Asymptotic analysis of first passage time in complex networks

The first passage time (FPT) distribution for random walk in complex networks is calculated through an asymptotic analysis. For network with size $N$ and short relaxation time $\tau\ll N$, the computed mean first passage time (MFPT), which is inverse of the decay rate of FPT distribution, is inversely proportional to the degree of the destination. These results are verified numerically for the paradigmatic networks with excellent agreement. We show that the range of validity of the analytical results covers networks that have short relaxation time and high mean degree, which turn out to be valid to many real networks.Comment: 6 pages, 4 figures, 1 tabl

Electronic Structure in Gapped Graphene with Coulomb Potential

In this paper, we numerically study the bound electron states induced by long range Coulomb impurity in gapped graphene and the quasi-bound states in supercritical region based on the lattice model. We present a detailed comparison between our numerical simulations and the prediction of the continuum model which is described by the Dirac equation in (2+1)-dimensional Quantum Electrodynamics (QED). We also use the Fano's formalism to investigate the quasi-bound state development and design an accessible experiments to test the decay of the supercritical vacuum in the gapped graphene.Comment: 5 page, 4 figure

Topological correlations in soap froths

Correlation in two-dimensional soap froth is analysed with an effective potential for the first time. Cells with equal number of sides repel (with linear correlation) while cells with different number of sides attract (with NON-bilinear) for nearest neighbours, which cannot be explained by the maximum entropy argument. Also, the analysis indicates that froth is correlated up to the third shell neighbours at least, contradicting the conventional ideas that froth is not strongly correlated.Comment: 10 Pages LaTeX, 6 Postscript figure

A state of the art of sensor location, flow observability, estimation, and prediction problems in traffic networks

A state-of-the-art review of flow observability, estimation, and prediction problems in traffic networks is performed. Since mathematical optimization provides a general framework for all of them, an integrated approach is used to perform the analysis of these problems and consider them as different optimization problems whose data, variables, constraints, and objective functions are the main elements that characterize the problems proposed by different authors. For example, counted, scanned or “a priori” data are the most common data sources; conservation laws, flow nonnegativity, link capacity, flow definition, observation, flow propagation, and specific model requirements form the most common constraints; and least squares, likelihood, possible relative error, mean absolute relative error, and so forth constitute the bases for the objective functions or metrics. The high number of possible combinations of these elements justifies the existence of a wide collection of methods for analyzing static and dynamic situations

Cluster Persistence: a Discriminating Probe of Soap Froth Dynamics

The persistent decay of bubble clusters in coarsening two-dimensional soap froths is measured experimentally as a function of cluster volume fraction. Dramatically stronger decay is observed in comparison to soap froth models and to measurements and calculations of persistence in other systems. The fraction of individual bubbles that contain any persistent area also decays, implying significant bubble motion and suggesting that T1 processes play an important role in froth persistence.Comment: 5 pages, revtex, 4 eps figures. To appear in Europhys. Let

Topological model of soap froth evolution with deterministic T2-processes

We introduce a topological model for the evolution of 2d soap froth. The topological rearrangements (T2 processes) are deterministic (unlike the standard stochastic model): the final topology depends on the areas of the neighboring cells. The new model gives agreement with experiments in the transient regime, where the previous models failed qualitatively, and also improves agreement in the scaling state.Comment: latex, 12 pages, 2 figure

The concerns and experiences of patients with lumbar spinal stenosis regarding prehabilitation and recovery after spine surgery: A qualitative study

Objectives To improve our understanding of patients’ perspectives regarding: (1) the decision making and prehabilitation before lumbar spinal stenosis (LSS) surgery; and (2) their postoperative experiences. Design Qualitative research with semi-structured interviews. Setting General community Participants Individuals received (n=10) and did not receive (n=15) prehabilitation before LSS surgery were recruited at the 6-month postoperative follow-up (8 females; average age: 67.7±6.7 years) by purposive sampling. Additionally, one participant invited her daughter to accompany her in an interview. Interventions Not applicable Main outcome measures Concerns and experiences of patients with LSS regarding prehabilitation and recovery after spine surgery. Results Thematic analysis was conducted to identify four themes inductively: (1) sources of information about LSS surgery; (2) factors affecting the surgical decision making; (3) attitudes toward prehabilitation; and (4) postoperative recovery. All participants desired to have more preoperative education to inform their surgical decision making. There were mixed opinions regarding the perceived benefits of prehabilitation because some individuals hesitated to participate in prehabilitaiotn due to their symptoms, or the cost or time of travelling. Many participants expected some or even complete relief of LSS-related symptoms after surgery. However, not all participants experienced the expected postoperative improvements. Some participants only experienced temporary symptomatic relief, while others experienced new postoperative symptoms. Patients generally found that postoperative exercises taught by physiotherapists were useful although their compliance decreased over time. Conclusions Our study highlights the need for better preoperative LSS education. Since face-to-face prehabilitation or postoperative rehabilitation may not be feasible for all patients, future studies should explore whether online-based prehabilitation or postoperative rehabilitation may benefit certain patient subgroups