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.

Soliton-based optical switching in waveguide arrays

Abstract: We analyze the propagation of discrete solitons in a periodic system of weakly coupled nonlinear optical waveguides, i.e., a waveguide array. Soliton reflection, transmission, and trapping, as well as coherent and incoherent interaction with a linear guided wave [which can exist owing to defect (inhomogeneous) coupling between two neighboring waveguides], are demonstrated numerically and investigated analytically with a collective-coordinate approach. Some potential schemes of controllable and steerable soliton-based optical switching in nonlinear waveguide arrays are discussed. For the first scheme it is suggested that unstable soliton modes be used to achieve easily steerable propagation of discrete bright and dark solitons. This is to avoid mode trapping by the effective Peierls –Nabarro potential, which always appears because of the system discreteness. The other scheme is based on soliton control with the help of a linear guided wave that can be excited in an inhomogeneous array.

Matter-wave gap solitons in atomic band-gap structures.

Abstract: We demonstrate that a Bose-Einstein condensate in an optical lattice forms a reconfigurable matter-wave structure with a band-gap spectrum, which resembles a nonlinear photonic crystal for light waves. We study in detail the case of a two-dimensional square optical lattice and show that this atomic band-gap structure allows nonlinear localization of atomic Bloch waves in the form of two-dimensional matter-wave gap solitons.

Efficient Second-Harmonic Generation in Nanocrystalline Silicon Nanoparticles

Abstract: Recent trends to employ high-index dielectric particles in nanophotonics are motivated by their reduced dissipative losses and large resonant enhancement of nonlinear effects at the nanoscale. Because silicon is a centrosymmetric material, the studies of nonlinear optical properties of silicon nanoparticles have been targeting primarily the third-harmonic generation effects. Here we demonstrate, both experimentally and theoretically, that resonantly excited nanocrystalline silicon nanoparticles fabricated by an optimized laser printing technique can exhibit strong second-harmonic generation (SHG) effects. We attribute an unexpectedly high yield of the nonlinear conversion to a nanocrystalline structure of nanoparticles supporting the Mie resonances. The demonstrated efficient SHG at green light from a single silicon nanoparticle is 2 orders of magnitude higher than that from unstructured silicon films. This efficiency is significantly higher than that of many plasmonic nanostructures and small silicon nan...

Internal Modes of Solitary Waves

Abstract: We develop an analytical approach for describing a birth of internal modes of solitary waves in nonintegrable nonlinear models We show that a small perturbation of a proper sign to an integrable model can create a soliton internal mode bifurcating from the continuous wave spectrum The theory is applied to the double sine-Gordon and discrete nonlinear Schrodinger equations, and an excellent agreement with numerical data is demonstrated [S0031-9007(98)06329-7]

Tunable transmission and harmonic generation in nonlinear metamaterials

Abstract: We study the properties of a tunable nonlinear metamaterial operating at microwave frequencies We fabricate the nonlinear metamaterial composed of double split-ring resonators and wires where a varactor diode is introduced into each resonator so that the magnetic resonance can be tuned dynamically by varying the input power We show that at higher powers the transmission of the metamaterial becomes power dependent, and we demonstrate experimentally power-dependent transmission properties and selective generation of higher harmonics

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。