Yuri S. Kivshar

Bio: Yuri S. Kivshar is an academic researcher from Australian National University. The author has contributed to research in topics: Metamaterial & Soliton. The author has an hindex of 126, co-authored 1845 publications receiving 79415 citations. Previous affiliations of Yuri S. Kivshar include Technische Universität Darmstadt & Los Alamos National Laboratory.

Spatiotemporal surface solitons in two-dimensional photonic lattices.

Abstract: We analyze spatiotemporal light localization in truncated two-dimensional photonic lattices and demonstrate the existence of two-dimensional surface light bullets localized in the lattice corners or the edges. We study the families of the spatiotemporal surface solitons and their properties such as bistability and compare them with the modes located deep inside the photonic lattice.

Tunable positive and negative refraction in optically induced photonic lattices.

Abstract: We study tunable refraction of light in one-dimensional periodic lattices induced optically in a photorefractive crystal. We observe experimentally both positive and negative refraction of beams that selectively excite the first or second spectral bands of the periodic lattice, and we demonstrate tunability of the output beam position by dynamically adjusting the lattice depth. At higher laser intensities, beam broadening due to diffraction can be suppressed through nonlinear self-focusing while preserving the general steering properties.

Electric current induced unidirectional propagation of surface plasmon-polaritons

Abstract: Nonreciprocity and one-way propagation of optical signals is crucial for modern nanophotonic technology, and is typically achieved using magneto-optical effects requiring large magnetic biases. Here we suggest a fundamentally novel approach to achieve unidirectional propagation of surface plasmon-polaritons (SPPs) at metal-dielectric interfaces. We employ a direct electric current in metals, which produces a Doppler frequency shift of SPPs due to the uniform drift of electrons. This tilts the SPP dispersion, enabling one-way propagation, as well as zero and negative group velocities. The results are demonstrated for planar interfaces and cylindrical nanowire waveguides.

Gap solitons due to cascading

Abstract: It is shown analytically that gap solitons can occur in materials with ${\mathrm{\ensuremath{\chi}}}^{(2)}$ susceptibility due to cascaded second-order nonlinearities. Families of bright and dard spatial gap solitons are described in the framework of asymptotic expansions that are valid, in particular, for nonzero phase mismatch between the first and second harmonics; effective coefficients of self- and cross-phase modulation are calculated.

Kink’s internal modes in the Frenkel-Kontorova model

Abstract: We consider a generalized Frenkel-Kontorova model, describing the dynamics of a chain of particles in a periodic substrate potential, and analyze the effect of discreteness on the existence and properties of internal ~or shape! modes of kinks, topological excitations of the chain. In particular, we show that kink’s internal modes can appear not only below but also above the phonon spectrum band and, in the latter case, the localized mode describes out-of-phase oscillations of the kink’s shape. For the sinusoidal on-site potential, when the model is described by the discrete sine-Gordon equation, we reveal, in sharp contrast with the continuum limit, the existence of the kink’s internal mode in a narrow region of the discreteness parameter. We apply two different analytical techniques to describe the cases of weak and strong coupling between particles, explaining qualitatively and even quantitatively the main features of the kink oscillations observed in numerical simulations. We also discuss the effect of nonlinearity on the existence and properties of kink’s internal modes and show, in particular, that a nonlinearity-induced frequency shift of the lattice vibrations can lead to the creation of the nonlinear kink’s internal modes, which, however, slowly decay due to a generation of radiation through higher-order harmonics. @S1063-651X~97!11010-8#

I and i

Abstract: There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality. Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

Fast parallel algorithms for short-range molecular dynamics

Abstract: Three parallel algorithms for classical molecular dynamics are presented. The first assigns each processor a fixed subset of atoms; the second assigns each a fixed subset of inter-atomic forces to compute; the third assigns each a fixed spatial region. The algorithms are suitable for molecular dynamics models which can be difficult to parallelize efficiently—those with short-range forces where the neighbors of each atom change rapidly. They can be implemented on any distributed-memory parallel machine which allows for message-passing of data between independently executing processors. The algorithms are tested on a standard Lennard-Jones benchmark problem for system sizes ranging from 500 to 100,000,000 atoms on several parallel supercomputers--the nCUBE 2, Intel iPSC/860 and Paragon, and Cray T3D. Comparing the results to the fastest reported vectorized Cray Y-MP and C90 algorithm shows that the current generation of parallel machines is competitive with conventional vector supercomputers even for small problems. For large problems, the spatial algorithm achieves parallel efficiencies of 90% and a 1840-node Intel Paragon performs up to 165 faster than a single Cray C9O processor. Trade-offs between the three algorithms and guidelines for adapting them to more complex molecular dynamics simulations are also discussed.

疟原虫var基因转换速率变化导致抗原变异[英]／Paul H, Robert P, Christodoulou Z, et al//Proc Natl Acad Sci U S A

Abstract: 抗原变异可使得多种致病微生物易于逃避宿主免疫应答。表达在感染红细胞表面的恶性疟原虫红细胞表面蛋白1（PfPMP1）与感染红细胞、内皮细胞、树突状细胞以及胎盘的单个或多个受体作用，在黏附及免疫逃避中起关键的作用。每个单倍体基因组var基因家族编码约60种成员，通过启动转录不同的var基因变异体为抗原变异提供了分子基础。