Finding Communities by Their Centers

Abstract

Detecting communities or clusters in a real-world, networked system is of considerable interest in various fields such as sociology, biology, physics, engineering science, and interdisciplinary subjects, with significant efforts devoted in recent years. Many existing algorithms are only designed to identify the composition of communities, but not the structures. Whereas we believe that the local structures of communities can also shed important light on their detection. In this work, we develop a simple yet effective approach that simultaneously uncovers communities and their centers. The idea is based on the premise that organization of a community generally can be viewed as a high-density node surrounded by neighbors with lower densities, and community centers reside far apart from each other. We propose so-called “community centrality” to quantify likelihood of a node being the community centers in such a landscape, and then propagate multiple, significant center likelihood throughout the network via a diffusion process. Our approach is an efficient linear algorithm, and has demonstrated superior performance on a wide spectrum of synthetic and real world networks especially those with sparse connections amongst the community centers.

Exploration of Capturing CO2 from Flue Gas by Calcite Slit‐Nanopores: A Computational Investigation

“…For the adsorption of CO 2 , as the pore size increasing, it reveals three adsorption layers (pore width 10 Å), four adsorption layers (pore width~15 Å) and five adsorption layers (pore width �~20 Å), of which the density of the layers close onto the pore surface is large and decreases away from the pore surface to the central part of the pore. The density distribution of CO 2 in calcite slit-nanopores as the pore size changing is similar with the characteristic of CO 2 adsorbed in graphite slit-nanopores, [25] while which is different from the adsorption of CO 2 in slit-nanopores donated by clay mineral, [26] these differences can be attributed to the different surface characteristics that generating different adsorption properties of CO 2 in various nanopores. While for the adsorption of N 2 in calcite slit-nanopores, it gives out a variation form two adsorption layers (pore width~10 Å) to three adsorption layers (pore width �~15 Å), which is in agreement with the N 2 adsorption in clay slit-nanopores, [26] due to the weak adsorption interaction between the N 2 molecules with the pore surfaces.…”

Strong pairing in two dimensions: pseudogaps, domes, and other implications

“…(5) leads to an over estimate of particle-hole symmetry and may be in part responsible for the differences from the QMC data. Additionally, the absence of particle-hole fluctuations, as in generic T -matrix approaches, may lead to over estimates of the transition temperature and pairing gap [41,42]. Also important may be short-ranged charge density wave fluctuations which are neglected in the present study.…”

Probing nonclassicality under dissipation

“…It is observed that the nonclassicality of the open system will be wiped out if we allow the system to evolve under the environment for a long time before performing the measurements. For experimental investigation of the nonclassicality or quantumness through Leggett-Garg inequality, we propose to consider a two level quantum emitter (a solid state qubit) positioned close to a two-dimensional metaldielectric interface [35][36][37] keeping in mind the physical motivation to consider Lorentzian spectral density. The quantum emitter coupled to the metal-surface electromagnetic modes can be described by the Hamiltonian (1), and the problem can be solved exactly using Wigner-Weisskopf approach as discussed in Sec.…”