arXiv subjects

Xiaoting Yang

Publications and source records attributed to Xiaoting Yang.

5 recordsLinked to original sources

arXiv2025

Collaborative governance of cyber violence: A two-phase, multi-scenario four-party evolutionary game and SBI1I2R public opinion dissemination

Cyber violence severely disrupts public order in both cyberspace and the real world. Existing studies have gradually advocated collaborative governance but rely on macro-level theoretical analyses. This study integrates micro- and macro-level perspectives to propose a two-stage, multi-scenario governance mechanism for cyber violence. In the first phase, a multi-scenario evolutionary game model with four parties involved in cyber violence was developed based on evolutionary game theory. Matlab simulations show that under strong government regulation, moderate levels of punishment implemented by the government against the online media that adopt misguidance strategies can achieve the most desirable stable state. In the second phase, the role of bystanders was introduced by integrating communication dynamics theory, and emotional factors were considered alongside game strategies. This led to the development of a new SBI1I2R model for public opinion dissemination in cyber violence. Netlogo simulations found that increasing the "correct guidance" strategy by the online media reduces the influence of cyber violence supporters and the time it takes for their nodes to drop to zero, but does not significantly shorten the time for the peak to occur. Comparatively, collaborative intervention between the online media and the government was most effective in curbing public opinion, followed by the government's independent "strong regulation." Relying solely on the online media's "correct guidance" produced the weakest effect. Finally, this mechanism was applied to a case study, and a multi-stage, multi-scenario analysis based on life cycle theory enhanced its practical applicability.

cs.MA↗

arXiv2023

General integrated rate law for complex self-assembly reactions reveals the mechanism of amyloid-beta co-aggregation

Analyzing kinetic experiments on protein aggregation using integrated rate laws has led to numerous advances in our understanding of the fundamental chemical mechanisms behind amyloidogenic disorders such as Alzheimer's and Parkinson's diseases. However, the description of biologically relevant processes may require rate equations that are too complex to solve using existing methods, hindering mechanistic insights into these processes. An example of significance is co-aggregation in environments containing multiple amyloid-beta (Abeta) peptide alloforms, which may play a crucial role in the biochemistry of Alzheimer's disease but whose mechanism is still poorly understood. Here, we use the mathematics of symmetry to derive a general integrated rate law valid for most plausible linear self-assembly reactions. We use it in conjunction with experimental data to determine the mechanism of co-aggregation of the most physiologically abundant Abeta alloforms: Abeta42, Abeta40, Abeta38 and Abeta37 peptides. We find that Abeta42 fibril surfaces catalyze the formation of co-oligomers, which accelerate new Abeta40, Abeta38 and Abeta37 fibril formation whilst inhibiting secondary nucleation of new Abeta42 fibrils. The simplicity, accuracy and broad applicability of our general integrated rate law will enable kinetic analysis of more complex filamentous self-assembly reactions, both with and without co-aggregation.

physics.chem-ph↗

arXiv2021

Mid-depth Ocean Stratification: Southern Ocean eddies vs interior vertical diffusivity

The mid-depth ocean stratification was fitted by Munk (1966) to an exponential profile and shown to be consistent with a vertical advective-diffusive balance. However, tracer release experiments show that vertical diffusivity in the mid-depth ocean is an order of magnitude too small to explain the observed 1 km exponential scale. Alternative mechanisms suggested that the overturning is mostly adiabatic, that interior diapycnal upwelling is negligible, and that nearly all mid-depth water upwells adiabatically in the Southern Ocean (SO). In this picture, SO eddies and wind set isopycnal slopes in the SO and therefore determine a non-vanishing mid-depth interior stratification even in the adiabatic limit. The effect of SO eddies on SO isopycnal slopes can be understood via either a marginal criticality condition or via a near-vanishing residual overturning conditions in the adiabatic limit. We examine the role of SO eddies vs interior mixing in setting the mid-depth stratification by using eddy-permitting numerical simulations, in which we artificially change the diapycnal mixing only away from the SO. We find that SO isopycnal slopes change in response to changes of the interior diapycnal mixing even when the wind forcing is constant, consistent with previous studies. However, in the limit of small interior mixing, the interior stratification is far from exponential, suggesting that SO processes alone do not lead to the observed stratification. The results suggest that while SO eddies contribute to the non-vanishing mid-depth interior stratification, the exponential shape of the stratification must also involve interior diapycnal mixing. Both SO eddies and interior diapycnal mixing are therefore important in determining the interior mid-depth exponential stratification.

physics.ao-ph↗

arXiv2019

Reconciling the Observed Mid-Depth Exponential Ocean Stratification with Weak Interior Mixing and Southern Ocean Dynamics via Boundary-Intensified Mixing

Munk (1966) showed that the deep (1000-3000 m) vertical temperature profile is consistent with a one-dimensional vertical advection-diffusion balance, with a constant upwelling and an interior diapycnal diffusivity of $\mathcal{O}(10^{-4})$ m$^{2}$ s$^{-1}$. However, typical observed diffusivities in the interior are $\mathcal{O}(10^{-5})$ m$^{2}$ s$^{-1}$. Recent work suggested that the deep stratification is set by Southern Ocean (SO) isopycnal slopes, fixed by SO eddies, that communicate the surface outcrop positions to the deep ocean. It is shown here, using an idealized ocean general circulation model, that SO eddies alone cannot lead to the observed exponential temperature profile, and that interior mixing must contribute. Strong diapycnal mixing concentrated near the ocean boundaries is shown to be balanced locally by upwelling. A one-dimensional Munk-like balance in these boundary mixing areas, although with much larger mixing and upwelling, leads to an exponential deep temperature stratification, which propagates via isopycnal mixing to the ocean interior. The exponential profile is robust to vertical variations in the vertical velocity, and persists despite the observed weak interior diapycnal mixing. Southern Ocean eddies link the surface water mass transformation by air-sea fluxes with the deep stratification, but the eddies do not determine the stratification itself. These results reconcile the observed exponential interior deep temperature stratification, the weak diapycnal diffusivity observed in tracer release experiments, and the role of Southern Ocean dynamics.

physics.ao-ph↗

arXiv2016

A general reaction network unifies the aggregation behaviour of the A$\beta$42 peptide and its variants

The amyloid $\beta$ peptide (A$\beta$42), whose aggregation is associated with Alzheimer's disease, is an amphiphatic peptide with a high propensity to self-assemble. A$\beta$42 has a net negative charge at physiological pH and modulations of intermolecular electrostatic interactions can significantly alter its aggregation behaviour. Variations in sequence and solution conditions lead to varied macroscopic behaviour, often resulting in a number of different mechanistic explanations for the aggregation of these closely related systems. Here we alter the electrostatic interactions governing the fibril aggregation kinetics by varying the ionic strength over an order of magnitude, which allows us to sample the space of different reaction mechanisms, and develop a minimal reaction network that explains the experimental kinetics under all the different conditions. We find that an increase in the ionic strength leads to an increased rate of surface catalysed nucleation over fragmentation and eventually to a saturation of this nucleation process. More generally, this reaction network connects previously separate systems, such as mutants of A$\beta$42 and the wild type, on a continuous mechanistic landscape, thereby providing a unified picture of the aggregation mechanism of A$\beta$42 and the means of directly comparing the effects of intrinsic modifications of the peptide to those of simple electrostatic shielding.

q-bio.MN↗