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.

Dynamic Diffraction and Interband Transitions in Two-Dimensional Photonic Lattices

Abstract: We reveal a direct link between two fundamental wave phenomena in periodic media, Pendell\"osung oscillations and resonant coupling between spectral bands. We experimentally measure the power transfer between laser beams associated with the high-symmetry points in periodic and biased hexagonal photonic lattices. As a result, we demonstrate that Pendell\"osung oscillations dominate the dynamics of resonant interband transitions on a short propagation scale.

Spin-domain formation in antiferromagnetic condensates

Abstract: Antiferromagnetic condensates are generally believed not to display modulational instability and subsequent spin-domain formation. Here we demonstrate that in the presence of a homogeneous magnetic field antiferromagnetic spin-1 Bose-Einstein condensates can undergo spatial modulational instability followed by the subsequent generation of spin domains. Employing numerical simulations for realistic conditions, we show how this effect can be observed in sodium condensates confined in an optical trap. Finally, we link this instability and spin-domain formation with stationary modes of the condensate.

Interaction of matter-wave gap solitons in optical lattices

Abstract: We study the mobility and interaction of gap solitons in a Bose–Einstein condensate (BEC) confined by an optical lattice potential. Such localized wavepackets can exist only in the gaps of the matter-wave band-gap spectrum and their interaction properties are shown to serve as a measure of the discreteness imposed on a BEC by the lattice potential. We show that inelastic collisions of two weakly localized near-band-edge gap solitons provide a simple and effective means for generating strongly localized in-gap solitons through soliton fusion.

Symmetry-breaking instabilities of spatial parametric solitons

Abstract: For three decades optical spatial solitons confined in the transverse plane were commonly believed to be a prerogative of media with cubiclike nonlinearities @1#. A remarkable exception is the work carried out in Ref. @2#, where the possibility to achieve diffraction-free propagation via threephoton interactions in quadratic media ~henceforth, parametric solitons! was first pointed out. The field of quadratic solitons has acquired importance only recently @3#, also stimulated by experiments in second-harmonic generation ~SHG! in bulk media ~211 dimensions! and planar waveguides ~111 dimensions! @4#. Since the parametric solitons are strictly speaking solitary waves ~the model equations are not integrable!, a crucial issue is their stability. Two main types of instabilities can be distinguished: ~i! longitudinal instability against perturbations that share the soliton symmetry @5#; ~ii! symmetrybreaking instabilities ~reminiscent of modulational instabilities of plane-waves @6#!, that take place whenever the solitons are embedded in a higher dimensional ‘‘space’’ with respect to the subspace in which they are localized @7,8#. For the former type of problem, stability criteria have been recently developed @5#, through asymptotic techniques @9#: both ~111!and ~211!-dimensional parametric solitons are stable in the largest portion of their existence domain in the parameter space. Moreover, the global stability ~no collapse! of ~211!and ~311!-dimensional parametric solitons and bullets is supported by the Liapunov-type stability analysis @10#. Conversely, the symmetry breaking of parametric solitons is still an open issue, even though the problem has been widely studied for cubic media @7#. Here we investigate the stability of the whole one-parameter families of ground-state planar SHG solitons. We anticipate that the development of the instability leads either to the formation of lattices of higher dimensional solitons, or to the complete disintegration ~radiative decay! of the soliton. The transverse instability of soliton stripes belongs to the former case, whereas the dynamics of temporal instabilities of both ~111!and ~211!dimensional solitons depends on the dispersive regime. Our results are of great importance for recent experiments in transverse pattern formation occurring via SHG @11,12#. In particular, the filamentation of beams with strongly elliptical cross sections ~i.e., pseudostripe! was already observed @11#, using nonsoliton input conditions ~i.e., SHG from the funda-

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。