192 research outputs found

    Quantum non-stationary phenomena of spin systems in collision models

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    We investigate the non-stationary phenomenon in a tripartite spin-1/2 system in the collision model (CM) framework. After introducing the dissipation through the system-environment collision for both Markovian and non-Markovian cases, we find the emergence of long-time oscillation in the dynamics of the system and the synchronization among subsystems. We connect the CM description and the quantum master equation in the continuous time limit and explain the existence of the stable oscillation by means of Liouvillian spectrum analysis. The time-dependence of the thermal property and the correlations are investigated, in particular we discuss the possibility of violation of the Landauer's principle in non-Markovian dynamics. In addition, we find that the imperfection of collective dissipation can be compensated by the randomness of the interaction sequence in our CM.Comment: 13 pages, 8 figures, accepted versio

    Dissipation induced quantum synchronization in few-body spin systems

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    We explore the synchronization phenomenon in quantum few-body spin system with the non-local dissipation by quantum trajectory approach. We find that even without external drive, the system can achieve spontaneous synchronization due to the interaction of non-local dissipation, and the time-dependent non-stationarity oscillations can be confirmed through the purely imaginary eigenvalues of the Liouvillian. We theoretically analyze the dissipative dynamics of the system and consider the measure to quantify synchronization through the stochastic quantum trajectories. In each quantum trajectory, it is also possible for the system to ignore dissipative process and build up oscillations in the long-time evolution. We finally investigate the robustness of the oscillations to perturbations, and determine the so-call the largest Lyapunov exponent to confirm the stability of oscillations.Comment: 8 pages, 5 figure

    Power Optimization in Multi-IRS Aided Delay-Constrained IoVT Systems

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    With the advancement of video sensors in the Internet of Things, Internet of Video Things (IoVT) systems, capable of delivering abundant and diverse information, have been increasingly deployed for various applications. However, the extensive transmission of video data in IoVT poses challenges in terms of delay and power consumption. Intelligent reconfigurable surface (IRS), as an emerging technology, can enhance communication quality and consequently improve system performance by reconfiguring wireless propagation environments. Inspired by this, we propose a multi-IRS aided IoVT system that leverages IRS to enhance communication quality, thereby reducing power consumption while satisfying delay requirements. To fully leverage the benefits of IRS, we jointly optimize power control for IoVT devices and passive beamforming for IRS to minimize long-term total power consumption under delay constraints. To solve this problem, we first utilize Lyapunov optimization to decouple the long-term optimization problem into each time slot. Subsequently, an alternating optimization algorithm employing optimal solution-seeking and fractional programming is proposed to effectively solve the optimization problems at each time slot. Simulation results demonstrate that the proposed algorithm significantly outperforms benchmark algorithms in terms of long-term total power consumption. Moreover, a trade-off between the number of IRS elements and system performance is also proved

    Soil Organic Carbon Content and Microbial Functional Diversity Were Lower in Monospecific Chinese Hickory Stands than in Natural Chinese Hickory–Broad-Leaved Mixed Forests

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    To assess the effects of long-term intensive management on soil carbon cycle and microbial functional diversity, we sampled soil in Chinese hickory (Carya cathayensis Sarg.) stands managed intensively for 5, 10, 15, and 20 years, and in reference Chinese hickory–broad-leaved mixed forest (NMF) stands. We analyzed soil total organic carbon (TOC), microbial biomass carbon (MBC), and water-soluble organic carbon (WSOC) contents, applied 13C-nuclear magnetic resonance analysis for structural analysis, and determined microbial carbon source usage. TOC, MBC, and WSOC contents and the MBC to TOC ratios were lower in the intensively managed stands than in the NMF stands. The organic carbon pool in the stands managed intensively for twenty years was more stable, indicating that the easily degraded compounds had been decomposed. Diversity and evenness in carbon source usage by the microbial communities were lower in the stands managed intensively for 15 and 20 years. Based on carbon source usage, the longer the management time, the less similar the samples from the monospecific Chinese hickory stands were with the NMF samples, indicating that the microbial community compositions became more different with increased management time. The results call for changes in the management of the hickory stands to increase the soil carbon content and restore microbial diversity

    Soil Organic Carbon Content and Microbial Functional Diversity Were Lower in Monospecific Chinese Hickory Stands than in Natural Chinese Hickory–Broad-Leaved Mixed Forests

    Get PDF
    To assess the effects of long-term intensive management on soil carbon cycle and microbial functional diversity, we sampled soil in Chinese hickory (Carya cathayensis Sarg.) stands managed intensively for 5, 10, 15, and 20 years, and in reference Chinese hickory–broad-leaved mixed forest (NMF) stands. We analyzed soil total organic carbon (TOC), microbial biomass carbon (MBC), and water-soluble organic carbon (WSOC) contents, applied 13C-nuclear magnetic resonance analysis for structural analysis, and determined microbial carbon source usage. TOC, MBC, and WSOC contents and the MBC to TOC ratios were lower in the intensively managed stands than in the NMF stands. The organic carbon pool in the stands managed intensively for twenty years was more stable, indicating that the easily degraded compounds had been decomposed. Diversity and evenness in carbon source usage by the microbial communities were lower in the stands managed intensively for 15 and 20 years. Based on carbon source usage, the longer the management time, the less similar the samples from the monospecific Chinese hickory stands were with the NMF samples, indicating that the microbial community compositions became more different with increased management time. The results call for changes in the management of the hickory stands to increase the soil carbon content and restore microbial diversity

    Discovery of novel dsRNA viral sequences by in silico cloning and implications for viral diversity, host range and evolution

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    Genome sequence of viruses can contribute greatly to the study of viral evolution, diversity and the interaction between viruses and hosts. Traditional molecular cloning methods for obtaining RNA viral genomes are time-consuming and often difficult because many viruses occur in extremely low titers. DsRNA viruses in the families, Partitiviridae, Totiviridae, Endornaviridae, Chrysoviridae, and other related unclassified dsRNA viruses are generally associated with symptomless or persistent infections of their hosts. These characteristics indicate that samples or materials derived from eukaryotic organisms used to construct cDNA libraries and EST sequencing might carry these viruses, which were not easily detected by the researchers. Therefore, the EST databases may include numerous unknown viral sequences. In this study, we performed in silico cloning, a procedure for obtaining full or partial cDNA sequence of a gene by bioinformatics analysis, using known dsRNA viral sequences as queries to search against NCBI Expressed Sequence Tag (EST) database. From this analysis, we obtained 119 novel virus-like sequences related to members of the families, Endornaviridae, Chrysoviridae, Partitiviridae, and Totiviridae. Many of them were identified in cDNA libraries of eukaryotic lineages, which were not known to be hosts for these viruses. Furthermore, comprehensive phylogenetic analysis of these newly discovered virus-like sequences with known dsRNA viruses revealed that these dsRNA viruses may have co-evolved with respective host supergroups over a long evolutionary time while potential horizontal transmissions of viruses between different host supergroups also is possible. We also found that some of the plant partitiviruses may have originated from fungal viruses by horizontal transmissions. These findings extend our knowledge of the diversity and possible host range of dsRNA viruses and offer insight into the origin and evolution of relevant viruses with their hosts
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