Strain sensing based on radiative emission-absorption mechanism using dye-doped polymer optical fiber

A stress sensor based on a dye-doped polymeric optical fiber is able to detect stress by simple comparison of two luminescence peaks from a pair of energy transfer organic dyes. Coumarin 540A (donor) and Rhodamine 6G (acceptor) were doped in the core and cladding of the fiber, respectively. For various laser wavelengths, the change in the near-field pattern and visible emission spectrum upon variation in the fiber bending diameter was evaluated. From a comparison with a low-numerical-aperture fiber, it is shown that the sensitivity of the sensor is controllable by optimization of the waveguide parameters

On the possibility of generating a 4-neutron resonance with a {\boldmath T=3/2T=3/2} isospin 3-neutron force

We consider the theoretical possibility to generate a narrow resonance in the four neutron system as suggested by a recent experimental result. To that end, a phenomenological $T=3/2$ three neutron force is introduced, in addition to a realistic $NN$ interaction. We inquire what should be the strength of the $3n$ force in order to generate such a resonance. The reliability of the three-neutron force in the $T=3/2$ channel is exmined, by analyzing its consistency with the low-lying $T=1$ states of $^4$H, $^4$He and $^4$Li and the $^3{\rm H} + n$ scattering. The {\it ab initio} solution of the $4n$ Schr\"{o}dinger equation is obtained using the complex scaling method with boundary conditions appropiate to the four-body resonances. We find that in order to generate narrow $4n$ resonant states a remarkably attractive $3N$ force in the $T=3/2$ channel is required.Comment: 11 pages, 11 figures, minor change, published version, to be published in Physical Review

Deformations of Maxwell Superalgebras and Their Applications

We describe the Lie algebra deformations of D=4 Maxwell superalgebra that was recently introduced as the symmetry algebra of a kappa-symmetric massless superparticle in a supersymmetric constant electromagnetic background. Further we introduce the D=3 Maxwell superalgebra and present all its possible deformations. Finally the deformed superalgebras are used to derive via a contraction procedure the complete set of Casimir operators for D=4 and D=3 Maxwell superalgebras.Comment: 30 pages, 1 figure, Comments and a reference adde

Deformed Maxwell Algebras and their Realizations

We study all possible deformations of the Maxwell algebra. In D=d+1\neq 3 dimensions there is only one-parameter deformation. The deformed algebra is isomorphic to so(d+1,1)\oplus so(d,1) or to so(d,2)\oplus so(d,1) depending on the signs of the deformation parameter. We construct in the dS (AdS) space a model of massive particle interacting with Abelian vector field via non-local Lorentz force. In D=2+1 the deformations depend on two parameters b and k. We construct a phase diagram, with two parts of the (b,k) plane with so(3,1)\oplus so(2,1) and so(2,2)\oplus so(2,1) algebras separated by a critical curve along which the algebra is isomorphic to Iso(2,1)\oplus so(2,1). We introduce in D=2+1 the Volkov-Akulov type model for a Abelian Goldstone-Nambu vector field described by a non-linear action containing as its bilinear term the free Chern-Simons Lagrangean.Comment: 10 pages, Talk based on [1] in the XXV-th Max Born Symposium "Planck Scale", held in Wroclaw 29.06-3.07.200

Relay Backpropagation for Effective Learning of Deep Convolutional Neural Networks

Learning deeper convolutional neural networks becomes a tendency in recent years. However, many empirical evidences suggest that performance improvement cannot be gained by simply stacking more layers. In this paper, we consider the issue from an information theoretical perspective, and propose a novel method Relay Backpropagation, that encourages the propagation of effective information through the network in training stage. By virtue of the method, we achieved the first place in ILSVRC 2015 Scene Classification Challenge. Extensive experiments on two challenging large scale datasets demonstrate the effectiveness of our method is not restricted to a specific dataset or network architecture. Our models will be available to the research community later.Comment: Technical report for our submissions to the ILSVRC 2015 Scene Classification Challenge, where we won the first plac

Super-Weyl Invariant 2D Supergravity, Anomaly and WZ Action

We present a candidate of anomaly and Wess Zumino action of the two dimensional supergravity coupling with matters in a super-Weyl invariant regularization. It is a generalization of the Weyl and the area preserving \Diff invariant formulation of two dimensional gravity theory.Comment: 9 pages, Late

Electronic Structure of Copper Impurities in ZnO

We have measured the near infrared absorption, Zeeman effect, and electron spin resonance of Cu2+ ions introduced as a substitutional impurity into single-crystal ZnO. From the g values of the lowest Γ6 component of the T2 state (the ground state), gII=0.74 and g⊥=1.531, and from the g values of the Γ4Γ5 component of the E state, gII=1.63 and g⊥=0, we have determined the wave functions of Cu2+ in terms of an LCAO MO model in which overlap only with the first nearest neighbor oxygen ions is considered. These wave functions indicate that the copper 3d (t2) hole spends about 40% of its time in the oxygen orbitals, and that the copper t2 orbitals are expanded radially with respect to the e orbitals. Corroboration for the radial expansion of the t2 orbitals is obtained from an analysis of the hyperfine splitting. It is concluded from our model that the large values of the hyperfine constants, |A|=195×10^-4 cm^-1 and |B|=231×10^-4 cm^-1, are due to the contribution from the orbital motion of the t2 hole

Evidence of ratchet effect in nanowires of a conducting polymer

Ratchet effect, observed in many systems starting from living organism to artificially designed device, is a manifestation of motion in asymmetric potential. Here we report results of a conductivity study of Polypyrrole nanowires, which have been prepared by a simple method to generate a variation of doping concentration along the length. This variation gives rise to an asymmetric potential profile that hinders the symmetry of the hopping process of charges and hence the value of measured resistance of these nanowires become sensitive to the direction of current flow. The asymmetry in resistance was found to increase with decreasing nanowire diameter and increasing temperature. The observed phenomena could be explained with the assumption that the spatial extension of localized state involved in hopping process reduces as the doping concentration reduces along the length of the nanowires.Comment: Revtex, two column, 4 pages, 10 figure