Publications

@article{b,
title = {Stationary Growth and Unique Invariant Harmonic Measure of Cylindrical Diffusion Limited Aggregation},
author = {Riccardo Marchetti and Alessandro Taloni and Emanuele Caglioti and Vittorio Loreto and Luciano Pietronero},
url = {http://prl.aps.org/},
year = {2012},
date = {2012-01-01},
journal = {PHYSICAL REVIEW LETTERS},
volume = {109},
publisher = {AMER PHYSICAL SOC},
abstract = {We prove that the harmonic measure is stationary, unique, and invariant on the interface of diffusion limited aggregation (DLA) growing on a cylinder surface. We provide a detailed theoretical analysis puzzling together multiscaling, multifractality, and conformal invariance, supported by extensive numerical simulations of clusters built using conformal mappings and on a lattice. The growth properties of the active and frozen zones are clearly elucidated. We show that the unique scaling exponent characterizing the stationary growth is the DLA fractal dimension.},
keywords = {caglioti, complex_systems, loreto, marchetti, pietronero, taloni},
pubstate = {published},
tppubtype = {article}
}

@article{b,
title = {Editorial},
author = {Vittorio Loreto and Luciano Pietronero and Stefano Zapperi},
url = {http://link.springer.com/content/pdf/10.1140%2Fepjb%2Fe2008-00319-2.pdf
http://www.scopus.com/inward/record.url?eid=2-s2.0-53149153877&partnerID=65&md5=2e0f94184809a0100dc4f96bc3781099
http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=000259677600001&DestLinkType=FullRecord&DestApp=ALL_WOS&UsrCustomerID=0c7ff228ccbaaa74236f48834a34396a},
year = {2008},
date = {2008-01-01},
journal = {THE EUROPEAN PHYSICAL JOURNAL. B, CONDENSED MATTER PHYSICS},
volume = {64(3-4)},
pages = {301--305},
keywords = {loreto, pietronero, statistical_physics, zapperi},
pubstate = {published},
tppubtype = {article}
}

@article{b,
title = {Space-time correlations of earthquakes},
author = {Patrizia Toris and Valerio De Rubeis and Vittorio Loreto and Luciano Pietronero},
url = {http://gji.oxfordjournals.org/content/173/3/932, http://www.scopus.com/inward/record.url?eid=2-s2.0-43449129493&partnerID=65&md5=781012778cff79bd9d3baf409098ca71
http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=000255708100014&DestLinkType=FullRecord&DestApp=ALL_WOS&UsrCustomerID=0c7ff228ccbaaa74236f48834a34396a},
year = {2008},
date = {2008-01-01},
journal = {GEOPHYSICAL JOURNAL INTERNATIONAL},
volume = {173(3)},
pages = {932--941},
publisher = {Blackwell Science Limited:PO Box 88, Oxford OX2 0NE United Kingdom:011 44 1865 776868, 011 44 1865 206038, EMAIL: journals.cs@blacksci.co.uk, INTERNET: http://www.blackwell-science.com, Fax: 011 44 1865 721205},
abstract = {Seismicity is a complex process featuring non-trivial space-time correlations in which several forms of scale invariance have been identified. A frequently used method to detect scale-invariant features is the correlation integral, which leads to the definition of a correlation dimension separately in space and time. In this paper, we generalize this method with the definition of a space-time combined correlation integral. This approach allows us to analyse medium-strong seismicity as a point process, without any distinction among main, after or background shocks. The analyses performed on the catalogue of worldwide seismicity and the corresponding reshuffled version strongly suggest that earthquakes of medium-large magnitude are time clustered inside specific space-time regions. On the basis of this feature, we recognize a space-time domain statistically characterized by sequences' behaviour and a domain of temporal randomness. Then, focusing on the spatial distribution of hypocentres, we find another domain confined to short distances and characterized by a relatively high degree of spatial correlation. This spatial domain slowly increases with time: we interpret this as the 'afterevent' zone representing the set of all subsequent events located very near (about 30 km) to each reference earthquake and embedded on specific seismogenic structures such as faults planes.},
keywords = {clustering, correlation, derubeis, loreto, memory, persistence, pietronero, statistical seismology, statistical_physics, tosi},
pubstate = {published},
tppubtype = {article}
}

@article{b,
title = {Semiotic dynamics and collaborative tagging},
author = {Ciro Cattuto and Vittorio Loreto and Luciano Pietronero},
url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-33846811604&partnerID=65&md5=2c999e995248b00346e3529eddcd4365
http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=000244081000006&DestLinkType=FullRecord&DestApp=ALL_WOS&UsrCustomerID=0c7ff228ccbaaa74236f48834a34396a, http://www.pnas.org/content/104/5/1461},
year = {2007},
date = {2007-01-01},
journal = {PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA (PNAS)},
volume = {104},
pages = {1461--1464},
publisher = {The National Academy of Sciencs of the USA - 2101 CONSTITUTION AVE NW, WASHINGTON, DC 20418 USA},
abstract = {Collaborative tagging has been quickly gaining ground because of its ability to recruit the activity of web users into effectively organizing and sharing vast amounts of information. Here we collect data from a popular system and investigate the statistical properties of tag cooccurrence. We introduce a stochastic model of user behavior embodying two main aspects of collaborative tagging: (i) a frequency-bias mechanism related to the idea that users are exposed to each other's tagging activity; (ii) a notion of memory, or aging of resources, in the form of a heavy-tailed access to the past state of the system. Remarkably, our simple modeling is able to account quantitatively for the observed experimental features with a surprisingly high accuracy. This points in the direction of a universal behavior of users who, despite the complexity of their own cognitive processes and the uncoordinated and selfish nature of their tagging activity, appear to follow simple activity patterns.},
keywords = {cattuto, loreto, pietronero, techno_social_systems},
pubstate = {published},
tppubtype = {article}
}

@article{b,
title = {Conformal approach to cylindrical DLA},
author = {Alessandro Taloni and Emanuele Cagliori and Vittorio Loreto and Luciano Pietronero},
url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-37649026579&partnerID=65&md5=18e07a1e17966902ff4a2c6e9b9dadfc
http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=000241413300004&DestLinkType=FullRecord&DestApp=ALL_WOS&UsrCustomerID=0c7ff228ccbaaa74236f48834a34396a},
year = {2006},
date = {2006-01-01},
journal = {JOURNAL OF STATISTICAL MECHANICS: THEORY AND EXPERIMENT},
volume = {Art. n. P09004},
abstract = {We extend the conformal mapping approach elaborated for the radial diffusion limited aggregation model (DLA) to cylindrical geometry. We introduce in particular a complex function which allows a cylindrical cluster to be grown using as an intermediate step a radial aggregate. The aggregate grown exhibits the same self-affine features as the original cylindrical DLA. The specific choice of the transformation allows us to study the relationship between the radial and the cylindrical geometry. In particular the cylindrical aggregate can be seen as a radial aggregate with particles of size increasing with the radius. On the other hand, the radial aggregate can be seen as a cylindrical aggregate with particles of size decreasing with the height. This framework, which shifts the point of view from the geometry to the size of the particles, can open the way to more quantitative studies on the relationship between radial and cylindrical DLA.},
keywords = {caglioti, DLA, fractals, loreto, pietronero, self_organization, statistical_physics, taloni},
pubstate = {published},
tppubtype = {article}
}

@article{b,
title = {Space-time combined correlation integral and earthquake interactions},
author = {Patrizia Tosi and Valerio De Rubeis and Vittorio Loreto and Luciano Pietronero},
url = {http://www.annalsofgeophysics.eu/index.php/annals/article/view/4404
http://apps.webofknowledge.com/full_record.do?product=WOS&search_mode=GeneralSearch&qid=2&SID=Z16dIAaDdB7I@I66cOJ&page=1&doc=1},
year = {2004},
date = {2004-01-01},
journal = {ANNALS OF GEOPHYSICS},
volume = {47(6)},
pages = {1849--1854,tosi,derubeis},
publisher = {EDITRICE COMPOSITORI BOLOGNA},
abstract = {Scale invariant properties of seismicity argue for the presence of complex triggering mechanisms. We propose a new method, based on the space-time combined generalization of the correlation integral, that leads to a self-consistent visualization and analysis of both spatial and temporal correlations. The analysis has been applied on global medium-high seismicity. Results show that earthquakes do interact even on long distances and are correlated in time within defined spatial ranges varying over elapsed time. On that base we redefine the aftershock concept.},
keywords = {clustering, loreto, pietronero, seismicity, statistical_physics},
pubstate = {published},
tppubtype = {article}
}

@article{b,
title = {Local Rigidity in sandpile models},
author = {Sergio Ciliberti and Guido Caldarelli and Vittorio Loreto and Luciano Pietronero},
url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-41349104849&partnerID=65&md5=aacf73720b482187890036fa4974915f
http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=000177200600046&DestLinkType=FullRecord&DestApp=ALL_WOS&UsrCustomerID=0c7ff228ccbaaa74236f48834a34396a},
year = {2002},
date = {2002-01-01},
journal = {PHYSICAL REVIEW E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS},
volume = {66},
pages = {016133:1--016133:7},
keywords = {caldarelli, ciliberti, DLA, loreto, pietronero, self_organization, statistical_physics},
pubstate = {published},
tppubtype = {article}
}

@article{b,
title = {Local rigidity and self-organized criticality for avalanches},
author = {Raffaele Cafiero and Vittorio Loreto and Luciano Pietronero and Alessandro Vespignani and Stefano Zapperi},
url = {http://iopscience.iop.org/0295-5075/29/2/001;jsessionid=8822A74DE3C96358510326242C4AF4E3.c3
http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=A1995QC36900001&DestLinkType=FullRecord&DestApp=ALL_WOS&UsrCustomerID=0c7ff228ccbaaa74236f48834a34396a},
year = {1995},
date = {1995-01-01},
journal = {EUROPHYSICS LETTERS},
volume = {29},
pages = {111--116},
publisher = {EDITIONS PHYSIQUE},
abstract = {The general conditions for a sandpile system to evolve spontaneously into a critical state characterized by a power law distribution of avalanches or bursts are identified as: a) the existence of a stationary state with a global conservation law; b) long-range correlations in the continuum limit (i.e. Laplacian diffusive field); c) the existence of a local rigidity for the microscopic dynamics. These conditions permit a classification of the models that have been considered up to now and the identification of the local rigidity as a new basic parameter that can lead to various possible scenarios ranging continuously from SOC behaviour to standard diffusion.},
keywords = {cafiero, loreto, pietronero, self_organization, statistical_physics, vespignani, zapperi},
pubstate = {published},
tppubtype = {article}
}

@article{b,
title = {Renormalization group approach to the crtical behavior of the forest-fire model},
author = {Vittorio Loreto and Luciano Pietronero and Alessandro Vespignani and Stefano Zapperi},
url = {http://prl.aps.org/abstract/PRL/v75/i3/p465_1, http://www.scopus.com/inward/record.url?eid=2-s2.0-0000977225&partnerID=65&md5=4f03991047dc2820ef6c00a2e81b3c7d
http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=A1995RK33000028&DestLinkType=FullRecord&DestApp=ALL_WOS&UsrCustomerID=0c7ff228ccbaaa74236f48834a34396a},
year = {1995},
date = {1995-01-01},
journal = {PHYSICAL REVIEW LETTERS},
volume = {75},
pages = {465--468},
abstract = {We introduce a renormalization scheme for the one- and two-dimensional forest-fire model in order to characterize the nature of the critical state and its scale invariant dynamics. We show the existence of a relevant scaling field associated with a repulsive fixed point. This model is therefore critical in the usual sense because the control parameter has to be tuned to its critical value in order to get criticality. It turns out that this is not just the condition for a time scale separation. The critical exponents are computed analytically and we obtain ν = 1.0, τ = 1.0 and ν = 0.65, τ = 1.16, respectively, for the one- and two-dimensional cases, in very good agreement with numerical simulations.},
keywords = {DDRG, loreto, pietronero, self_organization, statistical_physics, vespignani, zapperi},
pubstate = {published},
tppubtype = {article}
}