Security boundaries of an optical power limiter for protecting quantum key distribution systems

Unauthorized light injection has always been a vital threat to the practical security of a quantum key distribution (QKD) system. An optical power limiter (OPL) based on the thermo-optical defocusing effect has been proposed and implemented, limiting the injected hacking light. As a hardware countermeasure, the performance of the OPL under various light-injection attacks shall be tested to clarify the security boundary before being widely deployed. To investigate the OPL's security boundary in quantum cryptography, we comprehensively test and analyse the behavior of OPL under continuous-wave (c.w.) light-injection attacks and pulse illumination attacks with pulses' repetition rate at 0.5-Hz,40-MHz, and 1-GHz. The testing results illuminate the security boundary of the OPL, which allows one to properly employ the OPL in the use cases. The methodology of testing and analysis proposed here is applicable to other power-limitation components in a QKD system.Comment: 14 pages, 13 figure

DFTTK: Density Functional Theory Tool Kit for High-throughput Calculations of Thermodynamic Properties at Finite Temperatures

In this work, we present a software package in Python for high-throughput first-principles calculations of thermodynamic properties at finite temperatures, which we refer to as DFTTK (Density Functional Theory Tool Kit). DFTTK is based on the atomate package and integrates our experiences in the last decades on the development of theoretical methods and computational software. It includes task submissions on all major operating systems and task execution on high-performance computing environments. The distribution of the DFTTK package comes with examples of calculations of phonon density of states, heat capacity, entropy, enthalpy, and free energy under the quasi-harmonic phonon scheme for the stoichiometric phases of Al, Ni, Al3Ni, AlNi, AlNi3, Al3Ni4, and Al3Ni5, and the fcc solution phases treated using the special quasirandom structures at the compositions of Al3Ni, AlNi, and AlNi3.Comment: 49 pages, 18 figure

Circulating miR-122 Is a Predictor for Virological Response in CHB Patients With High Viral Load Treated With Nucleos(t)ide Analogs

Chronic hepatitis B (CHB) infection remains worldwide health problem. Antiviral treatment options for CHB patients include nucleos(t)ide analogs (NAs) and interferon. Most of the current biomarkers for predicting treatment response are virus-dependent. MicroRNA-122 is the most abundant liver-specific miRNA and has been identified involved in multiple liver physiology and pathology including hepatotropic virus infection. To identify the role of miR-122 in NA therapy, 80 CHB patients with high viral load (HVL) were enrolled and serum miR-122 levels at baseline, week 12 and week 24 were measured. Serum miR-122 levels were significantly lower in patients who developed virological response (VR), compared with non-VR group. Levels of miR-122 at week 12 and week 24 were determined to be independent prognostic indicators for a VR with satisfactory AUROC values at 0.812 and 0.800, respectively. During NA therapy, serum miR-122 level deceased steadily and an earlier reduction was observed in VR group, indicating early reduction of miR-122 level might increase the possibility of developing virological response. In conclusion, we identified the dynamic change of serum miR-122 level and miR-122 levels at week 12 and week 24 as independent predictors for VR in CHB patients with HVL treated with NAs

Robust passivity and passification of stochastic fuzzy time-delay systems

The official published version can be obtained from the link below.In this paper, the passivity and passification problems are investigated for a class of uncertain stochastic fuzzy systems with time-varying delays. The fuzzy system is based on the Takagi–Sugeno (T–S) model that is often used to represent the complex nonlinear systems in terms of fuzzy sets and fuzzy reasoning. To reflect more realistic dynamical behaviors of the system, both the parameter uncertainties and the stochastic disturbances are considered, where the parameter uncertainties enter into all the system matrices and the stochastic disturbances are given in the form of a Brownian motion. We first propose the definition of robust passivity in the sense of expectation. Then, by utilizing the Lyapunov functional method, the Itô differential rule and the matrix analysis techniques, we establish several sufficient criteria such that, for all admissible parameter uncertainties and stochastic disturbances, the closed-loop stochastic fuzzy time-delay system is robustly passive in the sense of expectation. The derived criteria, which are either delay-independent or delay-dependent, are expressed in terms of linear matrix inequalities (LMIs) that can be easily checked by using the standard numerical software. Illustrative examples are presented to demonstrate the effectiveness and usefulness of the proposed results.This work was supported by the Teaching and Research Fund for Excellent Young Teachers at Southeast University of China, the Specialized Research Fund for the Doctoral Program of Higher Education for New Teachers 200802861044, the National Natural Science Foundation of China under Grant 60804028 and the Royal Society of the United Kingdom

Dynamic analysis of a flexible rotor supported by ball bearings with damping rings based on FEM and lumped mass theory

A dynamic model of a flexible rotor supported by ball bearings with rubber damping rings was proposed by combining the finite element and the mass-centralized method. In the proposed model, the rotor was built with the Timoshenko beam element, while the supports and bearing outer rings were modelled by the mass-centralized method. Meanwhile, the influences of the rotor’s gravity, unbalanced force and nonlinear bearing force were considered. The governing equations were solved by precise integration and the Runge-Kutta hybrid numerical algorithm. To verify the correctness of the modelling method, theoretical and experimental analysis is carried out by a rotor-bearing test platform, where the error rate between the theoretical and experimental studies is less than 10%. Besides that, the influence of the rubber damping ring on the dynamic properties of the rotor-bearing coupling system is also analyzed. The conclusions obtained are in agreement with the real-world deployment. On this basis, the bifurcation and chaos behaviors of the coupling system were carried out with rotational speed and rubber damping ring’s stiffness. The results reveal that as rotational speed increases, the system enters into chaos by routes of crisis, quasi-periodic and intermittent bifurcation. However, the paths of crisis, quasi-periodic bifurcation, and Hopf bifurcation to chaos were detected under the parameter of rubber damping ring’s stiffness. Additionally, the bearing gap affects the rotor system’s dynamic characteristics. Moreover, the excessive bearing gap will make the system’s periodic motion change into chaos, and the rubber damping ring’s stiffness has a substantial impact on the system motion

Changes of outer retinal thickness with increasing age in normal eyes

AIM:To comprehensively investigate the relationship between outer retinal layer thickness and age in normal eyes.METHODS: One hundred normal eyes of 100 subjects who underwent spectral-domain optical coherence tomography(SD-OCT)were included in this retrospective study. The distances between the external limiting membrane(ELM)line and the photoreceptor inner segment/outer segment(IS/OS)line(ELM-IS/OS), the IS/OS line and the cone outer segment tips(COST)line(IS/OS-COST), the COST line and the retinal pigment epithelium(RPE)complex(COST-RPE)and the full retinal thickness(RT)were measured at the fovea and on four quarters. The relationship between thickness and age or sex was then analysed.RESULTS: A thinner RT was observed in women in a multiple regression analysis(men: 234.47±16.79 μm; women: 223.13±15.43 μm). The RT on the nasal quarter and the ELM-IS/OS thickness at the fovea and on the four quarters were significantly and negatively correlated with age. The IS/OS-COST and COST-RPE thicknesses at the fovea and on the four quarters were not significantly correlated with age or sex, respectively. The RT at the fovea was significantly thinner than on the four quarters. The ELM-IS/OS, IS/OS-COST and COST-RPE thicknesses at the fovea were significantly thicker than on the four quarters. CONCLUSION: In normal eyes, the RT thickness on the nasal quarter and the ELM-IS/OS thickness were significantly and negatively correlated with age. The IS/OS-COST and COST-RPE thicknesses were not significantly correlated with age or sex

Conceptual design and progress of transmitting ∼\sim MV DC HV into 4 K LHe detectors

A dual-phase TPC (Time Projection Chamber) is more advanced in characterizing an event than a single-phase one because it can, in principle, reconstruct the 3D (X-Y-Z) image of the event, while a single-phase detector can only show a 2D (X-Y) picture. As a result, more enriched physics is expected for a dual-phase detector than a single-phase one. However, to build such a detector, DC HV (High Voltage) must be delivered into the chamber (to have a static electric field), which is a challenging task, especially for an LHe detector due to the extremely low temperature, $\sim$ 4 K, and the very high voltage, $\sim$ MV (Million Volts). This article introduces a convincing design for transmitting $\sim$ MV DC into a 4 K LHe detector. We also report the progress of manufacturing a 100 kV DC feedthrough capable of working at 4 K. Surprisingly, we realized that the technology we developed here might be a valuable reference to the scientists and engineers aiming to build residential bases on the Moon or Mars

Searching for ER and/or NR-like dark matter signals with the especially low background liquid helium TPCs

In the Dark Matter (DM) direct detection community, the absence of convincing signals has become a ``new normal'' for decades. Among other possibilities, the ``new normal'' might indicate that DM-matter interactions could generate not only the hypothetical NR (Nuclear Recoil) events but also the ER (Electron Recoil) ones, which have often been tagged as backgrounds historically. Further, we argue that ER and NR-like DM signals could co-exist in a DM detector's same dataset. So in total, there would be three scenarios we can search for DM signals: (i) ER excess only, (ii) NR excess only, and (iii) ER and NR excesses combined. To effectively identify any possible DM signal under the three scenarios, a DM detector should (a) have the minimum ER and NR backgrounds and (b) be capable of discriminating ER events from NR ones. Accordingly, we introduce the newly established project, ALETHEIA, which implements liquid helium-filled TPCs (Time Projection Chamber) in hunting for DM. Thanks to the nearly single-digit number of ER and NR backgrounds on 1 ton*yr exposure, presumably, the ALETHEIA detectors should be able to identify any form of DM-induced excess in its ROI (Research Of Interest). As far as we know, ALETHEIA is the first DM direct detection experiment claiming such an inclusive search; conventional detectors search DM mainly on the ``ER excess only'' and/or the ``NR excess only'' channel, not the ``ER and NR excesses combined'' channel. In addition, we introduce a preliminary scheme to one of the most challenging R\&D tasks, transmitting 500+ kV into a 4 K LHe detector