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

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

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

Detection of high-risk human papillomavirus RNA in urine for cervical cancer screening with HPV 16 & 18/45 genotyping

© 2020 The Authors Objective: To detect high-risk human papillomavirus (hrHPV) messenger-RNA (mRNA) in urine samples, compare their concordance with cervical samples including HPV 16 & 18/45 genotyping, and to determine the utility in detecting ≥ CIN 2 lesions. Methods: A cohort of 189 non-pregnant patients (age ≥ 25) was recruited in three groups: Group 1 with abnormal pap-smears and hrHPV positivity, Group 2 with normal pap-smears and hrHPV positivity, and Group 3 with normal pap-smears and hrHPV negativity. Urine samples were tested for hrHPV-mRNA and subsequent hrHPV-mRNA genotype if positive. High-risk HPV detection and genotyping were performed using Aptima assays which are validated for cervical HPV testing. Colposcopy results from groups 1 & 2 were analyzed. Results: The sensitivity of urine hrHPV-mRNA detection was 31.5% while the specificity and PPV were above 95% (96.9% & 95.1% respectively) (p \u3c 0.001). The kappa agreement with cervical samples was fair (0.22, p = 0.04). The sensitivity and specificity of urine hrHPV-mRNA genotyping were 20.0% & 100% respectively (p \u3c 0.001) with 100% genotype-specific concordance. The kappa agreement with cervical samples was fair (0.25, p = 0.16). For urine hrHPV-mRNA detection of ASC-H/HSIL when grouped by age ≥ 30, the sensitivity and specificity were 45.4% & 63.9% respectively (p = 0.009). For urine hrHPV-mRNA detection of ≥ CIN 2 for all ages, the sensitivity and specificity were 45.5% & 75.0% respectively (p = 0.03). Conclusion: Using the Aptima Assay, urine hrHPV-mRNA detection is suboptimal for cervical cancer screening but given the high specificity, it has the potential to identify high-grade lesions (≥ CIN 2). Urine hrHPV-mRNA genotyping via this modality is not beneficial in triage settings of normal or abnormal cytology to determine the need for colposcopy

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

Comparative analysis of the structure and internal stress in Ti-6Al-4V alloys manufactured by 3D printing and processing with screw extrusion

Study is based on the compare characterization of the structure and evaluation of the residual internal stresses in Ti-6Al-4V samples manufactured by the 3D printing (selective laser melting) and in the Ti-6Al-4V samples obtained with using of the severe plastic deformation by screw extrusion. The microstructure and residual stresses were examined by transmission electron microscope and X-ray diffractometer. High tensile internal residual stresses in the 3D printed sample were found. The high compressive residual internal stresses were found in the hot pressed and in the twisted samples. It was shown that arising of the high residual stresses in the studied samples under various technological processes occurred in various ways. The residual stresses in the severe plastic deformed samples arose due to non-uniform volumetric plastic deformation. In 3D printed sample, the residual tensile stresses arose from both phase (martensitic) transformation and thermal deformation. © Published under licence by IOP Publishing Ltd

Magnetic properties of polymerized C60_{60} with Fe

We provide evidence that high-pressure high-temperature (2.5 GPa and 1040 K) treatment of mixtures of iron with fullerene powders leads to the complete transformation of iron into iron carbide Fe$_3$C. The comparison of the magnetic properties (Curie temperature and magnetic moment) of the here studied samples and those for the ferromagnetic polymer Rh-C$_{60}$ indicates that the main ferromagnetic signal reported in those samples is due to Fe$_3$C and not related to the ferromagnetism of carbon as originally interpreted. Taking into account the results obtained in this study the original paper on ``Magnetic carbon" (Nature {\bf 413}, 716 (2001)) was recently retracted.Comment: 5 Figures, 4 page