Ultrafast magnetic vortex core switching driven by topological inverse Faraday effect

We present a theoretical discovery of an unconventional mechanism of inverse Faraday effect (IFE) which acts selectively on topological magnetic structures. The effect, topological inverse Faraday effect (TIFE), is induced by spin Berry's phase of the magnetic structure when a circularly polarized light is applied. Thus a spin-orbit interaction is not necessary unlike in the conventional IFE. We demonstrate by numerical simulation that TIFE realizes ultrafast switching of a magnetic vortex within a switching time of 150 ps without magnetic field.Comment: 11 pages, 4 figure

Mesoscopic Hall effect driven by chiral spin order

A Hall effect due to spin chirality in mesoscopic systems is predicted. We consider a 4-terminal Hall system including local spins with geometry of a vortex domain wall, where strong spin chirality appears near the center of vortex. The Fermi energy of the conduction electrons is assumed to be comparable to the exchange coupling energy where the adiabatic approximation ceases to be valid. Our results show a Hall effect where a voltage drop and a spin current arise in the transverse direction. The similarity between this Hall effect and the conventional spin Hall effect in systems with spin-orbit interaction is pointed out.Comment: 4 pages, 4 figure

Specifying and verifying sensor networks: An experiment of formal methods

10.1007/978-3-540-88194-0-20Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics)5256 LNCS318-33

Inference of Gene Regulation via miRNAs During ES Cell Differentiation Using MiRaGE Method

MicroRNA (miRNA) is a critical regulator of cell growth, differentiation, and development. To identify important miRNAs in a biological process, many bioinformatical tools have been developed. We have developed MiRaGE (MiRNA Ranking by Gene Expression) method to infer the regulation of gene expression by miRNAs from changes of gene expression profiles. The method does not require precedent array normalization. We applied the method to elucidate possibly important miRNAs during embryonic stem (ES) cell differentiation to neuronal cells and we infer that certain miRNAs, including miR-200 family, miR-429, miR-302 family, and miR-17-92 cluster members may be important to the maintenance of undifferentiated status in ES cells

Pressurization facilitates adenovirus-mediated gene transfer into vein graft

AbstractWe investigated whether application of non-distending hydrostatic pressure facilitates gene transfer into vein grafts. An external jugular vein was placed in a chamber with 100 μl adenovirus solution at a titer of 1010 pfu/ml and was pressurized to up to 8 atm above ambient pressure for 10 min. Histochemical analysis demonstrated a positive transgene expression in all layers of the vessel wall. Gene transfer with 8 atm pressurization resulted in an approximately 50 times higher transgene expression than that without pressurization. Under 8 atm pressurization, the efficiency of gene transfer reached a plateau at 7.5 min. The application of hydrostatic pressure may improve the effectiveness of intraoperative genetic engineering of vein grafts

Design of fiber coupled Er3+: Chalcogenide microsphere amplifier via particle swarm optimization algorithm

International audienceA mid-IR amplifier consisting of a tapered chalcogenide fiber coupled to an Er3+-doped chalcogenide microsphere has been optimized via a particle swarm optimization (PSO) approach. More precisely, a dedicated three-dimensional numerical model, based on the coupled mode theory and solving the rate equations, has been integrated with the PSO procedure. The rate equations have included the main transitions among the erbium energy levels, the amplified spontaneous emission, and the most important secondary transitions pertaining to the ion-ion interactions. The PSO has allowed the optimal choice of the microsphere and fiber radius, taper angle, and fiber-microsphere gap in order to maximize the amplifier gain. The taper angle and the fiber-microsphere gap have been optimized to efficiently inject into the microsphere both the pump and the signal beams and to improve their spatial overlapping with the rare-earth-doped region. The employment of the PSO approach shows different attractive features, especially when many parameters have to be optimized. The numerical results demonstrate the effectiveness of the proposed approach for the design of amplifying systems. The PSO-based optimization approach has allowed the design of a microsphere-based amplifying system more efficient than a similar device designed by using a deterministic optimization method. In fact, the amplifier designed via the PSO exhibits a simulated gain G=33.7 dB, which is higher than the gain G=6.9 dB of the amplifier designed via the deterministic method