Scaling laws for non-Hermitian skin effect with long-range couplings

Recent years have witnessed a surge of research on the non-Hermitian skin effect (NHSE) in one-dimensional lattices with finite-range couplings. In this work, we show that the long-range couplings that decay as $1/l^{\alpha}$ at distance $l$ can fundamentally modify the behavior of NHSE and the scaling of quantum entanglement in the presence of nonreciprocity. At $\alpha=0$, the nonlocality of couplings gives rise to the scale-free skin modes, whose localization length is proportional to the system size. Increasing the exponent $\alpha$ drives a complex-to-real spectral transition and a crossover from a scale-free to constant localization length. Furthermore, the scaling of nonequilibrium steady-state entanglement entropy exhibits a subextensive law due to the nonlocality and the complex spectrum, in contrast to an area law arising from NHSE. Our results provide a theoretical understanding on the interplay between long-range couplings and non-Hermiticity.Comment: 6 pages, 4 figure

Non-Hermitian skin effects on many-body localized and thermal phases

Localization in one-dimensional interacting systems can be caused by disorder potentials or non-Hermiticity. The former phenomenon is the many-body localization (MBL), and the latter is the many-body non-Hermitian skin effect (NHSE). In this work, we numerically investigate the interplay between these two kinds of localization, where the energy-resolved MBL arises from a deterministic quasiperiodic potential in a fermionic chain. We propose a set of eigenstate properties and long-time dynamics that can collectively distinguish the two localization mechanisms in the presence of non-Hermiticity. By computing the proposed diagnostics, we show that the thermal states are vulnerable to the many-body NHSE while the MBL states remain resilient up to a strong non-Hermiticity. Finally, we discuss experimental observables that can probe the difference between the two localizations in a non-Hermitian quasiperiodic fermionic chain. Our results pave the way toward experimental observations on the interplay of interaction, quasiperiodic potential, and non-Hermiticity.Comment: 7 pages, 4 figure

Quasi-Hermitian extended SSH models

We consider the quasi Hermitian limit of a non-Hermitian extended Su Schrieffer Heeger model, in which the hopping amplitudes obey a specific relation so that the system may be mapped to a corresponding Hermitian one and its energy spectrum is completely real. Analogous to the Hermitian case, one may use the modified winding number to determine the total number of edge states on the boundaries to achieve a modified bulk-boundary correspondence. Due to the skin effect in nonHermitian systems, the spectral winding numbers must be used to classify such systems further. It dictates how the edge states would be distributed over the left and right boundaries. We then naively extend the criteria to the cases that the quasi Hermitian condition is violated. For all the cases that we consider, no inconsistency has been found.Comment: 21 pages, 10 figure

Oil and Vinegar: Modern Parameters and Implementations

Two multivariate digital signature schemes, Rainbow and GeMSS, made it into the third round of the NIST PQC competition. However, either made its way to being a standard due to devastating attacks (in one case by Beullens, the other by Tao, Petzoldt, and Ding). How should multivariate cryptography recover from this blow? We propose that, rather than trying to fix Rainbow and HFEv- by introducing countermeasures, the better approach is to return to the classical Oil and Vinegar scheme. We show that, if parametrized appropriately, Oil and Vinegar still provides competitive performance compared to the new NIST standards by most measures (except for key size). At NIST security level 1, this results in either 128-byte signatures with 44 kB public keys or 96-byte signatures with 67 kB public keys. We revamp the state-of-the-art of Oil and Vinegar implementations for the Intel/AMD AVX2, the Arm Cortex-M4 microprocessor, the Xilinx Artix-7 FPGA, and the Armv8-A microarchitecture with the Neon vector instructions set

NTT Multiplication for NTT-unfriendly Rings

In this paper, we show how multiplication for polynomial rings used in the NIST PQC finalists Saber and NTRU can be efficiently implemented using the Number-theoretic transform (NTT). We obtain superior performance compared to the previous state of the art implementations using Toom–Cook multiplication on both NIST’s primary software optimization targets AVX2 and Cortex-M4. Interestingly, these two platforms require different approaches: On the Cortex-M4, we use 32-bit NTT-based polynomial multiplication, while on Intel we use two 16-bit NTT-based polynomial multiplications and combine the products using the Chinese Remainder Theorem (CRT). For Saber, the performance gain is particularly pronounced. On Cortex-M4, the Saber NTT-based matrix-vector multiplication is 61% faster than the Toom-Cook multiplication resulting in 22% fewer cycles for Saber encapsulation. For NTRU, the speed-up is less impressive, but still NTT-based multiplication performs better than Toom–Cook for all parameter sets on Cortex-M4. The NTT-based polynomial multiplication for NTRU-HRSS is 10% faster than Toom–Cook which results in a 6% cost reduction for encapsulation. On AVX2, we obtain speed-ups for three out of four NTRU parameter sets. As a further illustration, we also include code for AVX2 and Cortex-M4 for the Chinese Association for Cryptologic Research competition award winner LAC (also a NIST round 2 candidate) which outperforms existing code

Acetylome of acinetobacter baumannii SK17 reveals a highly-conserved modification of histone-like protein HU

Lysine acetylation is a prevalent post-translational modification in both eukaryotes and prokaryotes. Whereas this modification is known to play pivotal roles in eukaryotes, the function and extent of this modification in prokaryotic cells remain largely unexplored. Here we report the acetylome of a pair of antibiotic-sensitive and -resistant nosocomial pathogen Acinetobacter baumannii SK17-S and SK17-R. A total of 145 lysine acetylation sites on 125 proteins was identified, and there are 23 acetylated proteins found in both strains, including histone-like protein HU which was found to be acetylated at Lys13. HU is a dimeric DNA-binding protein critical for maintaining chromosomal architecture and other DNA-dependent functions. To analyze the effects of site-specific acetylation, homogenously Lys13-acetylated HU protein, HU(K13ac) was prepared by genetic code expansion. Whilst not exerting an obvious effect on the oligomeric state, Lys13 acetylation alters both the thermal stability and DNA binding kinetics of HU. Accordingly, this modification likely destabilizes the chromosome structure and regulates bacterial gene transcription. This work indicates that acetyllysine plays an important role in bacterial epigenetics

Heavy Metal Removal from Wastewater Using Zero-Valent Iron Nanoparticles

[[abstract]]本研究之目的為針對奈米零價鐵技術處理重金屬 (Cu、Zn、Pb、Ni、Cr) 溶液之反應進行探討。藉由批次試驗的進行，針對起始 pH值、奈米零價鐵添加量及重金屬溶液初始濃度等影響因子，探討其對奈米零價鐵去除重金屬 (Cu、Zn、Pb、Ni、Cr) 的影響，並進行 XRD 分析，以了解鐵粉反應號表面生成物的形態。。 研究結果發現在不同 pH (2、3、4、5)條件下，奈米零價鐵粉處理重金屬溶液之效率與反應速率皆隨初始 pH值的降低而有明顯的增加。當溶液初始 pH 值為 2 時，銅、鋅、鉛、鉻等重金屬溶液都能達到 90% 以上的去除率，其去除效率是 Cu = Cr > Zn = Pb > Ni。 另外，在不同奈米零價鐵粉添加量 (0 5、2 0、2 75、3 5、5 0 g/L) 之試驗中，可以看出重金屬的反應速率常數與去除效率隨著鐵添加量的增加有明顯的上升趨勢。而當鐵粉添加量增加到 2 0 g/L 時，銅、鋅、鉛、鉻等重金屬溶液都能有超過80 % 以上的去除效果，可看出在此鐵粉添加量下對於重金屬溶液即有不錯的去除效果。 由不同金屬溶液初始濃度 (1、34、50 5、67、100 mg/L) 之實驗結果可以得知，隨著金屬濃度的增加其反應速率常數及去除率都有所下降。一般而言，奈米零價鐵對於重金屬廢水的去除效率能以擬一階反應動力式加以描述。 而由 XRD分析之結果可以看出，反應過後之奈米零價鐵粉主要形成r-FeOOH 及 Fe6(OH)12SO4．nH2O 或 Fe(II)Fe(III)3(OH)12Cl3．H2O 等鐵的腐蝕氧化物。[[abstract]]The purpose of this study was aimed to investigate the reaction behavior of heavy metals (Cu、Zn、Pb、Ni、Cr) with zero-valent iron (ZVI) nanoparticles in the wastewater The influence factors such as initial pH dosage of nanoscale ZVI and initial concentration of heavy metal on the removal efficiency of heavy metals by ZVI in the wastewater were examined by the batch experiments in this study Furthermore the analysis of X-ray diffraction (XRD) was carried out to observe the products on the ZVI surface after the treatment of heavy metals from the wastewater The results showed that the removal of heavy metals was affected by initial pH The rate and efficiency of metal removal increased with decreasing initial pH Higher than 90 % of the heavy metals (Cu、Zn、Pb、Cr) was removed when the initial pH was controlled at 2 The removal efficiency of heavy metal were in the decreasing order: Cu = Cr > Zn = Pb > Ni In addition the rate and efficiency of metal removal increased as the dosage of nanoscale ZVI increased The removal efficiency of heavy metal was higher than 80% when 2 0 g/L of ZVI was added in the wastewater On the other hand the slow rate and low efficiency of metal removal from the wastewater treated by nanoscale ZVI was found in the wastewater with high concentration of heavy metal Generally the removal kinetic of heavy metals from the wastewater by nanoscale ZVI was well described by the pseudo-first order reaction The XRD analysis revealed that iron corrosion products including r-FeOOH、 Fe6(OH)12SO4．nH2O and/or Fe(II)Fe(III)3(OH)12Cl3．H2O were formed at the surface of nanoscale ZVI particles after the treatment of heavy metals from the wastewate

Generalized path–permutation codes for reliable end-to-end networking of opportunistic links

Opportunistic links are emerging as a novel technology for state-of-the-art wireless networks, such as cognitive radio networks, energy-harvesting networks, and low-latency vehicular networks. To increase the reliability of these networks, path-permutation codes (PPCs) were advocated in [1] . These codes are based on a virtual multiple-input multiple-output (MIMO) model on the session/network layer, and have been tailored for increased reliability of opportunistic links. By exploiting multipath–multihop routes, PPCs access one relay path at a time while repeatedly transmitting the same QAM symbol. In this paper, we introduce a generalized PPC scheme which simultaneously accesses multiple relay paths and comprises multiple QAM symbols in the packet. Phase rotations are also introduced in the PPC codewords for additional performance improvement. Numerical simulation results validate our analyses and demonstrate the superior performance of this novel coding scheme, i.e., better error rate performance, higher throughput, and stronger robustness to transmission outages.The work of I-Wei Lai was supported by Ministry of Science and Technology, Taiwan, under Grant MOST 108-2221-E-003-002-MY3. K.-C. Chen’s research is supported in part by the Cyber Florida. The work of Ezio Biglieri was supported by the H2020 Framework Programme/ERC grant 694974

Biomechanical Comparison of a Novel Implant and Commercial Fixation Devices for AO/OTA 43-C1 Type Distal Tibial Fracture

This study compares the novel Asia Distal Lateral Tibial Locking Plate mechanical stability to that of the current anterolateral and medial tibial plates based on finite element analysis. Four-part fracture fragment model of the distal tibia was reconstructed using CAD software. A load was applied to simulate the swing phase of gait. The implant stress and the construct stiffness were compared. The results of the anterolateral plate and the medial plate were similar and the displacement values were determined lower than those in the medial plate. In the simulated distal tibia fracture, the Aplus Asia Distal Lateral Tibial Locking Plate and medial distal tibial plate tibia fixations will lead to a stiffer bone-implant construct compared to the anterolateral distal tibial plate. Moreover, the stress in the Aplus Asia Distal Lateral Tibial Locking Plate was lower than those for the medial distal tibial plate and anterolateral bone plates. The Aplus Asia Distal Lateral Tibial Locking Plate has better stabilization and is an anterolateral plate that avoids more soft tissue damage than other bone plates. The Aplus Asia Distal Lateral Tibial Locking Plate could be one of a suitable design in tibia distal fracture fixation