Community detection algorithms: a comparative analysis

Uncovering the community structure exhibited by real networks is a crucial step towards an understanding of complex systems that goes beyond the local organization of their constituents. Many algorithms have been proposed so far, but none of them has been subjected to strict tests to evaluate their performance. Most of the sporadic tests performed so far involved small networks with known community structure and/or artificial graphs with a simplified structure, which is very uncommon in real systems. Here we test several methods against a recently introduced class of benchmark graphs, with heterogeneous distributions of degree and community size. The methods are also tested against the benchmark by Girvan and Newman and on random graphs. As a result of our analysis, three recent algorithms introduced by Rosvall and Bergstrom, Blondel et al. and Ronhovde and Nussinov, respectively, have an excellent performance, with the additional advantage of low computational complexity, which enables one to analyze large systems.Comment: 12 pages, 8 figures. The software to compute the values of our general normalized mutual information is available at http://santo.fortunato.googlepages.com/inthepress

New analytic solutions of the collective Bohr hamiltonian for a beta-soft, gamma-soft axial rotor

New analytic solutions of the quadrupole collective Bohr hamiltonian are proposed, exploiting an approximate separation of the beta and gamma variables to describe gamma-soft prolate axial rotors. The model potential is a sum of two terms: a beta-dependent term taken either with a Coulomb-like or a Kratzer-like form, and a gamma-dependent term taken as an harmonic oscillator. In particular it is possible to give a one parameter paradigm for a beta-soft, gamma-soft axial rotor that can be applied, with a considerable agreement, to the spectrum of 234U.Comment: (Dipartimento di Fisica ``G.Galilei'' and INFN, via Marzolo 8, I-35131 Padova, Italy) 10 pages, 3 figure

A flexible and highly sensitive pressure sensor based on a PDMS foam coated with graphene nanoplatelets

The demand for high performance multifunctional wearable devices is more and more pushing towards the development of novel low-cost, soft and flexible sensors with high sensitivity. In the present work, we describe the fabrication process and the properties of new polydimethylsiloxane (PDMS) foams loaded with multilayer graphene nanoplatelets (MLGs) for application as high sensitive piezoresistive pressure sensors. The effective DC conductivity of the produced foams is measured as a function of MLG loading. The piezoresistive response of the MLG-PDMS foam-based sensor at different strain rates is assessed through quasi-static pressure tests. The results of the experimental investigations demonstrated that sensor loaded with 0.96 wt.% of MLGs is characterized by a highly repeatable pressure-dependent conductance after a few stabilization cycles and it is suitable for detecting compressive stresses as low as 10 kPa, with a sensitivity of 0.23 kPa−1, corresponding to an applied pressure of 70 kPa. Moreover, it is estimated that the sensor is able to detect pressure variations of ~1 Pa. Therefore, the new graphene-PDMS composite foam is a lightweight cost-effective material, suitable for sensing applications in the subtle or low and medium pressure ranges

TFF (v.4.1): A Mathematica Notebook for the Calculation of One- and Two-Neutron Stripping and Pick-Up Nuclear Reactions

The program TFF calculates stripping single-particle form factors for one-neutron transfer in prior representation with appropriate perturbative treatment of recoil. Coupled equations are then integrated along a semiclassical trajectory to obtain one- and two-neutron transfer amplitudes and probabilities within first- and second-order perturbation theory. Total and differential cross-sections are then calculated by folding with a transmission function (obtained from a phenomenological imaginary absorption potential). The program description, user instructions and examples are discussed

Return migration to home country: a systematic literature review with text mining and topic modelling

A crucial (and less developed) part of migration studies is the exploration of migrant’s further mobility and the intention of return to home country at some point in life. Knowing who, why and when returns matters for both the host and the home country. Very few studies have focused on return in a wider perspective, adopting a comparative approach. The present study aims at providing a systematic review of peer-reviewed literature indexed in Scopus database, to understand how return has been dealt with by researchers. The main objectives are: collecting and synthetizing previous studies; comparing approaches, conceptualizations of return, methods and variable of interest. A bibliometric analysis on metadata and content analysis based on text mining and topic modelling techniques has been conducted on a sample of approximately 3,000 publications. With our contribution, we expect to implement a baseline for theoretical development and empirical research, presenting an overview on the evolution of trend topics, with regional and temporal patterns of research focus and identifying knowledge gaps in literature

Quantum phase transitions in odd-A nuclei: The effect of the odd particle from spherical to oblate shapes

Quantum shape-phase transitions in odd-nuclei are investigated within the framework of the interacting boson-fermion model (IBFM). We consider the case of a single-j fermion coupled to an even-even boson core that performs a transition from spherical to oblate shapes varying a control parameter in the boson Hamiltonian. The aim of this work is to see the effect of the coupling of the unpaired fermion on the transition, to understand how the coupled single particle modifies the geometric shape of the system and how each of the odd states behaves when the boson core shifts along the transitional path.Scientific and Technical Research Council of Turkey BIDEB-2224AMinisterio de Economía y Competitividad FIS2011-28738- c02-01, CSD2007-00042Junta de Andalucía FQM160, P11-FQM-763

Benchmarks for testing community detection algorithms on directed and weighted graphs with overlapping communities

Many complex networks display a mesoscopic structure with groups of nodes sharing many links with the other nodes in their group and comparatively few with nodes of different groups. This feature is known as community structure and encodes precious information about the organization and the function of the nodes. Many algorithms have been proposed but it is not yet clear how they should be tested. Recently we have proposed a general class of undirected and unweighted benchmark graphs, with heterogenous distributions of node degree and community size. An increasing attention has been recently devoted to develop algorithms able to consider the direction and the weight of the links, which require suitable benchmark graphs for testing. In this paper we extend the basic ideas behind our previous benchmark to generate directed and weighted networks with built-in community structure. We also consider the possibility that nodes belong to more communities, a feature occurring in real systems, like, e. g., social networks. As a practical application, we show how modularity optimization performs on our new benchmark.Comment: 9 pages, 13 figures. Final version published in Physical Review E. The code to create the benchmark graphs can be freely downloaded from http://santo.fortunato.googlepages.com/inthepress

Psicología ambiental y bienestar

La investigación de nuestra tesis doctoral se propone demostrar desde un análisis científico el problema social referido a la habitabilidad de la vivienda y a la vivencia del ambiente urbano, cómo vive la generalidad de la población el,problema de la vivienda, su grandeza o su extrechura, cómo todo ello manifiesta una influencia del tipo psicológico, denominado “influencia habitativa”. “Influencia de la vivienda” en las personas. La “vivienda”, propia o alquilada, pequeña o grande, céntrica o alejada de la población, moderna o antigua, comoda o insegura, es y significa mucho mas que el termino “vivienda”. Es la casa, el “nido” de crecimiento y de realización, es el nucleo de referencia, de seguridad, de protección. Es el centro de felicidad o de infelicidad. En la casa se nace, en la casa se vive, en la casa se muere. Qué y cómo se perciba la vivienda en su referencia o seguridad es algo que influye en el mundo personal de cada uno y condiciona la personalidad, asi como la personalidad condiciona el tipo de vivienda que uno desea tener. En nuestra investigación utilizamos una metodología deductiva, investigativa, descriptiva y analítica, una perspectiva cuantificadora sobre la influencia psicológica generada en la población como consecuencia del vivir en una vivienda o en otra. Todo el trabajo trata de medir los problemas críticos actuales del ambiente: ambiente, vivienda, casa, habitantes, población, influencia, perspectiva habitacional. Citando a Thomas Mann (arquitecto francés que se ocupa del psicoanálisis), el cual afirma (1955), che Ningún hombre es una isla, podemos hablar de la influencia de la interacción entre los individuos, el contacto con el ambiente y con la naturaleza, para tratar de encontrase con el bienestar. El ambiente y la arquitectura han influido fundamentalmente en la formación de nuestra identidad, nuestro pensamiento y nuestras emociones. Al mismo tiempo, el hombre es el ser que más que cualquier otro ser puede modificar el ambiente para adaptarlo a sus propias necesidades, realizando cambios en el terreno y elecciones arquitectónicas. En esta investigación, mediante un cuidadoso análisis metodológico deductivo, descriptivo, analítico y electivo, se ha indagado sobre la relación entre el ambiente habitativo, el malestar de la influencia habitacional y psicológica que se genera en la población y las causas socio políticas que las provocan. El tema ha sido motivado por la evidente situación de sufrimiento que acompaña a gran parte de la población que no posee una casa de su propiedad, y de cómo, muy a menudo, se encuentran insatisfechos de su propia vivienda, de su propio ambiente y de la política habitacional, generando esto último una fuerte disparidad entre territorios, trastornos y contrastes entre los pobladores. El trabajo empírico se ha llevado a cabo sobre una muestra de 274 individuos (135 hombres 139 mujeres), residentes en todo el territorio regional de Sicilia. Se suminsitro un cuestionario con el propósito de alcanzar resultados sobre los grados de conciencia de la situación actual del estado de insatisfacción habitacional que se ha generado a través del tiempo en la población. La muestra seleccionada, se encuentra formada por individuos de diversas extracciones sociales, condiciones económicas, sexos, y por edades. Del análisis de los datos, ha resultado una correlación significativa entre el ambiente habitacional, conjuntamente con la políticas del sector, y la personalidad psicológica de los sujetos incluidos en las muestras.The aim of the research is to show as, by an accurate analysis of the social problems connected to the habitability of the lodging and to a good life in the habitat, we highlight the development in the people, of a psychological influential state, named house influence. We use a deductive, investigative, descriptive, analytic and perspective methodology to quantify the psychologic influence produced on the people as the living effect. The whole work is oriented to get over the influential critical problems increasing today: environment, habitation, house, inhabitants, people, influence, living welfare. Quoting Thomas Mann (a French architect who deals with psychoanalysis) who asserts (1955) that 'No Man is an Island', we can affirm the influence of the interactions among the individuals, the connection with the environment and nature about man's welfare. The environment and the architecture have fundamental influences to build up our identity, our thoughts and our emotions. At the same time, man is the human being who, more than others, can modify the environment to adapt it to own aims through territory changings and architectural choises. In this investigation, through a methodological deductive, descriptive, analytic, and perspective thorough analysis, it was investigated the relationship between the living habitat, the living and psychologic influential discomfort generated in the population and the sociopolitical causes that give use to it. The theme was motivated by the evident pain condition that unites a large part of the population without the possession of a house, and those who, often unsatisfied with own house, own habitat and the living policy, the latter causing a heavy difference among the territories, alterations and contrasts among the people. The empiric research was carried out on a sample of 274 people (135 men and 139 women) resident all over the Sicilian regional territory. Such a work had the aim to make clear and to know the present situation of the state of living dissatisfaction generated in the years on the people. The chosen sample, was picked out among several social origins, economic conditions, sex, age. By the data analysis, it emerged an important correlation between the living habitat, together with the sector policy, and the psychological discomfort of the sample subjects