Preda A.T.Anghel D.-V.Dolineanu M.
5页查看更多>>摘要：© 2022 Elsevier B.V.The parity violation in nuclear reactions led to the discovery of the new class of toroidal multipoles. Since then, it was observed that toroidal multipoles are present in the electromagnetic structure of systems at all scales, from elementary particles, to solid state systems and metamaterials. The toroidal dipole T (the lowest order multipole) is the most common. In quantum systems, this corresponds to the toroidal dipole operator Tˆ, with the projections Tˆi (i=1,2,3) on the coordinate axes. Here we analyze a quantum particle in a system with cylindrical symmetry, which is a typical system in which toroidal moments appear. We find the expressions for the Hamiltonian, momenta, and toroidal dipole operators in adequate curvilinear coordinates, which allow us to find analytical expressions for the eigenfunctions of the momentum operators. While the toroidal dipole is hermitian, it is not self-adjoint, but in the new set of coordinates the operator Tˆ3 splits into two components, one of which is (only) hermitian, whereas the other one is self-adjoint. The self-adjoint component is the one that is physically significant and represents an observable. Furthermore, we numerically diagonalize the Hamiltonian and the toroidal dipole operator and find their eigenfunctions and eigenvalues. We write the partition function and calculate the thermodynamic quantities for a system of ideal particles on a torus. Besides proving that the toroidal dipole is self-adjoint and therefore an observable, such systems open up the possibility of making metamaterials that exploit the quantization and the quantum properties of the toroidal dipoles.
原文链接:
NSTL
Syed A.Panchagnula M.V.Thampi S.P.
5页查看更多>>摘要：© 2022 Elsevier B.V.We study the dynamics of human crowds using agent-based modelling and study the proposition that random motion of agents can be transitioned to collective motion by controlling individual agent dynamics. Specifically, we investigate and characterize the nature of transitions from collective motion to disorderly motion and vice versa. Our results show that collective motion in crowds arise under certain conditions of coordination as well as individual motivation. We show a regime map when first order phase transition from disordered to orderly crowd motion is observed as the coordination increases. Similarly, we show that for a constant coordination coefficient, as the individual motivation increases, a second order transition is observed. Therefore, for every value of coordination coefficient, we identify a critical value of motive force which is required for the crowd to self-organize by smoothly transitioning into orderly motion.
原文链接:- NSTL
Navidad Maeso D.Patriarca M.Heinsalu E.
5页查看更多>>摘要：© 2022 Elsevier B.V.We investigate how initial and boundary conditions influence the competition dynamics and outcome in dispersal-structured populations. The study is carried out through numerical modeling of the heterogeneous Brownian bugs model, in which individuals are characterized by diversified diffusion coefficients and compete for resources within a finite interaction range. We observed that if instead of being distributed randomly across the domain the population is initially localized within a small region, the dynamics and the stationary state of the system differ significantly. The outcome of the natural selection is determined by different competition processes, fluctuations, and spreading of the organisms.
原文链接:- NSTL
Xu D.Qian Y.Da C.Zeng J....
5页查看更多>>摘要：© 2022 Elsevier B.V.In this paper, a bidirectional quasi-moving block cellular automaton model for single-track railways is proposed to simulate the impact of quasi-moving block on the passing capacity of single track railway. The rules of train departure, meeting, entering the station and running in the section are formulated and the Naqu–Lhasa section of the Qinghai–Tibet Railway is taken as an example for simulation. The results show that, under the quasi moving block, with the changes of the mixed ratio and stop time of freight train, the passing capacity is improved compared with the currently adopted automatic inter-station block. Besides, it is found that the passing capacity is the largest under equal station spacing conditions, indicating that the distance between stations should be minimized in the preliminary line design.
原文链接:- NSTL
Phillips J.C.Moret M.A.Zebende G.F.Chow C.C....
5页查看更多>>摘要：© 2022The novel coronavirus SARS CoV-2 responsible for the COVID-19 pandemic and SARS CoV-1 responsible for the SARS epidemic of 2002-2003 share an ancestor yet evolved to have much different transmissibility and global impact 1. A previously developed thermodynamic model of protein conformations hypothesized that SARS CoV-2 is very close to a new thermodynamic critical point, which makes it highly infectious but also easily displaced by a spike-based vaccine because there is a tradeoff between transmissibility and robustness 2. The model identified a small cluster of four key mutations of SARS CoV-2 that predicts much stronger viral attachment and viral spreading compared to SARS CoV-1. Here we apply the model to the SARS-CoV-2 variants Alpha (B.1.1.7), Beta (B.1.351), Gamma (P.1) and Delta (B.1.617.2)3 and predict, using no free parameters, how the new mutations will not diminish the effectiveness of current spike based vaccines and may even further enhance infectiousness by augmenting the binding ability of the virus.
原文链接:- NSTL
Nasirimoghadam S.Aliabadi R.Moradi M.
5页查看更多>>摘要：© 2022 Elsevier B.V.This study investigated the nematic phase structures of hard uniaxial ellipsoidal rods having a short axis of 2b, a long axis of 2a, and the elongations k=[Formula presented]=3 and 5 in strongly confined pores via the density functional theory with Zwanzig and hyper-netted-chain approximations. By increasing the density, the number of planar nematic layers gradually rise without any phase transition. These layering phenomena occurred between two biaxial structures with different numbers of planar layers in which the layers’ spacing was approximately 2b.
原文链接:- NSTL
Zhang Y.Shang K.-K.Wang C.-J.Feng M....
5页查看更多>>摘要：© 2022 Elsevier B.V.For computational social scientists, cascade size prediction and fake news detection are two primary problems in news diffusion or computational communication research. Previous studies predict news diffusion via peeking the social process (temporal structure) data in the initial stage, which is summarized as Peeking strategy. However, the accuracy of Peeking strategy for cascade size prediction still should be improved, and the advantage or limitation of Peeking strategy for fake news detection has not been fully investigated. To predict cascade size and detect fake news, we adopt Peeking strategy based on well-known machine learning algorithms. Our results show that Peeking strategy can effectively improve the accuracy of cascade size prediction. Meanwhile, we can peek into a smaller time window to achieve a higher performance in predicting the cascade size compared with previous methods. Nevertheless, we find that Peeking strategy with network structures fails in significantly improving the performance of fake news detection. Finally, we argue that cascade structure properties can aid in prediction of cascade size, but not for the fake news detection.
原文链接:- NSTL
