Organic layers at metal/electrolyte
    interfaces: molecular structure and reactivity of viologen
    monolayers Stephan Breuer, Duc T Pham, Sascha Huemann, Knud Gentz,
    Caroline Zoerlein, Ralf Hunger, Klaus Wandelt and Peter Broekmann
    Spin polarized d surface resonance state of fcc Co/Cu(001) K
    Miyamoto, K Iori, K Sakamoto, H Narita, A Kimura, M Taniguchi, S
    Qiao, K Hasegawa, K Shimada, H Namatame and S Blügel Activated
    associative desorption of C + O → CO from Ru(001) induced by
    femtosecond laser pulses S Wagner, H Öström, A Kaebe, M
    Krenz, M Wolf, A C Luntz and C Frischkorn Surface structure of
    Sn-doped In2O3 (111) thin films by STM Erie H Morales, Yunbin He,
    Mykola Vinnichenko, Bernard Delley and Ulrike Diebold Coulomb
    oscillations in three-layer graphene nanostructures J
    Güttinger, C Stampfer, F Molitor, D Graf, T Ihn and K Ensslin
    Adsorption processes of hydrogen molecules on SiC(001), Si(001) and
    C(001) surfaces Xiangyang Peng, Peter Krüger and Johannes
    Pollmann Fermi surface nesting in several transition metal
    dichalcogenides D S Inosov, V B Zabolotnyy, D V Evtushinsky, A A
    Kordyuk, B Büchner, R Follath, H Berger and S V Borisenko
    Probing molecule-surface interactions through ultra-fast adsorbate
    dynamics: propane/Pt(111) A P Jardine, H Hedgeland, D Ward, Y
    Xiaoqing, W Allison, J Ellis and G Alexandrowicz A novel method
    achieving ultra-high geometrical resolution in scanning tunnelling
    microscopy R Temirov, S Soubatch, O Neucheva, A C Lassise and F S

    Probing molecule-surface interactions through ultra-fast adsorbate dynamics:propane/Pt(111)
    A P Jardine, H Hedgeland, D Ward, Y Xiaoqing, W Allison, J Ellis and G
    2008 New J. Phys. 10 125026 (20pp)
    Full text PDF: http://www.iop.org/EJ/article/-alert=29894/1367-2630/10/12/125026/njp8_12_125026.pdf
    Full text HTML: http://www.iop.org/EJ/article/-alert=29894/1367-2630/10/12/125026/njp8_12_125026.html

    3He spin echo measurements of the atomic scale motion of propane on a
    Pt(111) surface are presented. The measurements provide both the
    height of the energy barriers to diffusion and the strength of the
    frictional coupling of propane to the substrate. We show that both
    the rate and the nature of the dynamics we measure cannot be
    reproduced by an existing empirical potential. Using numerical
    simulation we derive a potential energy surface which is capable of
    reproducing the main features of our dataset.

    Fermi surface nesting in several transition metal dichalcogenides
    D S Inosov, V B Zabolotnyy, D V Evtushinsky, A A Kordyuk, B Bu"chner, R
    Follath, H Berger and S V Borisenko
    2008 New J. Phys. 10 125027 (10pp)
    Full text PDF: http://www.iop.org/EJ/article/-alert=29894/1367-2630/10/12/125027/njp8_12_125027.pdf
    Full text HTML: http://www.iop.org/EJ/article/-alert=29894/1367-2630/10/12/125027/njp8_12_125027.html

    By means of high-resolution angle-resolved photoelectron spectroscopy
    (ARPES), we have studied the fermiology of 2H transition metal
    dichalcogenide polytypes TaSe2, NbSe2 and Cu0.2NbS2. The
    tight-binding model of the electronic structure, extracted from
    ARPES spectra for all three compounds, was used to calculate the
    Lindhard function (bare spin susceptibility), which reflects the
    propensity to charge density wave (CDW) instabilities observed in
    TaSe2 and NbSe2. We show that though the Fermi surfaces of all
    three compounds possess an incommensurate nesting vector in the
    close vicinity of the CDW wave vector, the nesting and ordering
    wave vectors do not exactly coincide, and there is no direct
    relationship between the magnitude of the susceptibility at the
    nesting vector and the CDW transition temperature. The nesting
    vector persists across the incommensurate CDW transition in TaSe2
    as a function of temperature despite the observable variations of
    the Fermi surface geometry in this temperature range. In Cu0.2NbS2,
    the nesting vector is present despite different doping levels,
    which leads us to expect a possible enhancement of the CDW
    instability with Cu intercalation in the CuxNbS2 family of

    Adsorption processes of hydrogen molecules on SiC(001), Si(001) and  C(001) surfaces
    Xiangyang Peng, Peter Kru"ger and Johannes Pollmann
    2008 New J. Phys. 10 125028 (19pp)
    Full text PDF: http://www.iop.org/EJ/article/-alert=29894/1367-2630/10/12/125028/njp8_12_125028.pdf
    Full text HTML: http://www.iop.org/EJ/article/-alert=29894/1367-2630/10/12/125028/njp8_12_125028.html

    Adsorption processes of hydrogen molecules on the Si(001)-(2x1) and
    C(001)-(2x1) surfaces are discussed in light of our previous
    studies of H2 adsorption on the related SiC(001)-c(4x2) surface.
    Very amazingly, there are pathways above the latter on which
    hydrogen molecules can adsorb dissociatively at room temperature.
    One of these pathways has not been considered before for adsorption
    of H2 on the Si(001)-(2x1) or C(001)-(2x1) surface. Therefore, we
    report first-principles investigations of the reaction of molecular
    hydrogen with the Si(001)-(2x1) and C(001)-(2x1) surfaces on this
    new adsorption pathway in addition to those that have been studied
    before. In spite of a number of similarities, the three surfaces
    show distinct differences as well, giving rise to spectacularly
    different reactivities with hydrogen molecules. This is due to the
    fact that the reaction of H2 with semiconductor surfaces depends
    crucially on intricate combined effects of the arrangement of
    surface dimers, as well as the orientation of their dangling bond
    orbitals. In addition, the chemical nature of the surface atoms has
    a pronounced effect on the spatial extent of dangling bond orbitals
    which influences the adsorption behaviour markedly as well. In
    agreement with experiments, our results show that Si(001)-(2x1) and
    C(001)-(2x1) are inert to H2 adsorption at room temperature for all
    investigated pathways which exhibit substantial energy barriers.
    For the two reaction pathways that have been investigated before,
    our results are in good accord with those of previous density
    functional and quantum Monte Carlo (QMC) calculations. As a matter
    of fact, the new reaction channel studied in this work for the
    first time turns out to have the lowest energy barrier for H2
    adsorption on the diamond surface and should thus be the most
    important channel for sticking of H2 on C(001)-(2x1).

    Coulomb oscillations in three-layer graphene nanostructures
    J Gu"ttinger, C Stampfer, F Molitor, D Graf, T Ihn and K Ensslin
    2008 New J. Phys. 10 125029 (10pp)
    Full text PDF: http://www.iop.org/EJ/article/-alert=29894/1367-2630/10/12/125029/njp8_12_125029.pdf
    Full text HTML: http://www.iop.org/EJ/article/-alert=29894/1367-2630/10/12/125029/njp8_12_125029.html

    We present transport measurements on a tunable three-layer graphene
    single electron transistor (SET). The device consists of an etched
    three-layer graphene flake with two narrow constrictions separating
    the island from source and drain contacts. Three lateral graphene
    gates are used to electrostatically tune the device. An individual
    three-layer graphene constriction has been investigated separately
    showing a transport gap near the charge neutrality point. The
    graphene tunneling barriers show a strongly nonmonotonic coupling
    as a function of gate voltage indicating the presence of localized
    states in the constrictions. We show Coulomb oscillations and
    Coulomb diamond measurements proving the functionality of the
    graphene SET. A charging energy of ≈0.6 meV is extracted.

    Surface structure of Sn-doped In2O3 (111) thin films by STM
    Erie H Morales, Yunbin He, Mykola Vinnichenko, Bernard Delley and
    Ulrike Diebold
    2008 New J. Phys. 10 125030 (11pp)
    Full text PDF: http://www.iop.org/EJ/article/-alert=29894/1367-2630/10/12/125030/njp8_12_125030.pdf
    Full text HTML: http://www.iop.org/EJ/article/-alert=29894/1367-2630/10/12/125030/njp8_12_125030.html

    High-quality Sn-doped In2O3 (ITO) films were grown epitaxially on
    yttria stabilized zirconia (111) with oxygen-plasma assisted
    molecular beam epitaxy (MBE). The 12 nm thick films, containing
    2-6% Sn, are fully oxidized. Angle-resolved x-ray photoelectron
    spectroscopy (ARXPS) confirms that the Sn dopant substitutes In
    atoms in the bixbyite lattice. From XPS peak shape analysis and
    spectroscopic ellipsometry measurements it is estimated that, in a
    film with 6 at.% Sn, ~1/3 of the Sn atoms are electrically active.
    Reflection high energy electron diffraction (RHEED) shows a flat
    surface morphology and scanning tunneling microscopy (STM) shows
    terraces several hundred nanometers in width. The terraces consist
    of 10 nm wide orientational domains, which are attributed to the
    initial nucleation of the film. Low energy electron diffraction
    (LEED) and STM results show a bulk-terminated (1 x 1) surface,
    which is supported by first-principles density functional theory
    (DFT) calculations. Atomically resolved STM images are consistent
    with Tersoff-Hamann calculations that show that surface In atoms
    are imaged bright or dark, depending on the configuration of their
    O neighbors. The coordination of surface atoms on the
    In2O3(111)-1x1 surface is analyzed in terms of their possible role
    in surface chemical reactions.

    Activated associative desorption of C + O - CO from Ru(001) induced by   femtosecond laser pulses
    S Wagner, H O"stro"m, A Kaebe, M Krenz, M Wolf, A C Luntz and C
    2008 New J. Phys. 10 125031 (24pp)
    Full text PDF: http://www.iop.org/EJ/article/-alert=29894/1367-2630/10/12/125031/njp8_12_125031.pdf
    Full text HTML: http://www.iop.org/EJ/article/-alert=29894/1367-2630/10/12/125031/njp8_12_125031.html

    The femtosecond (fs)-laser-induced associative desorption of CO from a
    C/O coadsorbate on Ru(001) has been investigated. The recombination
    of the atomic reactants is found to originate predominantly from
    oxidation of isolated 'reactive' carbon atoms, whereas oxidation of
    surface carbon with carbon-carbon bonds is not observed. Due to the
    excess of oxygen atoms (C coverage in the few-percent range) the
    Cads + Oads → COgas formation exhibits first-order kinetics.
    For both excitation wavelengths 400 and 800 nm, a strongly
    nonlinear fluence (F) dependence of the CO desorption yield Y is
    observed with exponents n≈4 in a power law parametrization
    Y∝⟨F⟩n. Furthermore, excitation with 400 nm pulses
    leads to a significantly higher desorption yield as compared to 800
    nm laser light with cross sections and desorption probabilities for
    400 and 800 nm excitation of σeff=4.9x10−18 cm2,
    Pdes=0.17 and σeff=1.1x10−18 cm2, Pdes=0.07,
    respectively, at an absorbed fluence of ⟨F⟩=170 J
    m−2. This wavelength dependence is attributed to the shorter
    optical penetration of 400 nm light in the Ru substrate leading to
    higher surface temperatures at the same absorbed energy rather than
    to nonthermalized hot electrons. In addition, two-pulse-correlation
    measurements show a full-width at half-maximum of ~ 20 ps excluding
    a purely electron-driven reaction mechanism, which should exhibit a
    subpicosecond response time. However, careful qualitative and
    quantitative analyses based on frictional modelling of the
    adsorbate-substrate coupling reveals that the C-O association
    reaction is mediated by both substrate phonons and electrons. The
    electronic, i.e. nonadiabatic contribution with a coupling constant
    of ηel=1/500 fs−1 is responsible for the ultrafast
    activation of the reaction found in the frictional modelling to  occur within ~1 ps after excitation. Similarities to the
    associative desorption of N2 (isoelectronic with CO) from
    N/Ru(001), a system for which density-functional calculations
    exist, can be drawn. Finally, the energy transfer to nuclear
    degrees of freedom during the C-O association process on the
    Ru(001) surface has been studied with time-of-flight measurements.
    The obtained translational energies expressed by
    Ttrans=⟨Etrans⟩/2kB≈700 K exhibit only a weak
    dependence on the absorbed laser fluence and are by a factor of ~3
    lower than the calculated surface temperatures present after
    fs-laser excitation. Possible origins of this discrepancy, such as
    unequal energy partitioning between the molecular degrees of
    freedom or nonadiabatic damping, are discussed.

    Spin polarized d surface resonance state of fcc Co/Cu(001)
    K Miyamoto, K Iori, K Sakamoto, H Narita, A Kimura, M Taniguchi, S
    Qiao, K Hasegawa, K Shimada, H Namatame and S Blu"gel
    2008 New J. Phys. 10 125032 (10pp)
    Full text PDF: http://www.iop.org/EJ/article/-alert=29894/1367-2630/10/12/125032/njp8_12_125032.pdf
    Full text HTML: http://www.iop.org/EJ/article/-alert=29894/1367-2630/10/12/125032/njp8_12_125032.html

    Spin- and angle-resolved photoemission spectroscopy has been applied to
    the study of the surface and bulk electronic structures of a
    face-centered cubic (fcc) Co thin film. We have experimentally
    resolved a negatively spin-polarized surface resonance state of fcc
    Co/Cu(001) at 0.4 eV below the Fermi energy. Moreover, we have
    found that the surface resonance state exhibits a strong spin-orbit
    interaction through an investigation of magnetic dichroism in the
    angular distribution spectrum of Co/Cu(001).

    Organic layers at metal/electrolyte interfaces: molecular structure and reactivity of viologen monolayers
    Stephan Breuer, Duc T Pham, Sascha Huemann, Knud Gentz, Caroline
    Zoerlein, Ralf Hunger, Klaus Wandelt and Peter Broekmann
    2008 New J. Phys. 10 125033 (24pp)
    Full text PDF: http://www.iop.org/EJ/article/-alert=29894/1367-2630/10/12/125033/njp8_12_125033.pdf
    Full text HTML: http://www.iop.org/EJ/article/-alert=29894/1367-2630/10/12/125033/njp8_12_125033.html

    The adsorption of viologens (1,1'-disubstituted-4,4'-bipyridinium
    molecules) on a chloride-modified copper electrode has been studied
    using a combination of cyclic voltammetry (CV), in-situ scanning
    tunneling microscopy (STM) and ex-situ photoemission spectroscopy
    (XPS). Two prototypes of viologens could be identified with respect
    to their redox behavior upon adsorption, namely those which retain
    (non-reactive adsorption) and those which change their redox state
    (reactive adsorption) upon interaction with the chloride-modified
    copper surface at given potential. The first class of viologens
    represented by 1,1'-dibenzyl-4,4'-bipyridinium molecules
    (dibenzyl-viologens, abbreviated as DBV) can be adsorbed and
    stabilized on this electrode surface in their di-cationic state at
    potentials more positive than the reduction potential of the
    solution species. XPS N1s core level shifts verify that the
    adsorbed DBV molecules on the electrode are in their oxidized
    di-cationic state. Electrostatic attraction between the partially
    solvated viologen di-cations and the anionic chloride layer is
    discussed as the main driving force for the DBV stabilization on
    the electrode surface. Analysis of the N1s and O1s core level
    shifts points to a non-reactive DBV adsorption leaving the DBVads2+
    solvation shell partly intact. The laterally ordered DBVads2+
    monolayer turns out to be hydrophilic with at least four water
    molecules per viologen present within this cationic organic film.
    The analysis of the Cl2p core level reveals that no further
    chloride species are present at the surface besides those which are
    specifically adsorbed, i.e. which are in direct contact with the
    metallic copper surface underneath the organic layer. The reduction
    of these adsorbed DBVads2+ surface species takes place only in the
    same potential regime where the solvated DBVaq2+ bulk solution
    species react and is accompanied by a pronounced structural change
    from the di-cationic 'cavitand'-structure to a 'stripe'-structure
    of chains of π-stacked DBV•+ mono-cation radicals as
    verified by in-situ STM. The second class of viologens represented
    by 1,1'-diphenyl-4,4'-bipyridinium molecules (diphenyl-viologens,
    abbreviated as DPV) is much more reactive upon adsorption and
    cannot be stabilized on the electrode surface in a di-cationic
    state, at least within the narrow potential window of copper. The
    N1s core level binding energy indicates only the presence of the
    corresponding mono-reduced DPVads•+ species on the surface
    even at potentials more positive than the redox potential of the
    bulk solution species. This process leads to the formation of a
    hydrophobic viologen monolayer with stacked polymeric
    \left({{\rm{DPV}}_{{\rm{ads}}}^{ \bullet + } } \right)_n chains as
    the characteristic structural motif. The wet electrochemical
    reduction of viologens is further compared with a dry reduction
    under UHV conditions. The latter reaction inevitably affects the
    di-cationic viologen species in the course of the photoemission
    experiment. Slow photoelectrons and secondary electrons are assumed
    to transform the di-cationic viologens into the corresponding
    radical mono-cations upon irradiation.

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Since 1962 I doubted on Newton's laws. I did not accept the infinitive speed and I found un-vivid the laws of gravity and time.

I learned the Einstein's Relativity, thus I found some answers for my questions. But, I had another doubt of Infinitive Mass-Energy. And I wanted to know why light has stable speed?




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