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1
Wang, Yang, Shih-to Fei, Young-Moo Byun, Paul E. Lammert, Vincent H. Crespi, Ayusman Sen, and Thomas E. Mallouk. "Dynamic Interactions between Fast Microscale Rotors." Journal of the American Chemical Society 131, no. 29 (July 29, 2009): 9926–27. http://dx.doi.org/10.1021/ja904827j.
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Mowbray, D. J., Sangwoo Chung, Z. L. Mišković, F. O. Goodman, and You-Nian Wang. "Dynamic interactions of fast ions with carbon nanotubes." Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms 230, no. 1-4 (April 2005): 142–47. http://dx.doi.org/10.1016/j.nimb.2004.12.032.
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Chawla, D., E. D. Lumer, and K. J. Friston. "Relating Macroscopic Measures of Brain Activity to Fast, Dynamic Neuronal Interactions." Neural Computation 12, no. 12 (December 1, 2000): 2805–21. http://dx.doi.org/10.1162/089976600300014737.
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In this article we used biologically plausible simulations of coupled neuronal populations to address the relationship between phasic and fast coherent neuronal interactions and macroscopic measures of activity that are integrated over time, such as the BOLD response in functional magnetic resonance imaging. Event-related, dynamic correlations were assessed using joint peristimulus time histograms and, in particular, the mutual information between stimulus-induced transients in two populations. This mutual information can be considered as an index of functional connectivity. Our simulations showed that functional connectivity or dynamic integration between two populations increases with mean background activity and stimulus-related rate modulation. Furthermore, as the background activity increases, the populations become increasingly sensitive to the intensity of the stimulus in terms of a predisposition to transient phase locking. This reflects an interaction between background activity and stimulus intensity in producing dynamic correlations, in that background activity augments stimulus-induced coherence modulation. This is interesting from a computational perspective because background activity establishes a context that may have a profound effect on event-related interactions or functional connectivity between neuronal populations. Finally, total firing rates, which subsume both background activity and stimulus-related rate modulation, were almost linearly related to the expression of dynamic correlations over large ranges of activities. These observations show that under the assumptions implicit in our model, rate-specific metrics based on rate or coherence modulation may be different perspectives on the same underlying dynamics. This suggests that activity (averaged over all peristimulus times), as measured in neuroimaging, may be tightly coupled to the expression of dynamic correlations.
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Chung, Sangwoo, D. J. Mowbray, Z. L. Mišković, F. O. Goodman, and You-Nian Wang. "Dynamic interactions of fast ions with multiwalled carbon nanotubes." Radiation Physics and Chemistry 76, no. 3 (March 2007): 524–28. http://dx.doi.org/10.1016/j.radphyschem.2005.09.020.
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Fiore, Andrew M., and James W. Swan. "Fast Stokesian dynamics." Journal of Fluid Mechanics 878 (September 17, 2019): 544–97. http://dx.doi.org/10.1017/jfm.2019.640.
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We present a new method for large scale dynamic simulation of colloidal particles with hydrodynamic interactions and Brownian forces, which we call fast Stokesian dynamics (FSD). The approach for modelling the hydrodynamic interactions between particles is based on the Stokesian dynamics (SD) algorithm (J. Fluid Mech., vol. 448, 2001, pp. 115–146), which decomposes the interactions into near-field (short-ranged, pairwise additive and diverging) and far-field (long-ranged many-body) contributions. In FSD, the standard system of linear equations for SD is reformulated using a single saddle point matrix. We show that this reformulation is generalizable to a host of particular simulation methods enabling the self-consistent inclusion of a wide range of constraints, geometries and physics in the SD simulation scheme. Importantly for fast, large scale simulations, we show that the saddle point equation is solved very efficiently by iterative methods for which novel preconditioners are derived. In contrast to existing approaches to accelerating SD algorithms, the FSD algorithm avoids explicit inversion of ill-conditioned hydrodynamic operators without adequate preconditioning, which drastically reduces computation time. Furthermore, the FSD formulation is combined with advanced sampling techniques in order to rapidly generate the stochastic forces required for Brownian motion. Specifically, we adopt the standard approach of decomposing the stochastic forces into near-field and far-field parts. The near-field Brownian force is readily computed using an iterative Krylov subspace method, for which a novel preconditioner is developed, while the far-field Brownian force is efficiently computed by linearly transforming those forces into a fluctuating velocity field, computed easily using the positively split Ewald approach (J. Chem. Phys., vol. 146, 2017, 124116). The resultant effect of this field on the particle motion is determined through solution of a system of linear equations using the same saddle point matrix used for deterministic calculations. Thus, this calculation is also very efficient. Additionally, application of the saddle point formulation to develop high-resolution hydrodynamic models from constrained collections of particles (similar to the immersed boundary method) is demonstrated and the convergence of such models is discussed in detail. Finally, an optimized graphics processing unit implementation of FSD for mono-disperse spherical particles is used to demonstrated performance and accuracy of dynamic simulations of $O(10^{5})$ particles, and an open source plugin for the HOOMD-blue suite of molecular dynamics software is included in the supplementary material.
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Ashwin, S. S., Tadasu Nozaki, Kazuhiro Maeshima, and Masaki Sasai. "Organization of fast and slow chromatin revealed by single-nucleosome dynamics." Proceedings of the National Academy of Sciences 116, no. 40 (September 16, 2019): 19939–44. http://dx.doi.org/10.1073/pnas.1907342116.
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Understanding chromatin organization and dynamics is important, since they crucially affect DNA functions. In this study, we investigate chromatin dynamics by statistically analyzing single-nucleosome movement in living human cells. Bimodal nature of the mean square displacement distribution of nucleosomes allows for a natural categorization of the nucleosomes as fast and slow. Analyses of the nucleosome–nucleosome correlation functions within these categories along with the density of vibrational modes show that the nucleosomes form dynamically correlated fluid regions (i.e., dynamic domains of fast and slow nucleosomes). Perturbed nucleosome dynamics by global histone acetylation or cohesin inactivation indicate that nucleosome–nucleosome interactions along with tethering of chromatin chains organize nucleosomes into fast and slow dynamic domains. A simple polymer model is introduced, which shows the consistency of this dynamic domain picture. Statistical analyses of single-nucleosome movement provide rich information on how chromatin is dynamically organized in a fluid manner in living cells.
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Li, Zhenhua, and Chao Wang. "Suspension Parameters Optimization of Fast Freight Wagon Based on Low Wheel-Rail Dynamic Interactions." Journal of Physics: Conference Series 2381, no. 1 (December 1, 2022): 012116. http://dx.doi.org/10.1088/1742-6596/2381/1/012116.
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Abstract The dynamic model of fast freight wagon is established to study the effect of key parameters of the freight wagon on dynamic performance. In order to reduce the wheel-rail dynamic interactions, the parameters such as primary suspension stiffness, arm joint stiffness, and joint stiffness of the anti-yaw damper are optimized. The results indicate that the above suspension parameters have an influence on the fast freight wagon’s dynamic performance. Compared with the simulation results of the original parameters, the wheel-rail vertical force is reduced by 10%, and the wheel-rail lateral force is reduced by 42% and 38% respectively under the straight and curve conditions of the empty vehicle. The wheel-rail vertical force is reduced by 10% and 6%, and the wheel-rail lateral force is reduced by 10% and 16% respectively under the straight and curve conditions of the loaded fast freight wagon. The running stability and safety of the fast freight wagon have been improved.
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Aebischer, Kathrin, Lea Marie Becker, Paul Schanda, and Matthias Ernst. "Evaluating the motional timescales contributing to averaged anisotropic interactions in MAS solid-state NMR." Magnetic Resonance 5, no. 1 (June 11, 2024): 69–86. http://dx.doi.org/10.5194/mr-5-69-2024.
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Abstract. Dynamic processes in molecules can occur on a wide range of timescales, and it is important to understand which timescales of motion contribute to different parameters used in dynamics measurements. For spin relaxation, this can easily be understood from the sampling frequencies of the spectral-density function by different relaxation-rate constants. In addition to data from relaxation measurements, determining dynamically averaged anisotropic interactions in magic-angle spinning (MAS) solid-state NMR allows for better quantification of the amplitude of molecular motion. For partially averaged anisotropic interactions, the relevant timescales of motion are not so clearly defined. Whether the averaging depends on the experimental methods (e.g., pulse sequences) or conditions (e.g., MAS frequency, magnitude of anisotropic interaction, radio-frequency field amplitudes) is not fully understood. To investigate these questions, we performed numerical simulations of dynamic systems based on the stochastic Liouville equation using several experiments for recoupling the dipolar coupling, chemical-shift anisotropy or quadrupolar coupling. As described in the literature, the transition between slow motion, where parameters characterizing the anisotropic interaction are not averaged, and fast motion, where the tensors are averaged leading to a scaled anisotropic quantity, occurs over a window of motional rate constants that depends mainly on the strength of the interaction. This transition region can span 2 orders of magnitude in exchange-rate constants (typically in the microsecond range) but depends only marginally on the employed recoupling scheme or sample spinning frequency. The transition region often coincides with a fast relaxation of coherences, making precise quantitative measurements difficult. Residual couplings in off-magic-angle experiments, however, average over longer timescales of motion. While in principle one may gain information on the timescales of motion from the transition area, extracting such information is hampered by low signal-to-noise ratio in experimental spectra due to fast relaxation that occurs in the same region.
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Sluysmans, Damien, Floriane Devaux, Carson J. Bruns, J. Fraser Stoddart, and Anne-Sophie Duwez. "Dynamic force spectroscopy of synthetic oligorotaxane foldamers." Proceedings of the National Academy of Sciences 115, no. 38 (December 26, 2017): 9362–66. http://dx.doi.org/10.1073/pnas.1712790115.
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Wholly synthetic molecules involving both mechanical bonds and a folded secondary structure are one of the most promising architectures for the design of functional molecular machines with unprecedented properties. Here, we report dynamic single-molecule force spectroscopy experiments that explore the energetic details of donor–acceptor oligorotaxane foldamers, a class of molecular switches. The mechanical breaking of the donor–acceptor interactions responsible for the folded structure shows a high constant rupture force over a broad range of loading rates, covering three orders of magnitude. In comparison with dynamic force spectroscopy performed during the past 20 y on various (bio)molecules, the near-equilibrium regime of oligorotaxanes persists at much higher loading rates, at which biomolecules have reached their kinetic regime, illustrating the very fast dynamics and remarkable rebinding capabilities of the intramolecular donor–acceptor interactions. We focused on one single interaction at a time and probed the stochastic rupture and rebinding paths. Using the Crooks fluctuation theorem, we measured the mechanical work produced during the breaking and rebinding to determine a free-energy difference, ΔG, of 6 kcal·mol−1 between the two local conformations around a single bond.
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Zhu, Junyao, Mingming Chen, Junfeng Lu, Kun Zhao, Enze Cui, Zhiheng Zhang, and Hong Wan. "A Fast and Efficient Ensemble Transfer Entropy and Applications in Neural Signals." Entropy 24, no. 8 (August 13, 2022): 1118. http://dx.doi.org/10.3390/e24081118.
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The ensemble transfer entropy (TEensemble) refers to the transfer entropy estimated from an ensemble of realizations. Due to its time-resolved analysis, it is adapted to analyze the dynamic interaction between brain regions. However, in the traditional TEensemble, multiple sets of surrogate data should be used to construct the null hypothesis distribution, which dramatically increases the computational complexity. To reduce the computational cost, a fast, efficient TEensemble with a simple statistical test method is proposed here, in which just one set of surrogate data is involved. To validate the improved efficiency, the simulated neural signals are used to compare the characteristics of the novel TEensemble with those of the traditional TEensemble. The results show that the time consumption is reduced by two or three magnitudes in the novel TEensemble. Importantly, the proposed TEensemble could accurately track the dynamic interaction process and detect the strength and the direction of interaction robustly even in the presence of moderate noises. The novel TEensemble reaches its steady state with the increased samples, which is slower than the traditional method. Furthermore, the effectiveness of the novel TEensemble was verified in the actual neural signals. Accordingly, the TEensemble proposed in this work may provide a suitable way to investigate the dynamic interactions between brain regions.
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Sun, Wenxu, Bin Xue, Qiyang Fan, Runhan Tao, Chunxi Wang, Xin Wang, Yiran Li, et al. "Molecular engineering of metal coordination interactions for strong, tough, and fast-recovery hydrogels." Science Advances 6, no. 16 (April 2020): eaaz9531. http://dx.doi.org/10.1126/sciadv.aaz9531.
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Many load-bearing tissues, such as muscles and cartilages, show high elasticity, toughness, and fast recovery. However, combining these mechanical properties in the same synthetic biomaterials is fundamentally challenging. Here, we show that strong, tough, and fast-recovery hydrogels can be engineered using cross-linkers involving cooperative dynamic interactions. We designed a histidine-rich decapeptide containing two tandem zinc binding motifs. Because of allosteric structural change-induced cooperative binding, this decapeptide had a higher thermodynamic stability, stronger binding strength, and faster binding rate than single binding motifs or isolated ligands. The engineered hybrid network hydrogels containing the peptide-zinc complex exhibit a break stress of ~3.0 MPa, toughness of ~4.0 MJ m−3, and fast recovery in seconds. We expect that they can function effectively as scaffolds for load-bearing tissue engineering and as building blocks for soft robotics. Our results provide a general route to tune the mechanical and dynamic properties of hydrogels at the molecular level.
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Horswill, Ian. "Lightweight Procedural Animation with Believable Physical Interactions." Proceedings of the AAAI Conference on Artificial Intelligence and Interactive Digital Entertainment 4, no. 1 (September 27, 2021): 48–53. http://dx.doi.org/10.1609/aiide.v4i1.18671.
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I describe a procedural animation system that uses techniques from behavior-based robot control, combined with a minimalist physical simulation, to produce believable character motions in a dynamic world. Although less realistic than motion capture or full biomechanical simulation, the system produces compelling, responsive character behavior. It is also fast, supports believable physical interactions between characters such as hugging, and makes it easy to author new behaviors.
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Han, Fang, Dong Wang Zhong, and Ji Yun Mo. "Discriminant Condition of Influencing Dynamic Response for Structure-Equipment System." Applied Mechanics and Materials 90-93 (September 2011): 1477–81. http://dx.doi.org/10.4028/www.scientific.net/amm.90-93.1477.
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In structure-equipment system, there are complex dynamic interactions between structures and equipments. A fast discriminant condition whether the interaction will increase or decrease dynamic response of the structure is achieved in this paper. When the load frequency lies between the basic frequencies of the combined system, it decreases the absolute response of the structure and vice versa. In engineering project, the seismic load can be expanded based on ground characteristic frequency by Fourier transform, so our conclusion can be extended to seismic design for combined systems. Finite element method simulation for a chemical workshop further verifies the discriminant condition.
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Leminen, Seppo. "Development of gaps in buyer‐seller relationships." Management Decision 39, no. 6 (August 1, 2001): 470–74. http://dx.doi.org/10.1108/eum0000000005564.
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The purpose of this study is to increase understanding of the dynamics of gaps in buyer‐seller relationships. Increasingly complex, fast changing, and dynamic business environments provide a rich research environment for analysing dynamics of gaps in business relationships. Traditionally gaps have been examined from the static and single party perspective. However, dyadic buyer‐seller relationships can be revealed, described, and analysed in new ways by viewing intraorganisational and interorganisational gaps longitudinally as chains of interactions in relationships and from the perspectives of several parties. The dynamic gaps of the relationships are described and analysed longitudinally from the perspective of gaps for the first time.
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Kazda, Jonas, and Nicolaos Cutululis. "Fast Control-Oriented Dynamic Linear Model of Wind Farm Flow and Operation." Energies 11, no. 12 (November 30, 2018): 3346. http://dx.doi.org/10.3390/en11123346.
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The aerodynamic interaction between wind turbines grouped in wind farms results in wake-induced power loss and fatigue loads of wind turbines. To mitigate these, wind farm control should be able to account for those interactions, typically using model-based approaches. Such model-based control approaches benefit from computationally fast, linear models and therefore, in this work, we introduce the Dynamic Flow Predictor. It is a fast, control-oriented, dynamic, linear model of wind farm flow and operation that provides predictions of wind speed and turbine power. The model estimates wind turbine aerodynamic interaction using a linearized engineering wake model in combination with a delay process. The Dynamic Flow Predictor was tested on a two-turbine array to illustrate its main characteristics and on a large-scale wind farm, comparable to modern offshore wind farms, to illustrate its scalability and accuracy in a more realistic scale. The simulations were performed in SimWindFarm with wind turbines represented using the NREL 5 MW model. The results showed the suitability, accuracy, and computational speed of the modeling approach. In the study on the large-scale wind farm, rotor effective wind speed was estimated with a root-mean-square error ranging between 0.8% and 4.1%. In the same study, the computation time per iteration of the model was, on average, 2.1 × 10 − 5 s. It is therefore concluded that the presented modeling approach is well suited for use in wind farm control.
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Bidari, Subekshya, Orit Peleg, and Zachary P. Kilpatrick. "Social inhibition maintains adaptivity and consensus of honeybees foraging in dynamic environments." Royal Society Open Science 6, no. 12 (December 2019): 191681. http://dx.doi.org/10.1098/rsos.191681.
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To effectively forage in natural environments, organisms must adapt to changes in the quality and yield of food sources across multiple timescales. Individuals foraging in groups act based on both their private observations and the opinions of their neighbours. How do these information sources interact in changing environments? We address this problem in the context of honeybee colonies whose inhibitory social interactions promote adaptivity and consensus needed for effective foraging. Individual and social interactions within a mathematical model of collective decisions shape the nutrition yield of a group foraging from feeders with temporally switching quality. Social interactions improve foraging from a single feeder if temporal switching is fast or feeder quality is low. When the colony chooses from multiple feeders, the most beneficial form of social interaction is direct switching, whereby bees flip the opinion of nest-mates foraging at lower-yielding feeders. Model linearization shows that effective social interactions increase the fraction of the colony at the correct feeder (consensus) and the rate at which bees reach that feeder (adaptivity). Our mathematical framework allows us to compare a suite of social inhibition mechanisms, suggesting experimental protocols for revealing effective colony foraging strategies in dynamic environments.
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Liu, Hanyun, Zhiwu Yu, and Wei Guo. "A Fast Modeling Technique for the Vertical Train-Track-Bridge Interactions." Shock and Vibration 2019 (April 28, 2019): 1–14. http://dx.doi.org/10.1155/2019/5392930.
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This paper proposed a fast modeling technique (FMT) for the vertical dynamic analysis of the coupled train-track-bridge (TTB) systems, which combines the train subsystems and track-bridge subsystems by the client-server technique to complete the entire TTB analysis on simplex OpenSees simulation platform. Thus, the FMT could dramatically reduce the time consumed of programming and modeling and significantly reduce the amount of data transmission between subsystems for TTB interaction. Moreover, FMT could take full advantage of OpenSees in nonlinear and seismic analysis. So FMT is a practical and convenient approach to analyze the TTB coupling vibration, and especially it is suitable for the junior researchers of TTB interaction. FMT could improve the modeling efficiency to save time.
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Leistritz, L., W. Hesse, T. Wüstenberg, C. Fitzek, J. R. Reichenbach, and H. Witte. "Time-variant Analysis of Fast-fMRI and Dynamic Contrast Agent MRI Sequences as Examples of 4-dimensional Image Analysis." Methods of Information in Medicine 45, no. 06 (2006): 643–50. http://dx.doi.org/10.1055/s-0038-1634129.
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Summary Objectives: Image sequences with time-varying information content need appropriate analysis strategies. The exploration of directed information transfer (interactions) between neuronal assemblies is one of the most important aims of current functional MRI (fMRI) analysis. Additionally, we examined perfusion maps in dynamic contrast agent MRI sequences of stroke patients. In this investigation, the focus centers on distinguishing between brain areas with normal and reduced perfusion on the basis of the dynamics of contrast agent inflow and washout. Methods: Fast fMRI sequences were analyzed with time-variant Granger causality (tvGC). The tvGC is based on a time-variant autoregressive model and is used for the quantification of the directed information transfer between activated brain areas. Generalized Dynamic Neural Networks (GDNN) with time-variant weights were applied on dynamic contrast agent MRI sequences as a nonlinear operator in order to enhance differences in the signal courses of pixels of normal and injured tissues. Results: A simple motor task (self-paced finger tapping) is used in an fMRI design to investigate directed interactions between defined brain areas. A significant information transfer can be determined for the direction primary motor cortex to supplementary motor area during a short time period of about five seconds after stimulus. The analysis of dynamic contrast agent MRI sequences demonstrates that the trained GDNN enables a reliable tissue classification. Three classes are of interest: normal tissue, tissue at risk for death, and dead tissue. Conclusions: The time-variant multivariate analysis of directed information transfer derived from fMRI sequences and the computation of perfusion maps by GDNN demonstrate that dynamic analysis methods are essential tools for 4D image analysis.
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Williams, R. E., and S. M. Horvath. "Recovery from dynamic exercise." American Journal of Physiology-Heart and Circulatory Physiology 268, no. 6 (June 1, 1995): H2311—H2320. http://dx.doi.org/10.1152/ajpheart.1995.268.6.h2311.
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Minimal information is available on the basic interactions within the metabolic and cardiovascular systems during recovery from exercise. Nine men participated in three experiments: one control and two cost-equivalent (52 liters O2) exercise tests of 30 (EX30) and 45 (EX45) min. Exercise intensities were adjusted accordingly. During recovery, all parameters reestablished baseline levels within 10 min, except for heart rate (30 min). Correlations for each parameter for EX30 and EX45 were obtained by evaluating each subject's exercise cost and recovery "payback." A split, two-factor analysis of variance was run separately on the "fast" (minutes 1-7) and "slow" (minutes 10-60) phases of recovery to determine if the time course of recovery was related to exercise intensity. It was concluded that for a work cost of approximately 300 kcal, 1) the slow phase of recovery was unaffected by the exercise intensity, 2) the fast phase of cardiovascular recovery was unaffected by exercise intensity while minute ventilation and O2 and CO2 uptake were affected, and 3) cardiac output and the ventilatory equivalents for O2 and CO2 correlated well between work cost and recovery payback.
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Mao, Haiyan, Qun Zhang, Ling Lin, Xuemei He, and Lili Wang. "A Self-Healable and Recyclable Zwitterionic Polyurethane Based on Dynamic Ionic Interactions." Polymers 15, no. 5 (March 2, 2023): 1270. http://dx.doi.org/10.3390/polym15051270.
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Polyurethanes with self-healing and reprocessing capabilities are promising in eco-friendly applications. Here, a self-healable and recyclable zwitterionic polyurethane (ZPU) was developed by introducing ionic bonds between protonated ammonium groups and sulfonic acid moieties. The structure of the synthesized ZPU was characterized by FTIR and XPS. The thermal, mechanical, self-healing and recyclable properties of ZPU were also investigated in detail. Compared with cationic polyurethane (CPU), ZPU shows similar thermal stability. The physical cross-linking network formed between zwitterion groups can dissipate strain energy as a weak dynamic bond, endowing ZPU with outstanding mechanical and elastic recovery properties, including the high tensile strength of 7.38 MPa, high elongation at a break of 980%, and fast elastic recovery ability. Additionally, ZPU exhibits a healing efficiency of over 93% at 50 °C for 1.5 h as a result of the dynamic reconstruction of reversible ionic bonds. Furthermore, ZPU can be well reprocessed by solution casting and hot-pressing with a recovery efficiency above 88%. The excellent mechanical properties, fast repairing capability, and good recyclability not only enable polyurethane with a promising application in protective coatings for textiles and paints but also make it a superior candidate as stretchable substrates for wearable electronic devices and strain sensors.
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Clarke, David T., and Marisa L. Martin-Fernandez. "A Brief History of Single-Particle Tracking of the Epidermal Growth Factor Receptor." Methods and Protocols 2, no. 1 (January 30, 2019): 12. http://dx.doi.org/10.3390/mps2010012.
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Single-particle tracking (SPT) has been used and developed over the last 25 years as a method to investigate molecular dynamics, structure, interactions, and function in the cellular context. SPT is able to show how fast and how far individual molecules move, identify different dynamic populations, measure the duration and strength of intermolecular interactions, and map out structures on the nanoscale in cells. In combination with other techniques such as macromolecular crystallography and molecular dynamics simulation, it allows us to build models of complex structures, and develop and test hypotheses of how these complexes perform their biological roles in health as well as in disease states. Here, we use the example of the epidermal growth factor receptor (EGFR), which has been studied extensively by SPT, demonstrating how the method has been used to increase our understanding of the receptor’s organization and function, including its interaction with the plasma membrane, its activation, clustering, and oligomerization, and the role of other receptors and endocytosis. The examples shown demonstrate how SPT might be employed in the investigation of other biomolecules and systems.
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Pan, Like, Yan Xu, Zhendong Liu, Chonhui Xiao, and Jilin Lei. "A Fast Simulation Model of Pantograph–Stitched-Catenary Interaction in Long-Distance Travel." Applied Sciences 14, no. 22 (November 6, 2024): 10160. http://dx.doi.org/10.3390/app142210160.
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The increasing operation speed of high-speed trains allows the pantograph to continuously interact with the catenary over a long distance in a short time, and many new methods have been developed to efficiently calculate its dynamics. However, the existing methods only consider simple catenary systems, which limits their application in high-speed railway systems. In this work, a reduced pantograph–stitched-catenary interaction model is developed to simulate pantograph–stitched-catenary interactions during long-distance travel. Based on the existing reduced catenary model, the stitched catenary system is first considered, where the stitched wire is simplified into a part of the messenger wire supported by two spring-damping elements. The present model is validated by test results and the EN 50318:2018 standard, and it is subsequently used to study the dynamic performance of the pantograph–stitched-catenary system at an overdesigned speed in Sweden. The results show that the proposed model can be seven times faster than the traditional modal superposition method with the same accuracy in a stitched catenary system, and the existing catenary system cannot be operated at an overdesigned speed without increasing the contact wire tension. The present model gives an efficient solution to pantograph–stitched-catenary interaction problems.
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Baker, I., F. Liu, K. Jia, X. Hu, D. Cullen, and M. Dudley. "Dynamic observations of dislocation/grain-boundary interactions in ice." Annals of Glaciology 31 (2000): 236–40. http://dx.doi.org/10.3189/172756400781820525.
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AbstractDislocation/grain-boundary (GB) interactions have been studied in situ in polycrystalline ice using synchrotron X-ray topography in the temperature range 0° to –15°C GBs were observed to act both as sources of lattice dislocations and as strong obstacles to dislocation motion. Dislocations were observed to form pile-ups at GBs upon loading. Generally the basal slip system with the highest Schmid factor was found to be the most active, and dislocations were emitted from GB facets as semi-hexagonal loops in order to relieve the stress build-up from GB sliding. When the relative orientation of two adjacent grains and the orientation of the GB between them with respect to the loading direction discouraged GB sliding, thus suppressing dislocation nucleation at the GB, dislocations originating in one grain piled up at the GB and led to slip transmission through the GB The latter geometrical arrangement is rarely encountered, suggesting that slip transmission through grain boundaries in ice is a rare event. When basal slip was suppressed, i.e. when the loading direction lay in the basal plane, slip occurred by the glide of a fast edge segment on non-basal planes.
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Li, Xin, Wei Huang, Elizabeth A. Morris, Luminita A. Tudorica, Venkatraman E. Seshan, William D. Rooney, Ian Tagge, Ya Wang, Jingang Xu, and Charles S. Springer. "Dynamic NMR effects in breast cancer dynamic-contrast-enhanced MRI." Proceedings of the National Academy of Sciences 105, no. 46 (November 13, 2008): 17937–42. http://dx.doi.org/10.1073/pnas.0804224105.
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The passage of a vascular-injected paramagnetic contrast reagent (CR) bolus through a region-of-interest affects tissue 1H2O relaxation and thus MR image intensity. For longitudinal relaxation [R1 ≡ (T1)−1], the CR must have transient molecular interactions with water. Because the CR and water molecules are never uniformly distributed in the histological-scale tissue compartments, the kinetics of equilibrium water compartmental interchange are competitive. In particular, the condition of the equilibrium trans cytolemmal water exchange NMR system sorties through different domains as the interstitial CR concentration, [CRo], waxes and wanes. Before CR, the system is in the fast-exchange-limit (FXL). Very soon after CRo arrival, it enters the fast-exchange-regime (FXR). Near maximal [CRo], the system could enter even the slow-exchange-regime (SXR). These conditions are defined herein, and a comprehensive description of how they affect quantitative pharmacokinetic analyses is presented. Data are analyzed from a population of 22 patients initially screened suspicious for breast cancer. After participating in our study, the subjects underwent biopsy/pathology procedures and only 7 (32%) were found to have malignancies. The transient departure from FXL to FXR (and apparently not SXR) is significant in only the malignant tumors, presumably because of angiogenic capillary leakiness. Thus, if accepted, this analysis would have prevented the 68% of the biopsies that proved benign.
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Minaev, Andrey, and Anton Minaev. "Vibratory interactions in sports equipment on laboratory test-beds." BIO Web of Conferences 138 (2024): 04008. http://dx.doi.org/10.1051/bioconf/202413804008.
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The issue of how athletes interact with sports equipment and the shocks and vibrations that occur in the system is not well understood. The recording and analysis of the dynamic processes occurring in the support interactions is an effective tool for improving performance and success in any sport. The challenge lies in the fact that to record vibrations and vibrations in the process of contact (in most cases, impact) between the athlete and the equipment, a set of highly accurate and expensive recording equipment for fast processes is required. This further necessitates careful and detailed analysis. To achieve the desired results, it is essential to utilize laboratory test beds for comprehensive recording, analysis, and detailed examination of dynamic characteristics, vibration effects on sports equipment, and their impact on the athlete's body. This paper demonstrates the effectiveness of using a vibration test-bed in the formed sequential biomechanical system "ball-strings-rim-arm-handle-arm," which allows for the modeling of different variants of tests. A miniature impactor can also be used to record and analyze the propagation characteristics of the impact process in the presented biomechanical system. This can be done using the small laboratory impact test-bed. As technology advances, we will find optimal solutions and achieve better results.
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Pasquali, S., E. Frezza, and F. L. Barroso da Silva. "Coarse-grained dynamic RNA titration simulations." Interface Focus 9, no. 3 (April 19, 2019): 20180066. http://dx.doi.org/10.1098/rsfs.2018.0066.
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Electrostatic interactions play a pivotal role in many biomolecular processes. The molecular organization and function in biological systems are largely determined by these interactions. Owing to the highly negative charge of RNA, the effect is expected to be more pronounced in this system. Moreover, RNA base pairing is dependent on the charge of the base, giving rise to alternative secondary and tertiary structures. The equilibrium between uncharged and charged bases is regulated by the solution pH, which is therefore a key environmental condition influencing the molecule’s structure and behaviour. By means of constant-pH Monte Carlo simulations based on a fast proton titration scheme, coupled with the coarse-grained model HiRE-RNA, molecular dynamic simulations of RNA molecules at constant pH enable us to explore the RNA conformational plasticity at different pH values as well as to compute electrostatic properties as local p K a values for each nucleotide.
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Kim, Dong-Il, Yongsoo Park, Deok-Jin Jang, and Byung-Chang Suh. "Dynamic phospholipid interaction of β2e subunit regulates the gating of voltage-gated Ca2+ channels." Journal of General Physiology 145, no. 6 (May 11, 2015): 529–41. http://dx.doi.org/10.1085/jgp.201411349.
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High voltage-activated Ca2+ (CaV) channels are protein complexes containing pore-forming α1 and auxiliary β and α2δ subunits. The subcellular localization and membrane interactions of the β subunits play a crucial role in regulating CaV channel inactivation and its lipid sensitivity. Here, we investigated the effects of membrane phosphoinositide (PI) turnover on CaV2.2 channel function. The β2 isoform β2e associates with the membrane through electrostatic and hydrophobic interactions. Using chimeric β subunits and liposome-binding assays, we determined that interaction between the N-terminal 23 amino acids of β2e and anionic phospholipids was sufficient for β2e membrane targeting. Binding of the β2e subunit N terminus to liposomes was significantly increased by inclusion of 1% phosphatidylinositol 4,5-bisphosphate (PIP2) in the liposomes, suggesting that, in addition to phosphatidylserine, PIs are responsible for β2e targeting to the plasma membrane. Membrane binding of the β2e subunit slowed CaV2.2 current inactivation. When membrane phosphatidylinositol 4-phosphate and PIP2 were depleted by rapamycin-induced translocation of pseudojanin to the membrane, however, channel opening was decreased and fast inactivation of CaV2.2(β2e) currents was enhanced. Activation of the M1 muscarinic receptor elicited transient and reversible translocation of β2e subunits from membrane to cytosol, but not that of β2a or β3, resulting in fast inactivation of CaV2.2 channels with β2e. These results suggest that membrane targeting of the β2e subunit, which is mediated by nonspecific electrostatic insertion, is dynamically regulated by receptor stimulation, and that the reversible association of β2e with membrane PIs results in functional changes in CaV channel gating. The phospholipid–protein interaction observed here provides structural insight into mechanisms of membrane–protein association and the role of phospholipids in ion channel regulation.
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Duris, Rastislav. "A Determination of Material Properties of Flexible Structures Using EMA and FEM Analysis." Applied Mechanics and Materials 693 (December 2014): 293–98. http://dx.doi.org/10.4028/www.scientific.net/amm.693.293.
Full textAbstract:
Dynamic behavior of mechanical structures results from complex interactions between applied forces and the stiffness properties of the structure. Currently, many problems of structural dynamic analysis are solved using Finite Element Method (FEM). However, in recent years, the implementation of the Fast Fourier Transform (FFT) in low cost computer-based signal analyzers has provided a powerful tool for acquisition and analysis of vibration data. This article discusses combination of two approaches to structural dynamics testing; the experimental part which is referred to as Experimental Modal Analysis (EMA), respectively the analytical part, which is realized by Finite Element Analysis (FEA). Main goal of the paper is calculation of material properties from experimentally determined modal frequencies.
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Liu, Yongguang, Wei Chen, and Zhu Huang. "Reinforcement Learning-Based Multiple Constraint Electric Vehicle Charging Service Scheduling." Mathematical Problems in Engineering 2021 (November 15, 2021): 1–12. http://dx.doi.org/10.1155/2021/1401802.
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The popularization of electric vehicles faces problems such as difficulty in charging, difficulty in selecting fast charging locations, and comprehensive consideration of multiple factors and vehicle interactions. With the increasingly mature application of navigation technology in vehicle-road coordination and other aspects, the proposal of an optimal dynamic charging method for electric fleets based on adaptive learning makes it possible for edge computing to process electric fleets to effectively execute the optimal route charging plan. We propose a method of electric vehicle charging service scheduling based on reinforcement learning. First, an intelligent transportation system is proposed, and on this basis a framework for the interaction between fast charging stations and electric vehicles is established. Subsequently, a dynamic travel time model for traffic sections was established. Based on the habits of electric vehicle owners, an electric vehicle charging navigation model and a reinforcement learning reward model were proposed. Finally, an electric vehicle charging navigation scheduling method is proposed to optimize the service resources of the fast charging stations in the area. The simulation results show that the method balances the charging load between stations, can effectively improve the charging efficiency of electric vehicles, and increases user satisfaction.
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Suzuki, Daisuke, Shigeru Horiuchi, Jin Hwan Choi, and Han Sik Ryu. "Dynamic Analysis of Contacting Spur Gear Pair for Fast System Simulation." Solid State Phenomena 110 (March 2006): 151–62. http://dx.doi.org/10.4028/www.scientific.net/ssp.110.151.
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The prime source of vibration and noise in a gear system is originated from transmission error between the meshing gears. In this paper, the dynamic modeling method and response of a spur gear pair for the efficient system simulation are investigated by using a detailed contact analysis at each time step. Input values such as time-varying mesh stiffness and static transmission error excitation are not required in this investigation because mesh forces are obtained by contact analysis directly. The efficient contact search kinematics and algorithms in the context of the compliant contact model are developed to detect the interactions between teeth surfaces. In this investigation the compliant force model based on the Herzian law is employed using Coulomb friction force model, and dynamic transmission error (DTE) and mesh frequency values of contacting gear system are also illustrated.
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Kharchenko, Vladlena, Michal Nowakowski, Mariusz Jaremko, Andrzej Ejchart, and Łukasz Jaremko. "Dynamic 15N{1H} NOE measurements: a tool for studying protein dynamics." Journal of Biomolecular NMR 74, no. 12 (September 12, 2020): 707–16. http://dx.doi.org/10.1007/s10858-020-00346-6.
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AbstractIntramolecular motions in proteins are one of the important factors that determine their biological activity and interactions with molecules of biological importance. Magnetic relaxation of 15N amide nuclei allows one to monitor motions of protein backbone over a wide range of time scales. 15N{1H} nuclear Overhauser effect is essential for the identification of fast backbone motions in proteins. Therefore, exact measurements of NOE values and their accuracies are critical for determining the picosecond time scale of protein backbone. Measurement of dynamic NOE allows for the determination of NOE values and their probable errors defined by any sound criterion of nonlinear regression methods. The dynamic NOE measurements can be readily applied for non-deuterated or deuterated proteins in both HSQC and TROSY-type experiments. Comparison of the dynamic NOE method with commonly implied steady-state NOE is presented in measurements performed at three magnetic field strengths. It is also shown that improperly set NOE measurement cannot be restored with correction factors reported in the literature.
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Das, Anup, and Vinod Menon. "Spatiotemporal Integrity and Spontaneous Nonlinear Dynamic Properties of the Salience Network Revealed by Human Intracranial Electrophysiology: A Multicohort Replication." Cerebral Cortex 30, no. 10 (May 19, 2020): 5309–21. http://dx.doi.org/10.1093/cercor/bhaa111.
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Abstract The salience network (SN) plays a critical role in cognitive control and adaptive human behaviors, but its electrophysiological foundations and millisecond timescale dynamic temporal properties are poorly understood. Here, we use invasive intracranial EEG (iEEG) from multiple cohorts to investigate the neurophysiological underpinnings of the SN and identify dynamic temporal properties that distinguish it from the default mode network (DMN) and dorsolateral frontal–parietal network (FPN), two other large-scale brain networks that play important roles in human cognition. iEEG analysis of network interactions revealed that the anterior insula and anterior cingulate cortex, which together anchor the SN, had stronger intranetwork interactions with each other than cross-network interactions with the DMN and FPN. Analysis of directionality of information flow between the SN, DMN, and FPN revealed causal outflow hubs in the SN consistent with its role in fast temporal switching of network interactions. Analysis of regional iEEG temporal fluctuations revealed faster temporal dynamics and higher entropy of neural activity within the SN, compared to the DMN and FPN. Critically, these results were replicated across multiple cohorts. Our findings provide new insights into the neurophysiological basis of the SN, and more broadly, foundational mechanisms underlying the large-scale functional organization of the human brain.
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Acanfora, Maria, and Antonio Cirillo. "On the development of a fast modeling of floodwater effects on ship motions in waves." Proceedings of the Institution of Mechanical Engineers, Part M: Journal of Engineering for the Maritime Environment 231, no. 4 (February 14, 2017): 877–87. http://dx.doi.org/10.1177/1475090216687438.
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The motions of a flooded ship in waves are difficult to evaluate. They are affected by complex phenomena involving ship and floodwater dynamic interactions. Several numerical methods have been proposed to estimate the dynamic behavior of a damaged ship in waves. In this article, a fast simulation tool is developed to tackle the problem, aiming at a simplified method with an acceptable accuracy of the results. A novel approach in simulating floodwater effects on ship motions is presented. The method allows modeling the floodwater motions (seen as lumped mass) out of phase from ship motions. This technique is based on the basic fluid mechanics knowledge for a liquid in a uniformly accelerated tank. The study intends to analyze the behavior of a flooded ship in regular beam waves, for compartment fillings that involve shallow and intermediate fluid depths. The nonlinear model for the roll damping moment of a ship is implemented. An attempt to model viscous effects in the floodwater dynamics is proposed and applied. Two sets of applications are carried out on two different hull models. The comparisons of the intact and of the flooded ship responses in waves are conducted and discussed.
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Hunt, Neil T. "Minding the dynamic gap: measuring ultrafast processes in biomolecular systems." Biochemist 41, no. 2 (April 1, 2019): 30–35. http://dx.doi.org/10.1042/bio04102030.
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Biological processes in vivo involve interactions between large, complex molecules under conditions that are best-approximated by a viscous, multicomponent solution at temperatures often somewhat above room temperature. This means that the molecules involved are dynamic --- their structure changes --- on many timescales in ways that range from very small, localized fluctuations to fundamental changes in their overall appearance. What roles do these dynamics play in the structure–function relationship? Do very fast, local motions have any impact on well-characterized, slower structure changes? How do we go about measuring the very fastest biomolecular fluctuations to find out? Here we discuss ultrafast multidimensional (2D-IR) spectroscopy and look at the complementary information that it provides as part of a raft of biophysical experiments.
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Woringer, Maxime, and Xavier Darzacq. "Protein motion in the nucleus: from anomalous diffusion to weak interactions." Biochemical Society Transactions 46, no. 4 (July 31, 2018): 945–56. http://dx.doi.org/10.1042/bst20170310.
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Understanding how transcription factors (TFs) regulate mammalian gene expression in space and time is a central topic in biology. To activate a gene, a TF has first to diffuse in the available space of the nucleus until it reaches a target DNA sequence or protein (target site). This eventually results in the recruitment of the whole transcriptional machinery. All these processes take place in the mammalian nucleoplasm, a highly organized and dynamic environment, in which some complexes transiently assemble and break apart, whereas others appear more stable. This diversity of dynamic behaviors arises from the number of biomolecules that make up the nucleoplasm and their pairwise interactions. Indeed, interactions energies that span several orders of magnitude, from covalent bounds to transient and dynamic interactions, can shape nuclear landscapes. Thus, the nuclear environment determines how frequently and how fast a TF contacts its target site, and it indirectly regulates gene expression. How exactly transient interactions are involved in the regulation of TF diffusion is unclear, but are reflected by live cell imaging techniques, including single-particle tracking (SPT). Overall, the macroscopic result of these microscopic interactions is almost always anomalous diffusion, a phenomenon widely studied and modeled. Here, we review the connections between the anomalous diffusion of a TF observed by SPT and the microscopic organization of the nucleus, including recently described topologically associated domains and dynamic phase-separated compartments. We propose that anomalous diffusion found in SPT data result from weak and transient interactions with dynamic nuclear substructures, and that SPT data analysis would benefit from a better description of such structures.
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Dell'Orco, Daniele, and Karl-Wilhelm Koch. "A dynamic scaffolding mechanism for rhodopsin and transducin interaction in vertebrate vision." Biochemical Journal 440, no. 2 (November 14, 2011): 263–71. http://dx.doi.org/10.1042/bj20110871.
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The early steps in vertebrate vision require fast interactions between Rh (rhodopsin) and Gt (transducin), which are classically described by a collisional coupling mechanism driven by the free diffusion of monomeric proteins on the disc membranes of rod and cone cells. Recent findings, however, point to a very low mobility for Rh and support a substantially different supramolecular organization. Moreover, Rh–Gt interactions seem to possibly occur even prior to light stimuli, which is also difficult to reconcile with the classical scenario. We investigated the kinetics of interaction between native Rh and Gt in different conditions by surface plasmon resonance and analysed the results in the general physiological context by employing a holistic systems modelling approach. The results from the present study point to a mechanism that is intermediate between pure collisional coupling and physical scaffolding. Such a ‘dynamic scaffolding’, in which prevalently dimeric Rh and Gt interact in the dark by forming transient complexes (~25% of Gt is precoupled to Rh), does not slow down the phototransduction cascade, but is compatible with the observed photoresponses on a broad scale of light stimuli. We conclude that Rh molecules and Rh–Gt complexes can both absorb photons and trigger the visual cascade.
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Deng, Shujie, Gavin Wheeler, Nicolas Toussaint, Lindsay Munroe, Suryava Bhattacharya, Gina Sajith, Ei Lin, et al. "A Virtual Reality System for Improved Image-Based Planning of Complex Cardiac Procedures." Journal of Imaging 7, no. 8 (August 19, 2021): 151. http://dx.doi.org/10.3390/jimaging7080151.
Full textAbstract:
The intricate nature of congenital heart disease requires understanding of the complex, patient-specific three-dimensional dynamic anatomy of the heart, from imaging data such as three-dimensional echocardiography for successful outcomes from surgical and interventional procedures. Conventional clinical systems use flat screens, and therefore, display remains two-dimensional, which undermines the full understanding of the three-dimensional dynamic data. Additionally, the control of three-dimensional visualisation with two-dimensional tools is often difficult, so used only by imaging specialists. In this paper, we describe a virtual reality system for immersive surgery planning using dynamic three-dimensional echocardiography, which enables fast prototyping for visualisation such as volume rendering, multiplanar reformatting, flow visualisation and advanced interaction such as three-dimensional cropping, windowing, measurement, haptic feedback, automatic image orientation and multiuser interactions. The available features were evaluated by imaging and nonimaging clinicians, showing that the virtual reality system can help improve the understanding and communication of three-dimensional echocardiography imaging and potentially benefit congenital heart disease treatment.
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Shahravi, Morteza, and Milad Azimi. "A Hybrid Scheme of Synthesized Sliding Mode/Strain Rate Feedback Control Design for Flexible Spacecraft Attitude Maneuver Using Time Scale Decomposition." International Journal of Structural Stability and Dynamics 16, no. 02 (February 25, 2016): 1450101. http://dx.doi.org/10.1142/s0219455414501016.
Full textAbstract:
Presented herein is a new control approach for large angle attitude maneuver of flexible spacecraft. The singular perturbation theory (SPT) provides a useful tool for two time rate scale separation (mapping) of rigid and flexible body dynamics. The resulting slow and fast subsystems, enabling the use of two control approach for attitude (Modified Sliding Mode) and vibration Strain Rate Feedback (SRF) control of flexible spacecraft, respectively. An attractive feature of the present control approach is that the global stability of the entire system has been guaranteed while the controllers accomplished their tasks in coupled rigid/flexible dynamic domain without parasitic parameter interactions. Numerical simulations show the effectiveness of the present approach.
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Neverova, G. P., and O. L. Zhdanova. "Comparative Dynamics Analysis of Simple Mathematical Models of the Plankton Communities Considering Various Types of Response Function." Mathematical Biology and Bioinformatics 17, no. 2 (December 19, 2022): 465–80. http://dx.doi.org/10.17537/2022.17.465.
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The paper proposes a two-component discrete-time model of the plankton community, taking into account features of the development and interaction of phytoplankton and zooplankton. To describe the interaction between these species and to compare the system dynamics, we use the following set of response functions: type II and III Holling function and the Arditi–Ginzburg response function, each of which describes trophic interactions between phytoplankton and zooplankton. An analytical and numerical study of the model proposed is made. The analysis shows that the variation of trophic functions does not change the dynamic behavior of the model fundamentally. The stability loss of nontrivial fixed point corresponding to the coexistence of phytoplankton and zooplankton can occur through a cascade of period-doubling bifurcations and according to the Neimark–Saker scenario, which allows us to observe the appearance of long-period oscillations representing the alternation of peaks and reduction in the number of species as a result of the predator-prey interaction. As well, the model has multistability areas, where a variation in initial conditions with the unchanged values of all model parameters can result in a shift of the current dynamic mode. Each of the models is shown to demonstrate conditional coexistence when a variation of the current community structure can lead to the extinction of the entire community or its part. Considering the characteristics of the species composition, the model with the type II Holling function seems a more suitable for describing the dynamics of the plankton community. Such a system is consistent with the idea that phytoplankton is a fast variable and predator dynamics is slow; thus, long-period fluctuations occur at high phytoplankton growth rates and low zooplankton ones. The model with the Arditi–Ginzburg functional response demonstrates quasi-periodic fluctuations in a narrow parametric aria with a high predator growth rate and low prey growth rate. The quasi-periodic dynamics regions in the model with the Holling type III functional response correspond to the conception of fast and slow variables, however in this case, the stability of the system increases, and the Neimark-Sacker bifurcation occurs even at a higher growth rate of zooplankton.
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Fan, Wuhou, Yong Jin, and Liangjie Shi. "Mechanically robust and tough waterborne polyurethane films based on diselenide bonds and dual H-bonding interactions with fast visible-light-triggered room-temperature self-healability." Polymer Chemistry 11, no. 34 (2020): 5463–74. http://dx.doi.org/10.1039/d0py00897d.
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A dynamic but mechanically robust and tough polymer network was proposed, in which the fast room-temperature self-healing of our target polymer with mechanically robust and tough features is achieved under visible light.
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Zabolotnaya, Ekaterina, Ioanna Mela, Mark J. Williamson, Sian M. Bray, Siu Kei Yau, Dimitra Papatziamou, J. Michael Edwardson, Nicholas P. Robinson, and Robert M. Henderson. "Modes of action of the archaeal Mre11/Rad50 DNA-repair complex revealed by fast-scan atomic force microscopy." Proceedings of the National Academy of Sciences 117, no. 26 (June 15, 2020): 14936–47. http://dx.doi.org/10.1073/pnas.1915598117.
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Mre11 and Rad50 (M/R) proteins are part of an evolutionarily conserved macromolecular apparatus that maintains genomic integrity through repair pathways. Prior structural studies have revealed that this apparatus is extremely dynamic, displaying flexibility in the long coiled-coil regions of Rad50, a member of the structural maintenance of chromosome (SMC) superfamily of ATPases. However, many details of the mechanics of M/R chromosomal manipulation during DNA-repair events remain unclear. Here, we investigate the properties of the thermostable M/R complex from the archaeonSulfolobus acidocaldariususing atomic force microscopy (AFM) to understand how this macromolecular machinery orchestrates DNA repair. While previous studies have observed canonical interactions between the globular domains of M/R and DNA, we observe transient interactions between DNA substrates and the Rad50 coiled coils. Fast-scan AFM videos (at 1–2 frames per second) of M/R complexes reveal that these interactions result in manipulation and translocation of the DNA substrates. Our study also shows dramatic and unprecedented ATP-dependent DNA unwinding events by the M/R complex, which extend hundreds of base pairs in length. Supported by molecular dynamic simulations, we propose a model for M/R recognition at DNA breaks in which the Rad50 coiled coils aid movement along DNA substrates until a DNA end is encountered, after which the DNA unwinding activity potentiates the downstream homologous recombination (HR)-mediated DNA repair.
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Chen, Xue-Qing, and Lei Tong. "Multiscale flow characteristics of droplet spreading with microgravity conditions." Canadian Journal of Physics 97, no. 8 (August 2019): 869–74. http://dx.doi.org/10.1139/cjp-2018-0474.
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In this paper, mesoscopic lattice–Boltzmann method (LBM) and microscopic molecular dynamics simulation method were used to simulate droplet dynamic wetting under microgravity. In terms of LBM, the wetting process of a droplet on a solid wall surface was simulated by introducing the fluid–fluid and solid–fluid interactions. In terms of molecular dynamics simulation, the spreading process of water on gold surface was simulated. Calculation results showed that two kinds of calculation methods were based on the microscopic molecular theory or mesoscopic kinetics theory, and such models could effectively overcome the contact line paradox issue, which results from the macro-continuum assumption and non-slip boundary condition assumption. The spreading exhibits two-stage behavior: fast spreading and slow spreading stages. For the two simulation methods, the ratio of fast spreading stage duration to slow spreading duration, spreading capacity (equilibrium contact radius/initial radius), and the spreading exponent of the rapid stage were very close. However, the predictive spreading index of the slow spreading stage was different, owing to the different spreading mechanisms between meso- and nanoscales.
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Rigo, Richard, J�r�mie Bazin, Martin Crespi, and C�line Charon. "Alternative Splicing in the Regulation of Plant–Microbe Interactions." Plant and Cell Physiology 60, no. 9 (May 20, 2019): 1906–16. http://dx.doi.org/10.1093/pcp/pcz086.
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Abstract As sessile organisms, plants are continuously exposed to a wide range of biotic interactions. While some biotic interactions are beneficial or even essential for the plant (e.g. rhizobia and mycorrhiza), others such as pathogens are detrimental and require fast adaptation. Plants partially achieve this growth and developmental plasticity by modulating the repertoire of genes they express. In the past few years, high-throughput transcriptome sequencing have revealed that, in addition to transcriptional control of gene expression, post-transcriptional processes, notably alternative splicing (AS), emerged as a key mechanism for gene regulation during plant adaptation to the environment. AS not only can increase proteome diversity by generating multiple transcripts from a single gene but also can reduce gene expression by yielding isoforms degraded by mechanisms such as nonsense-mediated mRNA decay. In this review, we will summarize recent discoveries detailing the contribution of AS to the regulation of plant–microbe interactions, with an emphasis on the modulation of immunity receptor function and other components of the signaling pathways that deal with pathogen responses. We will also discuss emerging evidences that AS could contribute to dynamic reprogramming of the plant transcriptome during beneficial interactions, such as the legume–symbiotic interaction.
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Yan, Fa Suo, Hong Wei Wang, Jun Zhang, and Da Gang Zhang. "Influence of Wind Turbine Aero-Elastic Load on Dynamic Response of Floating Platform." Advanced Materials Research 608-609 (December 2012): 649–52. http://dx.doi.org/10.4028/www.scientific.net/amr.608-609.649.
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A numerical code, known as COUPLE, which has been developed to perform hydrodynamic analysis of floating body with a mooring system, is extended to collaborate with FAST to evaluate the interactions between wind turbine and its floating base. FAST is developed by National Renewable Energy Lab (NREL) for aeroelastic simulation of wind turbines. A dynamic response analysis of a spar type floating wind turbine system is carried out by the method. Two types of simulation of wind load are used in the analysis. One type is a constant steady force and the other is a six-component dynamic load from a turbulent wind model. Numerical results of related platform motions under random sea conditions are presented in time and frequency domain. Comparison of results is performed to explain the difference of two analyses. The conclusions derived in this study may provide reference for the design of offshore floating wind turbines.
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Hassan, Normaziana binti, Syahrini Shawalludin, Juaini Jamaludin, and Adrian Chee. "Chasing Trends: The Dynamic Fashion Choices of Klang Valley Adolescents." International Journal of Research and Innovation in Social Science VIII, no. X (2024): 1186–97. http://dx.doi.org/10.47772/ijriss.2024.8100100.
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This study actively examines the fashion preferences of adolescents in Klang Valley, Malaysia, by highlighting the influences of local and global brands, streetwear culture, sustainability awareness, and the impact of social media and peer dynamics. Adolescents balance their support for local brands, like Fashion Valet, which embody national identity, with a preference for global fast-fashion brands, such as Zara and H&M, known for offering trendy and affordable clothing. Streetwear culture significantly shapes their self-expression, while sustainability is gaining importance, as thrift shopping becomes popular for its eco-friendly appeal. Social media platforms, especially Instagram and Tik Tok, play a crucial role in shaping fashion choices through influencer promotions and peer interactions, continually driving new trends. Peer influence further directs their preferences as adolescents seek both social acceptance and individuality within their social circles. Despite a rising interest in sustainable fashion, cost and accessibility still pose challenges, leading many adolescents to opt for fast fashion due to its affordability. The study reveals that adolescents in Klang Valley are shaped by a mix of cultural identity, global trends, and digital engagement, reflecting a dynamic and evolving fashion environment. The findings provide key insights into the factors driving adolescent fashion choices in Malaysia and enhance the understanding of youth consumer behavior in the region.
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Song, Peijian, Cheng Zhang, Yunjie Xu, Ling Xue, Ke Wang, and Chenghong Zhang. "Asymmetric Interaction in Competitive Internet Technology Diffusion." Journal of Global Information Management 19, no. 3 (July 2011): 45–64. http://dx.doi.org/10.4018/jgim.2011070103.
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This paper explores the diffusion of competitive Internet technology products in the context of competition between local and multinational corporations as well as how the diffusive interactions between technologies affect their dominance in electronic markets. Drawing on existing theories of innovation diffusion, and competitive dynamics, the authors adopted a new diffusion model that incorporates the influence of one technology’s adoption on the diffusion of other technology. The authors then validated the model using longitudinal field data of the two pairs of Internet technology products in Chinese electronic markets. The findings of this investigation suggest that Internet product diffusion can be better predicted by a competitive dynamic model than by an independent-diffusion-process model. Further, results indicate that the diffusive interaction between local and multinational corporations’ technologies can be a two-way asymmetric interaction. Such a pattern supports a conclusion of significant second-mover advantage for local online vendors in fast-growing emerging markets. The authors also examine the policy implications of these results, specifically with respect to how asymmetric interaction effects can help domestic online vendors gain second-mover advantage facing the entry of multinational corporations.
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Elgabarty, Hossam, Tobias Kampfrath, Douwe Jan Bonthuis, Vasileios Balos, Naveen Kumar Kaliannan, Philip Loche, Roland R. Netz, Martin Wolf, Thomas D. Kühne, and Mohsen Sajadi. "Energy transfer within the hydrogen bonding network of water following resonant terahertz excitation." Science Advances 6, no. 17 (April 2020): eaay7074. http://dx.doi.org/10.1126/sciadv.aay7074.
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Energy dissipation in water is very fast and more efficient than in many other liquids. This behavior is commonly attributed to the intermolecular interactions associated with hydrogen bonding. Here, we investigate the dynamic energy flow in the hydrogen bond network of liquid water by a pump-probe experiment. We resonantly excite intermolecular degrees of freedom with ultrashort single-cycle terahertz pulses and monitor its Raman response. By using ultrathin sample cell windows, a background-free bipolar signal whose tail relaxes monoexponentially is obtained. The relaxation is attributed to the molecular translational motions, using complementary experiments, force field, and ab initio molecular dynamics simulations. They reveal an initial coupling of the terahertz electric field to the molecular rotational degrees of freedom whose energy is rapidly transferred, within the excitation pulse duration, to the restricted translational motion of neighboring molecules. This rapid energy transfer may be rationalized by the strong anharmonicity of the intermolecular interactions.
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Plodpradit, Pasin, Van Dinh, and Ki-Du Kim. "Coupled Analysis of Offshore Wind Turbine Jacket Structures with Pile-Soil-Structure Interaction Using FAST v8 and X-SEA." Applied Sciences 9, no. 8 (April 19, 2019): 1633. http://dx.doi.org/10.3390/app9081633.
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The coupled analysis between a turbine in operating condition and a complex jacket support structure was formulated in this paper for the reliable evaluation of offshore wind turbine structures including pile-soil-structure interactions (PSSIs). Discussions on the theoretical and simulation aspects of the coupled analysis are presented. The dynamic coupled analysis was implemented in X-SEA program and validated with FAST v8 (fatigue, aerodynamics, structures and turbulence) developed by NREL, USA. By replacing the sub-structural module in the FAST with the component of offshore substructure in the X-SEA, the reaction forces and the turbine loads were calculated in each time step and the results from X-SEA were compared with that from FAST. It showed very good agreement with each other. A case study of a NREL 5MW offshore wind turbine on a jacket support structure was performed. Coupled dynamic analyses of offshore wind turbine and support structures with PSSI were carried out. The results showed that in the coupled analysis, the responses of the structure are significantly less than in the uncoupled analysis. The support structure considering PSSI exhibited decreased natural frequencies and more flexible responses compared to the fixed-support structure. The implemented coupled analysis including PSSI was shown to be more accurate and computationally efficient.
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Miszta, Przemysław, Paweł Pasznik, Szymon Niewieczerzał, Jakub Jakowiecki, and Sławomir Filipek. "GPCRsignal: webserver for analysis of the interface between G-protein–coupled receptors and their effector proteins by dynamics and mutations." Nucleic Acids Research 49, W1 (June 1, 2021): W247—W256. http://dx.doi.org/10.1093/nar/gkab434.
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Abstract GPCRsignal (https://gpcrsignal.biomodellab.eu/) is a webserver devoted to signaling complexes of G-protein–coupled receptors (GPCRs). The recent improvement in cryo-electron microscopy resulted in the determination of a large number of high-resolution structures of GPCRs bound to their effector proteins: G proteins or arrestins. Analyzing the interfaces between receptor and an effector protein is of high importance since a selection of proper G protein or specific conformation of arrestin leads to changes of signaling that can significantly affect action of drugs. GPCRsignal provides a possibility of running molecular dynamics simulations of all currently available GPCR-effector protein complexes for curated structures: wild-type, with crystal/cryo-EM mutations, or with mutations introduced by the user. The simulations are performed in an implicit water-membrane environment, so they are rather fast. User can run several simulations to obtain statistically valid results. The simulations can be analyzed separately using dynamic FlarePlots for particular types of interactions. One can also compare groups of simulations in Interaction frequency analysis as HeatMaps and also in interaction frequency difference analysis as sticks, linking the interacting residues, of different color and size proportional to differences in contact frequencies.
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Schmidt, Clinton T., and Timothy J. Garrett. "A Simple Framework for the Dynamic Response of Cirrus Clouds to Local Diabatic Radiative Heating." Journal of the Atmospheric Sciences 70, no. 5 (April 23, 2013): 1409–22. http://dx.doi.org/10.1175/jas-d-12-056.1.
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Abstract This paper presents a simple analytical framework for the dynamic response of cirrus to a local radiative flux convergence, expressible in terms of three independent modes of cloud evolution. Horizontally narrow and tenuous clouds within a stable environment adjust to radiative heating by ascending gradually across isentropes while spreading sufficiently fast that isentropic surfaces stay nearly flat. Alternatively, optically dense clouds experience very concentrated heating, and if they are also very broad, they develop a convecting mixed layer. Along-isentropic spreading still occurs, but in the form of turbulent density currents rather than laminar flows. A third adjustment mode relates to evaporation, which erodes cloudy air as it lofts, regardless of its optical density. The dominant mode is determined from two dimensionless numbers, whose predictive power is shown in comparisons with high-resolution numerical cloud simulations. The power and simplicity of the approach hints that fast, subgrid-scale radiative–dynamic atmospheric interactions might be efficiently parameterized within slower, coarse-grid climate models.