192 research outputs found
Quantum non-stationary phenomena of spin systems in collision models
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
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
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
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
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
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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