15 research outputs found
Voter model on a directed network: Role of bidirectional opinion exchanges
The voter model with the node update rule is numerically investigated on a
directed network. We start from a directed hierarchical tree, and split and
rewire each incoming arc at the probability . In order to discriminate the
better and worse opinions, we break the symmetry () by
giving a little more preference to the opinion . It is found that
as becomes larger, introducing more complicated pattern of information flow
channels, and as the network size becomes larger, the system eventually
evolves to the state in which more voters agree on the better opinion, even
though the voter at the top of the hierarchy keeps the worse opinion. We also
find that the pure hierarchical tree makes opinion agreement very fast, while
the final absorbing state can easily be influenced by voters at the higher
ranks. On the other hand, although the ordering occurs much slower, the
existence of complicated pattern of bidirectional information flow allows the
system to agree on the better opinion.Comment: 5 pages, 3 figures, Phys. Rev. E (in press
Double resonance in the infinite-range quantum Ising model
We study quantum resonance behavior of the infinite-range kinetic Ising model
at zero temperature. Numerical integration of the time-dependent Schr\"odinger
equation in the presence of an external magnetic field in the direction is
performed at various transverse field strengths . It is revealed that two
resonance peaks occur when the energy gap matches the external driving
frequency at two distinct values of , one below and the other above the
quantum phase transition. From the similar observations already made in
classical systems with phase transitions, we propose that the double resonance
peaks should be a generic feature of continuous transitions, for both quantum
and classical many-body systems.Comment: 4 pages, 5 figure
Synchronization in interdependent networks
We explore the synchronization behavior in interdependent systems, where the
one-dimensional (1D) network (the intranetwork coupling strength )
is ferromagnetically intercoupled (the strength ) to the Watts-Strogatz (WS)
small-world network (the intranetwork coupling strength ). In the
absence of the internetwork coupling (), the former network is well
known not to exhibit the synchronized phase at any finite coupling strength,
whereas the latter displays the mean-field transition. Through an analytic
approach based on the mean-field approximation, it is found that for the weakly
coupled 1D network () the increase of suppresses
synchrony, because the nonsynchronized 1D network becomes a heavier burden for
the synchronization process of the WS network. As the coupling in the 1D
network becomes stronger, it is revealed by the renormalization group (RG)
argument that the synchronization is enhanced as is increased,
implying that the more enhanced partial synchronization in the 1D network makes
the burden lighter. Extensive numerical simulations confirm these expected
behaviors, while exhibiting a reentrant behavior in the intermediate range of
. The nonmonotonic change of the critical value of is
also compared with the result from the numerical RG calculation.Comment: 16 pages, 7 figure
Instability of defensive alliances in the predator-prey model on complex networks
A model of six-species food web is studied in the viewpoint of spatial
interaction structures. Each species has two predators and two preys, and it
was previously known that the defensive alliances of three cyclically predating
species self-organize in two-dimensions. The alliance-breaking transition
occurs as either the mutation rate is increased or interaction topology is
randomized in the scheme of the Watts-Strogatz model. In the former case of
temporal disorder, via the finite-size scaling analysis the transition is
clearly shown to belong to the two-dimensional Ising universality class. In
contrast, the geometric or spatial randomness for the latter case yields a
discontinuous phase transition. The mean-field limit of the model is
analytically solved and then compared with numerical results. The dynamic
universality and the temporally periodic behaviors are also discussed.Comment: 5 page
Structure-activity relationships of fluorene compounds inhibiting HCV variants
Approximately 71 million people suffer from hepatitis C virus (HCV) infection worldwide. Persistent HCV infection causes liver diseases such as chronic hepatitis, liver cirrhosis, and hepatocellular carcinoma, resulting in approximately 400,000 deaths annually. Effective direct-acting antiviral agents (DAAs) have been developed and are currently used for HCV treatment targeting the following three proteins: NS3/4A proteinase that cleaves the HCV polyprotein into various functional proteins, RNA-dependent RNA polymerase (designated as NS5B), and NS5A, which is required for the formation of double membrane vesicles serving as RNA replication organelles. At least one compound inhibiting NS5A is included in current HCV treatment regimens due to the high efficacy and low toxicity of drugs targeting NS5A. Here we report fluorene compounds showing strong inhibitory effects on GT 1b and 3a of HCV. Moreover, some compounds were effective against resistance-associated variants to DAAs. The structure-activity relationships of the compounds were analyzed. Furthermore, we investigated the molecular bases of the inhibitory activities of some compounds by the molecular docking method.11Ysciescopu
Quantum Monte Carlo study of the transverse-field quantum Ising modelon infinite-dimensional structures
In a number of classical statistical-physical models, there exists acharacteristic dimensionality called the upper critical dimension abovewhich one observes the mean-field critical behavior. Instead of constructinghigh-dimensional lattices, however, one can also considerinfinite-dimensional structures, and the question is whether this mean-fieldcharacter extends to quantum-mechanical cases as well. We thereforeinvestigate the transverse-field quantum Ising model on the globally couplednetwork and on the Watts-Strogatz small-world network by means of quantum MonteCarlo simulations and the finite-size scaling analysis. We confirm that bothof the structures exhibit critical behavior consistent with the mean-fielddescription. In particular, we show that the existing cumulant methodhas difficulty in estimating the correct dynamic critical exponent andsuggest that an order parameter based on the quantum-mechanicalexpectation value can be a practically useful numerical observable todetermine critical behavior when there is no well-defined dimensionality
Estimating the performance of heavy impact sound insulation using empirical approaches
With an increasing demand for quieter residential environments, impact sound insulation for floating floors is gaining importance. However, existing methods for estimating the performance of heavy impact sound insulation are limited by their inability to comprehensively analyze various types of floating floors, as well as difficulties mathematically determining the input force of the reference source for heavy impacts. To overcome these limitations, this study proposes empirical models for estimating the sound insulation performance of floating floors under heavy impacts. The proposed models are then validated; the model with the highest accuracy exhibits an average estimation error of 2.73 dB at 50–630 Hz. The proposed models exhibit better accuracies than existing analytical models for frequencies below 100 Hz, where the estimation errors of the analytical models were large. Thus, the proposed models may help reduce errors in analytical estimates or when estimating a single numerical quantity for sound insulation rating during the design stage of multifamily housing