Narrow Results

In recent years, the dynamic spread of information has captured researchers’ attention. Therefore, identifying influential spreaders of information has become a fundamental element of information spreading research. Many studies have measured the influence of spreaders by considering the centrality indexes of network topology characteristics, such as degree, betweenness and closeness centrality. Additionally, some works have identified influential spreaders by analyzing human mobility characteristics such as contact frequency, contact time and inter-contact time. In this paper, we mainly explore the influence of the step size and radius of gyration on information spreading. Using a real and large-scale dataset of human mobility, we apply the susceptible-infected-recovered (SIR) model to investigate the spread of information. The simulation result shows that the influence of information spreading does not increase with the increase in the step size or radius of gyration of spreaders. Instead, both the step size and radius of gyration have a great influence on the spread of information when they are near the median value. Regardless of whether they have a large or small value, their influence on the spread of information is small. Therefore, the step size and radius of gyration of spreaders can be used to control or guide the spread of information.

Accurate to the first order in the uniform angular velocity, the general relativistic frame dragging effect of the moments of inertia and the radii of gyration of two kinds of neutron stars are calculated in a relativistic σ – ω model. The calculation shows that the dragging effect will diminish the moments of inertia and radii of gyration.

In this study, the dispersion of aggregated boron nitride nanotubes (BNNTs) in aqueous triton X-100 surfactant solution is studied using molecular dynamic simulation. The results indicate that how in the presence of the surfactant, a space between two BNNTs is created, which leads to the dispersion of the BNNTs. The radial distribution functions (RDFs) of the atoms of BNNTs and hydrophilic and hydrophobic segments of the surfactant respect to atoms of water molecules show that in the presence of the surfactant, a layer of water molecules is located in the neighborhood of the BNNTs and then hydrophobic and hydrophilic segments of the surfactant reside at more distances of the BNNTs. In the absence of the surfactant, the hydrogen bond between nitrogen atom of the BNNT and hydrogen atom of water molecules is established and the distance between water molecules and the BNNTs is decreased with increase of the surfactant concentration. The obtained results for the surfactant radius of gyration and the interfacial angle between two BNNTs reveal more information about the arrangement of the surfactants around the BNNTs in the presence and in the absence of water molecules.

The application of graph theory in structural biology offers an alternative means of studying 3D models of large macromolecules such as proteins. The radius of gyration, which scales with exponent $\sim 0.4$, provides quantitative information about the compactness of the protein structure. In this study, we combine two proven methods, the graph-theoretical and the fundamental scaling laws, to study 3D protein models. This study shows that the mean node degree (MND) of the protein graphs, which scales with exponent 0.038, is scale-invariant. In addition, proteins that differ in size have a highly similar node degree distribution. Linear regression analysis showed that the graph parameters (radius, diameter, and mean eccentricity) can explain up to 90% of the total radius of gyration variance. Thus, the graph parameters of radius, diameter, and mean eccentricity scale match along with the same exponent as the radius of gyration. The main advantage of graph eccentricity compared to the radius of gyration is that it can be used to analyze the distribution of the central and peripheral amino acids/nodes of the macromolecular structure.

An improved configurational-confomational statistical method is developed and the mean-square radius of gyration for atactic poly(α-methylstyrene)(PαMS) chains is studied, in which the effect of large side groups is considered. The deduced formulas, based on the rotational isomer state theory, are used to investigate the configuration-dependent properties of the atactic polymer chain, and the statistical correlation of the unperturbed polymer chain dimension and structure parameters are calculated. For the fraction of meso dyads w_m = 0.4, the dependence of the radius of gyration R_g and the intrinsic viscosity [η] on the molecule mass M are R_g = 2.63 × 10^-2 M^0.50nm and [η] = 7.36 × 10^-2 M^0.497, respectively, which are in agreement with the previous experimental data for the (PαMS) samples. A small hump is detected in the curve of the characteristic ratio of the unperturbed mean-square radius of gyration versus the chain length for short (PαMS) chains. The R_g increases linearly with the temperature T, and the effects of the chain length and the tacticity on the temperature coefficient are remarkable. These are quite different from the results for (PαMS) chains not considering side groups or for the monosubstituted polystyrene chain.

The refractive index increment, dynamic and static laser light scattering, intrinsic viscosity [η] and Huggins constant (K_H) of nylon 12 have been measured in m-cresol and sulphuric acid/water system at 10–60°C. The intrinsic viscosity, R_H, R_g, A₂, and (< S >²)^1/2 (calculated from viscosity data) and "a" values of nylon 12 are found to be higher in m-cresol than in sulphuric acid. All these parameters decrease with the increase in water contents in sulphuric acid. The refractive index increment, K_H and activation energy show an opposite trend to that of [η]. The intrinsic viscosity, R_H, R_g, A₂, and (< S >²)^1/2 have maximum values around 30–40°C in sulphuric acid/water system, whereas in m-cresol they fall at about 20°C. It has been concluded that the variation in size, interaction parameter (second virial coefficient), [η] and K_H of the polymer solutions with the alteration in solvent composition and temperature are the out come of change in thermodynamic quality of solvents, selective adsorption, hydrogen bonding and conformational transitions. It has also been concluded that the increase in temperature first enhances the quality of the solvent, encourages hydrogen bonding and specific adsorption, and then deteriorates, bringing conformational transitions in the polymer molecules. However, the addition of water to sulphuric acid continuously deteriorates the solvent quality. This characteristic of the solvent system brings conformational changes in the polymer especially at low temperatures.

Taxis equipped with GPS can record their trajectory and generate huge amounts of data. We can analyzethe behavior of taxi drivers and search for similarities and common characteristics in their working patterns. In this paper, we utilize taxi GPS data collected form Tianjin city to analyze taxi drivers’ working pattern. Firstly, we determined taxis’ parking place by detecting stopping points and measured the operating range. Secondly, we studied the taxis’ working pattern by comparing the relationship between three representative locations in taxis’ behavior: parking place, working center and city center. Thirdly, we analyzed the spatial pattern from two perspectives of direction and distance. Lastly, we studied the income efficiency of different taxis from different parking places and working centers. The research results demonstrated that the taxis’ individual mobility behavior has clear similarities: The taxi drivers’ operating pattern has a characteristic of moving toward the city center andmost of the working centers distribute in positions between parking places and the city center. The discoveries are significant for urban public infrastructure construction, government’s management of the taxis and taxi drivers’ strategy selections.

The model of natural rubber (NR) was constructed using molecular dynamics simulation to study the effects of temperature on compression stress relaxation. The solubility parameter and cohesive energy density clearly proved the three-dimensional periodic molecular model does be able to reproduce bulk experimental data of the authentic material. The motion of the molecular chain in the wide temperature range of 273-418 K was described by various structural analysis parameters. The mean square radius of gyration, mean square displacement (MSD) and fractional free volume (FFV) were investigated, all of which increased with the temperature rising up. Compression stress relaxation experiment was also conducted under different temperatures. It was found that the stress relaxation coefficient decreased as the aging time and temperature increased. The results showed that experiment and simulation were in good consistent.