Distance Fluctuations Research Articles

The effects of tropical cyclone on the container shipping network: A case study of typhoon Ma-on (2022)

As climate change intensifies, tropical cyclones pose increasing challenges to container shipping networks (CSN). However, research related in this area remains insufficient. In this study, we analyzed the effects of Typhoon Ma-on on the CSN using over 776 million Automatic Identification System (AIS) trajectory signals. Our findings reveal that the typhoon not only altered the network structure of the CSN but also affected the importance of container ports, vessel flow, and travel distance fluctuations along shipping routes. After the typhoon, the recovery of the network’s connectivity and stability, as well as travel time fluctuations, was less robust compared to other aspects. Additionally, the impact ranges for port importance, vessel flow, and travel distance fluctuations were 1,750 km, 500 km, and 2,250 km, respectively, following an inverse distance decay pattern. These findings offer new insights for stakeholders to enhance the effectiveness of disaster prevention and mitigation policies.

Numerical simulation of the first layer printing in electric field-assisted fused filament fabrication for robust unconventionally oriented additive manufacturing

Fused filament fabrication (FFF) stands as a prominent thermoplastic additive manufacturing technique that has a wide range of potential applications. However, the conventional FFF process encounters limitations in unconventional environments, particularly in environments devoid of gravity, such as in extraterrestrial environments or in limited manufacturing conditions where maintaining consistent nozzle standoff distance becomes a challenging task. Fluctuations in nozzle standoff distance lead to inadequate material adhesion and dimensional errors, which results in a high failure rate and prolonged completion time. Thus, the conventional FFF process requires continuous monitoring or human intervention to ensure successful operation. To overcome the shortcomings of the traditional FFF process, an electric field-assisted FFF (E-FFF) process can be utilized to reduce the need for constant supervision and enable reliable production of parts. The E-FFF process integrates a high-voltage power supply unit with a standard FFF printer, generating an electrostatic force between the nozzle and the build plate. The generated electrostatic force can effectively attract the extruded molten polymer toward the build plate, even at a larger z-height of up to 1200 μm in unconventional build platform orientations such as vertical or reverse printing orientation. In this paper, finite element analysis is used to simulate the FFF and E-FFF process. The simulation focuses on the adhesion between extruded material and build plate with extended nozzle standoff distances and predicts the minimum voltage required to achieve a good material adhesion in unconventional orientations for the E-FFF process. The simulation model demonstrated its efficacy by estimating the minimum required voltage levels necessary for successful printing within the E-FFF process across a range of nozzle standoff distances in unconventional orientations.

Melting of binary mixtures

The melting process of two-dimensional binary mixtures is studied using the Langevin simulation method. The melting point of each component in a binary mixture is determined by the local relative interparticle distance fluctuation method. The results show that, compared with the monodisperse system, the components of the binary mixture exhibit a multi-step melting characteristic. Further, the melting process of binary mixtures is found to depend on the mixing ratio and charge ratio. It is shown that particle hopping motion plays a key role in understanding melting in binary mixtures.

Support effects on conical intersections of Jahn-Teller fluxional metal clusters on the sub-nanoscale.

The concept of fluxionality has been invoked to explain the enhanced catalytic properties of atomically precise metal clusters of subnanometer size. Cu3 isolated in the gas phase is a classical case of a fluxional metal cluster where a conical intersection leads to a Jahn-Teller (JT) distortion resulting in a potential energy landscape with close-lying multiminima and, ultimately, fluxional behavior. In spite of the role of conical intersections in the (photo)stability and (photo)catalytic properties of surface-supported atomic metal clusters, they have been largely unexplored. In this work, by applying a high-level multi-reference ab initio method aided with dispersion corrections, we analyze support effects on the conical intersection of Cu3 considering benzene as a model support molecule of carbon-based surfaces. We verify that the region around the conical intersection and the associated Jahn-Teller (JT) distortion is very slightly perturbed by the support when the Cu3 cluster approaches it in a parallel orientation: Two electronic states remain degenerate for a structure with C3 symmetry consistent with the D3h symmetry of unsupported Cu3 at the conical intersection. It extends over a one-dimensional seam that characterizes a physisorption minimum of the Cu3-benzene complex. The fluxionality of the Cu3 cluster, reflected in large fluctuations of relaxed Cu-Cu distances as a function of the active JT mode, is kept unperturbed upon complexation with benzene as well. In stark contrast, for the energetically favored perpendicular orientation of the Cu3 plane to the benzene ring plane, the conical intersection (CI) is located 12 100 cm-1 (∼1.5 eV) above the chemisorption minimum, with the fluxionality being kept at the CI's nearby and lost at the chemisorption well. The first excited state at the perpendicular orientation has a deep well (>4000 cm-1), being energetically closer to the CI. The transition dipole moment between ground and excited states has a significant magnitude, suggesting that the excited state can be observed through direct photo-excitation from the ground state. Besides demonstrating that the identity of an isolated Jahn-Teller metal cluster can be preserved against support effects at a physisorption state and lifted out at a chemisorption state, our results indicate that a correlation exists between conical intersection topography and fluxionality in the metal cluster's Cu-Cu motifs.

Measuring cosmic bulk flow with Pantheon catalogue in perturbed f(R) gravity

ABSTRACT This study investigates the cosmic bulk flow through an analysis of luminosity distance variations in a perturbed Friedmann universe governed by f(R) gravity. The Hubble parameter, derived from perturbed Friedmann equations capturing intrinsic temporal fluctuations, is crucial. Redshift tomography is used to analyse observational data from the Pantheon catalogue from 0.015 to z < 2.3. Our objective is to constrain the cosmic bulk flow’s direction and magnitude within this redshift range. At low redshifts (z < 0.06), the predominant bulk flow aligns with the dominating supercluster in the corresponding range, maintaining a relatively constant magnitude, consistent with Lambda cold dark matter (ΛCDM) model predictions. A shift towards (l, b) = (290 ± 21, 15 ± 20) with $v_{\mathrm{bulk}} = 774 \pm 83 \, \mathrm{km\, s}^{-1}$ occurs between 0.06 < z < 0.1, coinciding with the cosmic microwave background dipole. For 0.1 < z < 0.2, the bulk flow shifts to (l, b) = (270 ± 21, 25 ± 20) with $v_{\mathrm{bulk}} = 903 \pm 102 \, \mathrm{km\, s}^{-1}$, supporting Kashlinsky et al.’s result. Beyond z > 0.2, the bulk flow’s magnitude exceeds $1000 \, \mathrm{km\, s}^{-1}$, deviating from ΛCDM model expectations. Our findings suggest that matter density oscillations under f(R) gravity exhibit ΛCDM model properties at low redshifts. However, the microwave background anisotropy shows noticeable fluctuations at higher redshifts, validating prior findings of strong cosmic bulk flows at these scales.

Decrypting Allostery in Membrane-Bound K-Ras4B Using Complementary In Silico Approaches Based on Unbiased Molecular Dynamics Simulations.

Protein functions are dynamically regulated by allostery, which enables conformational communication even between faraway residues, and expresses itself in many forms, akin to different "languages": allosteric control pathways predominating in an unperturbed protein are often unintuitively reshaped whenever biochemical perturbations arise (e.g., mutations). To accurately model allostery, unbiased molecular dynamics (MD) simulations require integration with a reliable method able to, e.g., detect incipient allosteric changes or likely perturbation pathways; this is because allostery can operate at longer time scales than those accessible by plain MD. Such methods are typically applied singularly, but we here argue their joint application─as a "multilingual" approach─could work significantly better. We successfully prove this through unbiased MD simulations (∼100 μs) of the widely studied, allosterically active oncotarget K-Ras4B, solvated and embedded in a phospholipid membrane, from which we decrypt allostery using four showcase "languages": Distance Fluctuation analysis and the Shortest Path Map capture allosteric hotspots at equilibrium; Anisotropic Thermal Diffusion and Dynamical Non-Equilibrium MD simulations assess perturbations upon, respectively, either superheating or hydrolyzing the GTP that oncogenically activates K-Ras4B. Chosen "languages" work synergistically, providing an articulate, mutually coherent, experimentally consistent picture of K-Ras4B allostery, whereby distinct traits emerge at equilibrium and upon GTP cleavage. At equilibrium, combined evidence confirms prominent allosteric communication from the membrane-embedded hypervariable region, through a hub comprising helix α5 and sheet β5, and up to the active site, encompassing allosteric "switches" I and II (marginally), and two proposed pockets. Upon GTP cleavage, allosteric perturbations mostly accumulate on the switches and documented interfaces.

Pathogenic Networks and Natural Thinning of Stands

In pine cultures on an area of 0.66 hectares, 345 trees that had fallen away by the age of 59 and 1436 pathogenic zones were studied using biolocation. The cells of their networks have sides with distance fluctuations of 69-845 cm, and north-south and west-east in the Hartman network, the distances between the zones are 360±5 and 390±6 cm, and in the Kurri network 262±2.7 and 295±3 cm. The cells can be triangular, and one side is longer than the other by a maximum of 4 times. In the Hartman network, 0.55 m zones alternate through two 0.3 m zones. There are three gradations of zone sizes in the Kurri network: 0.33 m, 1 and 2 m. The most important zone is 1 m. To the west-east, it alternates through two zones of 0.33 and 2 m, and in the adjacent row of cells it is always located diagonally, where their number is fixed to four. Hartman zones damage the stem cambium cells within a radius of 29 cm, Kurri zones — 44 cm, as a result, trees gradually die off. For the first time, a “point of early death” with a diameter of 14 cm was found inside these zones, where trees probably died before the age of 10 and therefore left no traces. According to these points, 14 places were found in the rows of crops where, with a high probability, trees simply did not take root. In general, 90.7% of trees fell off in pathogenic zones, in depression belts of other geoactive zones and inside death points, and only 9.3% died due to a small feeding area. This destroys the old paradigm and narratives of forestry with the justification of the fall of trees due to intraspecific competition, which we previously carried out detailed calculations do not confirm, and at an average age competition determines the fall of only about 10% of trees.

Angular width and beam quality of a partially coherent standard Laguerre-Gaussian vortex beam in turbulent plasma.

Analytical formulas for the angular width and propagation factor of a partially coherent standard Laguerre-Gaussian (sLG) vortex beam through anisotropic turbulent plasma were derived based on the extended Huygens-Fresnel integral and the second-order moments of the Wigner distribution function. The evolution properties of the angular width and propagation factor of partially coherent sLG vortex beams propagating in anisotropic turbulent plasma were investigated numerically. The numerical results demonstrate the influence of the source and turbulence parameters on the normalized angular width and normalized propagation factor of the partially coherent sLG vortex beams. It can be observed that in a partially coherent sLG vortex beam with a lower beam order, topological charge, and wavelength, or a higher correlation coefficient of the source plane, and with increasing propagation distance and refractive index fluctuation variance or decreasing anisotropy parameters, the outer and inner scales of the turbulent plasma have a large angular width and propagation factor (i.e.,the beam quality is worse). The results of this study will be beneficial for applications in remote sensing and optical communications.

Study on the building zoning of regional energy planning based on a dynamic programming theory

Building zoning is crucial for regional energy planning. Appropriate building zoning can effectively optimize the peak load, daily load rate and load standard deviation of buildings. However, a clear quantitative standard for building zoning is currently lacking, and zoning methods based on minimum distance or load fluctuation are often employed, which often fail to achieve optimal zoning and energy-saving effects. To clarify building zoning in regional energy planning, this study proposes a dynamic programming approach and employs the analytic hierarchy process (AHP) to improve the zoning method. This is achieved by using the daily load rate, load standard deviation and building distance of each building group as the criterion layer, and assigns each peripheral building group to the appropriate building group. Taking a university campus as an example, this method reduces the peak heating load of 6136.61 kW and the peak cooling load of 15507.88 kW. The standard deviation of heating and cooling load of the building group has been reduced by 1272.53 kW and 2352.54 kW, respectively. Furthermore, the daily load rate of the building has been stabilized, and the staggered peak has been adjusted, resulting in a more uniform distribution frequency of the building load.

The effective beam width of a partially coherent rectangular mul-ti-Gaussian Schell-model vortex beam propagating in a turbulent plasma

Based on the derived analytical formulae for the optical intensity and effective beam width of a partially coherent rectangular multi-Gaussian Schell-model (RMGSM) vortex beam, we analyzed the evolution of the effective beam width of a partially coherent RMGSM vortex beam propagating in an anisotropic turbulent plasma using numerical examples. The numerical results demonstrated that the effective beam widths in the x and y directions were similar. In studies on the influences of the source parameters, one can see that an RMGSM vortex beam with a larger topological charge and beam waist or a smaller correlation coefficient σ evolves into a beam with a larger effective beam width. However, the influence of beam order was not evident. In addition, numerical examples proved that the effective beam width increases with increasing propagation distance and refractive index fluctuation variance or decreasing anisotropy parameter , outer scale , and inner scale . This study's results will be beneficial for applications in free-space optical communications.

First Report on Real-World Outcomes with Evoked Compound Action Potential (ECAP)-Controlled Closed-Loop Spinal Cord Stimulation for Treatment of Chronic Pain.

A novel closed-loop spinal cord stimulation (SCS) system has recently been approved for use which records evoked compound action potentials (ECAPs) from the spinal cord and utilizes these recordings to automatically adjust the stimulation strength in real time. It automatically compensates for fluctuations in distance between the epidural leads and the spinal cord by maintaining the neural response (ECAP) at a determined target level. This data collection was principally designed to evaluate the performance of this first closed-loop SCS system in a 'real-world' setting under normal conditions of use in a single European center. In this prospective, single-center observational data collection, 22 patients were recruited at the outpatient pain clinic of the St. Antonius Hospital. All candidates were suffering from chronic pain in the trunk and/or limbs due to PSPS type 2 (persistent spinal pain syndrome). As standard of care, follow-up visits were completed at 3months, 6months, and 12months post-device activation. Patient-reported outcome data (pain intensity, patient satisfaction) and electrophysiological and device data (ECAP amplitude, conduction velocity, current output, pulse width, frequency, usage), and patient interaction with their controller were collected at baseline and during standard of care follow-up visits. Significant decreases in pain intensity for overall back or leg pain scores (verbal numerical rating score=VNRS) were observed between baseline [mean±SEM (standard error of the mean); n=22; 8.4±0.2)], 3months (n=12; 1.9±0.5), 6months (n=16; 2.6±0.5), and 12months (n=20; 2.0±0.5), with 85.0% of the patients being satisfied at 12months. Additionally, no significant differences in average pain relief at 3months and 12months between the real-world data (77.2%; 76.8%) and the AVALON (71.2%; 73.6%) and EVOKE (78.1%; 76.7%) studies were observed. These initial 'real-world' data on ECAP-controlled, closed-loop SCS in a real-world clinical setting appear to be promising, as they provide novel insights of the beneficial effect of ECAP-controlled, closed-loop SCS in a real-world setting. The presented results demonstrate a noteworthy maintenance of pain relief over 12months and corroborate the outcomes observed in the AVALON prospective, multicenter, single-arm study and the EVOKE double-blind, multicenter, randomized controlled trial. The data collection is registered on the International Clinical Trials Registry Platform (Trial NL7889).

Robustness of Wireless Power Transfer Systems with Parity-Time Symmetry and Asymmetry

Recently, wireless power transfer (WPT) technology has attracted much attention and shown rapid development. However, a fundamental challenge emerges in practical applications: how to achieve robust power transfer against the variation of operating conditions, such as the fluctuation of transfer distance, as well as the relative orientation of resonant coils. In this article, we theoretically propose and experimentally demonstrate that the robustness of a parity-time (PT) asymmetric system with unbalanced gain-loss working in a weak coupling region can be improved significantly, compared with that of a PT-symmetric system with balanced gain-loss working in a strong coupling region under the premise that the system works at a fixed optimal frequency. A pure real mode known as bound state in the continuum (BIC) in the weak coupling region of the PT-asymmetric system is adopted to ensure the high efficiency and stability of the WPT and break the limitations of balanced gain-loss of the PT-symmetric system. The better robustness performance originates from the orthogonal state with a pure real eigenmode embedded in the weak coupling region. Further experiments also verify that the PT-asymmetric system can achieve higher efficiency than that of the PT-symmetric system. In addition, we discuss the performance of the WPT system based on the theories of coupled mode theory (CMT) and circuit theory (CT); the BIC in the framework of CMT and a perfect impedance matching condition in the framework of CT for efficient power transfer are consistent. We also conducted power experimental verification of 30 watts, and found the efficiency between the coils can reach over 90% in dynamic scenarios, which meets expectations. The presented framework extends the field of non-Hermitian physics, bridges the gap between the non-ideal PT-symmetric system and a practical engineering application, and introduces a novel WPT mechanism for flexible application scenarios. Our results could provide instructive significance for practical applications of the WPT system in the long term.

Approaching the Intrinsic Properties of Moiré Structures Using Atomic Force Microscopy Ironing.

Stacking monolayers of transition metal dichalcogenides (TMDs) has led to the discovery of a plethora of new exotic phenomena, resulting from moiré pattern formation. Due to the atomic thickness and high surface-to-volume ratio of heterostructures, the interfaces play a crucial role. Fluctuations in the interlayer distance affect interlayer coupling and moiré effects. Therefore, to access the intrinsic properties of the TMD stack, it is essential to obtain a clean and uniform interface between the layers. Here, we show that this is achieved by ironing with the tip of an atomic force microscope. This post-stacking procedure dramatically improves the homogeneity of the interfaces, which is reflected in the optical response of the interlayer exciton. We demonstrate that ironing improves the layer coupling, enhancing moiré effects and reducing disorder. This is crucial for the investigation of TMD heterostructure physics, which currently suffers from low reproducibility.

Abnormal Electromagnetic Wave Detection Method Before Earthquake Based on Feature Extraction of Radio Frequency I/Q Signal

Earthquake is one of the more common natural disasters. At present, it is mainly through the deployment of monitoring stations to provide the earthquake information broadcasting service. Earthquakes are caused by the Earth’s plates pushing against each other. Before an earthquake occurs, the energy gathered by plate compression will produce abnormal electromagnetic radiation due to the compression magnetic effect. The energy detection method of abnormal electromagnetic radiation has been proposed by researchers for a long time. Anomalous electromagnetic radiation is difficult to catch because its energy is very weak. Based on the distributed electromagnetic spectrum detection method, this paper proposes the original radio frequency (RF) I/Q sample data. Combined with I/Q component cumulative distance fluctuation estimation method, abnormal electromagnetic radiation phenomenon is detected. Combined with source location information, magnitude and depth, a prediction model of cumulative distance fluctuation of I/Q component is proposed based on the RF I/Q sample data of electromagnetic spectrum. The results of actual monitoring data show that the prediction model of I/Q component cumulative distance fluctuation estimation can accurately describe the abnormal electromagnetic radiation phenomenon generated by earthquake information above magnitude 6. Combined with a large-scale distributed electromagnetic spectrum detection system, an earthquake prediction system with higher accuracy can be realized.

Universality in conformations and transverse fluctuations of a semi-flexible polymer in a crowded environment.

We study the universal aspects of polymer conformations and transverse fluctuations for a single swollen chain characterized by a contour length L and a persistence length ℓp in two dimensions (2D) and three dimensions (3D) in the bulk, as well as in the presence of excluded volume (EV) particles of different sizes occupying different area/volume fractions. In the absence of the EV particles, we extend the previously established universal scaling relations in 2D [Huang et al., J. Chem. 140, 214902 (2014)] to include 3D and demonstrate that the scaled end-to-end distance ⟨RN2⟩/(2Lℓp) and the scaled transverse fluctuation ⟨l⊥2⟩/L as a function of L/ℓp collapse onto the same master curve, where ⟨RN2⟩ and ⟨l⊥2⟩ are the mean-square end-to-end distance and transverse fluctuations. However, unlike in 2D, where the Gaussian regime is absent due to the extreme dominance of the EV interaction, we find that the Gaussian regime is present, albeit very narrow in 3D. The scaled transverse fluctuation in the limit L/ℓp ≪ 1 is independent of the physical dimension and scales as ⟨l⊥2⟩/L∼(L/ℓp)ζ-1, where ζ = 1.5 is the roughening exponent. For L/ℓp ≫ 1, the scaled fluctuation scales as ⟨l⊥2⟩/L∼(L/ℓp)ν-1, where ν is the Flory exponent for the corresponding spatial dimension (ν2D = 0.75 and ν3D = 0.58). When EV particles of different sizes for different area or volume fractions are added into 2D and 3D systems, our results indicate that the crowding density either does not or does only weakly affect the universal scaling relations. We discuss the implications of these results in living matter by showing the experimental result for a dsDNA on the master plot.

Analysis of the influence of detouring obstacle avoidance behavior on unidirectional flow

A pedestrian’s active obstacle avoidance behavior has an important impact on crowd safety in heterogeneous crowd movements, but how it affects the movement of individuals and crowd is not yet clear. This study proposes a detour anisotropic social force model (DASFM) that considers active obstacle avoidance behavior for future collision prediction. DASFM prioritizes moving obstacle pedestrians based on velocity obstacle (VO) and combines the anisotropic social force model (ASFM) to achieve the dynamic process of pedestrian active obstacle avoidance behavior. The results show that DASFM enables individuals to safely overtake while avoiding fluctuations in pedestrian speed and distance between pedestrians. The model improved abnormal “strip group” crowd aggregation, individual jostling, and congestion found in other models. It has effective performance in spatial distribution, trajectory, density evolution, and time consumption of crowd movement in unidirectional flow under open conditions. The fundamental diagram generated by DASFM in unidirectional flow under periodic boundary conditions tends to be consistent with the observations and experimental results of other researchers. Instantaneous flow analysis shows that overtaking behavior alleviates local congestion in the low-density crowd and promotes the slow flow of the high-density crowd. However, overtaking behavior also exacerbates the stop-and-go waves of the high-density crowd, posing a threat to crowd safety. This study not only effectively realizes the simulation of overtaking behavior among individuals and crowds, but also discovers the impact patterns of overtaking behavior on low- or high-density crowd. Therefore, measures should be taken to control individual overtaking behavior in high-density crowd to prevent the production of stop-and-go waves.

Effect of Proton Irradiation on Zr/Nb Nanoscale Multilayer Structure and Properties

The effect of proton irradiation on the structure, phase composition, defect state and nanohardness of Zr/Nb nanoscale multilayer coatings was investigated. Preservation of the Zr/Nb layered structure with 50 and 100 nm thick layers, was observed after irradiation with protons at 1720 keV energy and 3.4 × 1015, 8.6 × 1015 and 3.4 × 1016 ions/cm2 fluences, and the interfaces remained incoherent. In the Zr/Nb nanoscale multilayer coatings with individual layer thicknesses of 10 and 25 nm, there were insignificant fluctuations in interplanar distance, which were influenced by changes in irradiation fluence, and the interfaces were partially destroyed and became semicoherent. Changing irradiation fluence in the investigated ranges led to a decrease in the nanohardness of the Zr/Nb nanoscale multilayer coatings with individual layer thicknesses of 10–50 nm. Variable-energy positron Doppler broadening analysis revealed that these changes are primarily caused by peculiarities of the localization and accumulation of the embedded ions and do not cause a significant increase in the S-parameters of Zr/Nb nanoscale multilayer coatings with a layer thickness less than 100 nm.

New experimental evidence for pervasive dynamics in proteins.

There is ample computational, but only sparse experimental data suggesting that pico-ns motions with 1 Å amplitude are pervasive in proteins in solution. Such motions, if present in reality, must deeply affect protein function and protein entropy. Several NMR relaxation experiments have provided insights into motions of proteins in solution, but they primarily report on azimuthal angle variations of vectors of covalently-linked atoms. As such, these measurements are not sensitive to distance fluctuations, and cannot but under-represent the dynamical properties of proteins. Here we analyze a novel NMR relaxation experiment to measure amide proton transverse relaxation rates in uniformly 15 N labeled proteins, and present results for protein domain GB1 at 283 and 303 K. These relaxation rates depend on fluctuations of dipolar interactions between 1 HN and many nearby protons on both the backbone and sidechains. Importantly, they also report on fluctuations in the distances between these protons. We obtained a large mismatch between rates computed from the crystal structure of GB1 and the experimental rates. But when the relaxation rates were calculated from a 200 ns molecular dynamics trajectory using a novel program suite, we obtained a substantial improvement in the correspondence of experimental and theoretical rates. As such, this work provides novel experimental evidence of widespread motions in proteins. Since the improvements are substantial, but not sufficient, this approach may also present a new benchmark to help improve the theoretical forcefields underlying the molecular dynamics calculations.

Video-based pedestrian grouping model considering long-span space in a big hall

Pedestrian group detection is a challenging but significant issue in pedestrian flow control and public safety management. To address the issue that most conventional pedestrian grouping models (PGMs) can only identify a pedestrian group at a limited distance of less than 2 m, this study extended the pedestrian distance constraint of conventional PGMs with a reconstruction of the normal group detection criterion and development of a novel group detection criterion suitable for long-span space. To measure the movement behavior similarity with normal distance, five necessary constraints: velocity difference, moving direction offset, distance limitation, distance fluctuation, and group-keeping duration were studied quantitatively to form the criterion to detect normal groups. Meanwhile, a long-span group detection criterion was proposed with extended distance and direction consistency constraints. Therefore, this study proposed an improved PGM that considers long-span spaces (PGMLS). In the PGMLS workflow, the MMTrack algorithm was used to obtain pedestrian trajectories. A difference measurement method based on sequential pattern analysis (SPA) was adopted to analyze the velocity similarity of pedestrians. To validate the proposed grouping model, experiments based on pedestrian movement videos in the exit hall of the Shanghai Hongqiao International Airport were conducted. The results indicate that the proposed model can detect both normal and widely separated pedestrian groups, with a long span range of 2–12 m.

Cooperative mechanics of PR65 scaffold underlies the allosteric regulation of the phosphatase PP2A

PR65, a horseshoe-shaped scaffold composed of 15 HEAT (observed in Huntingtin, elongation factor 3, protein phosphatase 2A, and the yeast kinase TOR1) repeats, forms, together with catalytic and regulatory subunits, the heterotrimeric protein phosphatase PP2A. We examined the role of PR65 in enabling PP2A enzymatic activity with computations at various levels of complexity, including hybrid approaches that combine full-atomic and elastic network models. Our study points to the high flexibility of this scaffold allowing for end-to-end distance fluctuations of 40-50Å between compact and extended conformations. Notably, the intrinsic dynamics of PR65 facilitates complexation with the catalytic subunit and is retained in the PP2A complex enabling PR65 to engage the two domains of the catalytic subunit and provide the mechanical framework for enzymatic activity, with support from the regulatory subunit. In particular, the intra-repeat coils at the C-terminal arm play an important role in allosterically mediating the collective dynamics of PP2A, pointing to target sites for modulating PR65 function.