Current relaxation in nonlinear random media

We study the current relaxation of a wave packet in a nonlinear random sample coupled to the continuum and show that the survival probability decays as $P(t) \sim 1/t^{\alpha}$. For intermediate times $t<t^*$, the exponent $\alpha$ satisfies a scaling law $\alpha =f(\Lambda=\chi/l_{\infty})$ where $\chi$ is the nonlinearity strength and $l_{\infty}$ is the localization length of the corresponding random system with $\chi=0$. For $t\gg t^*$ and $\chi>\chi_{\rm cr}$ we find a universal decay with $\alpha=2/3$ which is a signature of the {\it nonlinearity-induced delocalization}. Experimental evidence should be observable in coupled nonlinear optical waveguides.Comment: revised version, PRL in press, 4 pages, 4 figs (fig 3 with reduced quality

The signature of subsurface Kondo impurities in the local tunnel current

The conductance of a tunnel point-contact in an STM-like geometry having a single defect placed below the surface is investigated theoretically. The effect of multiple electron scattering by the defect after reflections by the metal surface is taken into account. In the approximation of s-wave scattering the dependence of the conductance on the applied voltage and the position of the defect is obtained. The results are illustrated for a model s-wave phase shift describing Kondo-resonance scattering. We demonstrate that multiple electron scattering by the magnetic impurity plays a decisive role in the point-contact conductance at voltages near the Kondo resonance. We find that the sign and shape of the Kondo anomaly depends on the position of the defect.Comment: 13 pages, 4 figures. To be published in J. Phys.: Cond. Ma

Reversing conditional orderings

We analyze some specific aspects concerning conditional orderings and relations among them. To this purpose we define a suitable concept of reversed conditional ordering and prove some related results. In particular we aim to compare the univariate stochastic orderings ≤ st, ≤ hr, and ≤ lr in terms of differences among different notions of conditional orderings. Some applications of our result to the analysis of positive dependence will be detailed. We concentrate attention to the case of a pair of scalar random variables X, Y ​. Suitable extensions to multivariate cases are possible

Generalized Ladder Operators for Shape-invariant Potentials

A general form for ladder operators is used to construct a method to solve bound-state Schr\"odinger equations. The characteristics of supersymmetry and shape invariance of the system are the start point of the approach. To show the elegance and the utility of the method we use it to obtain energy spectra and eigenfunctions for the one-dimensional harmonic oscillator and Morse potentials and for the radial harmonic oscillator and Coulomb potentials.Comment: in Revte

TRAIL Coated Genetically Engineered Immunotherapeutic Nano-Ghosts Vesicles Target Human Melanoma-Avoiding the Need for High Effective Therapeutic Concentration of TRAIL

Cancer cell therapy using cytotoxic T lymphocytes (CTL) or mesenchymal stem cells (MSC) possesses hurdles due to the cells, susceptibility to host induced changes. Here, versatile inanimate broadly applicable nanovesicles, termed immunotherapeutic-nano-ghosts (iNGs), are armed with inherent surface-associated targeting and therapeutic capabilities in which the promise and benefits of MSC therapy and T cell immunotherapy are combined into one powerful off-the-shelf approach for treating malignant diseases. To mimic the cytotoxic or immunosuppressive functions of T cells, iNG are produced from MSC that were genetically engineered (GE) or metabolically manipulated to express additional membrane-bound proteins, endowing the NGs derived therefrom with additional surface-associated functions such as tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL). iNGs from GE-MSCs (GE-iNGs) show superior TRAIL retention and induce apoptosis in different cancer cell lines in vitro. In vivo studies on a human melanoma model demonstrate that a systemic, three-day frequency, administration of GE-iNGs result in tumor inhibition comparable to a six orders of magnitude higher concentration of soluble TRAIL. The iNGs are therefore a promising nanovesicle platform that can affect tumors in a non-immunogenic manner while avoiding the need for a highly effective therapeutic concentration

Parametrization of the octupole degrees of freedom

A simple parametrization for the octupole collective variables is proposed and the symmetries of the wave functions are discussed in terms of the solutions corresponding to the vibrational limit. [PACS: 21.60Ev, 21.60.Fw, 21.10.Re]Comment: 14 page

Soliton tunneling with sub-barrier kinetic energies

We investigate (theoretically and numerically) the dynamics of a soliton moving in an asymmetrical potential well with a finite barrier. For large values of the width of the well, the width of the barrier and/or the height of the barrier, the soliton behaves classically. On the other hand, we obtain the conditions for the existence of soliton tunneling with sub-barrier kinetic energies. We apply these results to the study of soliton propagation in disordered systems.Comment: 6 eps figures. To appear in Physical Review E (Rapid Communications

Conformally parametrized surfaces associated with CP^(N-1) sigma models

Two-dimensional conformally parametrized surfaces immersed in the su(N) algebra are investigated. The focus is on surfaces parametrized by solutions of the equations for the CP^(N-1) sigma model. The Lie-point symmetries of the CP^(N-1) model are computed for arbitrary N. The Weierstrass formula for immersion is determined and an explicit formula for a moving frame on a surface is constructed. This allows us to determine the structural equations and geometrical properties of surfaces in R^(N^2-1). The fundamental forms, Gaussian and mean curvatures, Willmore functional and topological charge of surfaces are given explicitly in terms of any holomorphic solution of the CP^2 model. The approach is illustrated through several examples, including surfaces immersed in low-dimensional su(N) algebras.Comment: 32 page

Predatory Bacteria: A Potential Ally against Multidrug-Resistant Gram-Negative Pathogens

Multidrug-resistant (MDR) Gram-negative bacteria have emerged as a serious threat to human and animal health. Bdellovibrio spp. and Micavibrio spp. are Gram-negative bacteria that prey on other Gram-negative bacteria. In this study, the ability of Bdellovibrio bacteriovorus and Micavibrio aeruginosavorus to prey on MDR Gram-negative clinical strains was examined. Although the potential use of predatory bacteria to attack MDR pathogens has been suggested, the data supporting these claims is lacking. By conducting predation experiments we have established that predatory bacteria have the capacity to attack clinical strains of a variety of ß-lactamase-producing, MDR Gram-negative bacteria. Our observations indicate that predatory bacteria maintained their ability to prey on MDR bacteria regardless of their antimicrobial resistance, hence, might be used as therapeutic agents where other antimicrobial drugs fail. © 2013 Kadouri et al