Two ISC researchers supported to turn their science into practice.
ISC researchers, E. Zaccarelli, S. Sennato in collaboration with I. Viola from CNR – NANOTEC won the ERC Proof-of-Concept grant with their project Microgel-nanoparticles colorimetric sensor for pesticide detection. This financial support will enable them to translate their pioneering research into tangible innovations.
More information can be found here.
ISC-Director José Lorenzana has recently collaborated on a compelling research work that appeared in Physical Review Letters. J. Lorenzana and G. Seibold, Long-Lived Higgs Modes in Strongly Correlated Condensates, Phys. Rev. Lett. 132, 026501 (2024).
Condensed matter physics and high-energy physics has cross fertilizing each other for decades. One paradigmatic example is superconductivity, where Anderson’s mechanism giving mass to the Goldstone mode in a superconductor was taken by Higgs to explain mass generation in the
Standard model of elementary particles.… Read the rest
ISC researcher Valentina Brosco coauthored an interesting research proposing a novel superconduting qubit desigm. The work has been selected for an Editor’s Suggestion in Physical Review Letters, see Superconducting Qubit Based on Twisted Cuprate Van der Waals Heterostructures V. Brosco, G. Serpico, V. Vinokur, N. Poccia and U. Vool, Phys. Rev. Lett. 132, 017003 (2024).
… Read the restAbstract
Van-der-Waals assembly enables the fabrication of novel Josephson junctions featuring an atomically sharp interface between two exfoliated and relatively twisted Bi2Sr2CaCu2O8+x (Bi2212) flakes.
ISC researchers F. Brasili, S. Sennato and E. Zaccarelli coauthored an interesting research published in ACS Applied Materials and Interfaces, Toward a Unified Description of the Electrostatic Assembly of Microgels and Nanoparticles, F. Brasili, G. Del Monte, A. Capocefalo, E. Chauveau, E. Buratti, S. Casciardi, D. Truzzolillo, S. Sennato, E. Zaccarelli ACS Appl. Mater. Interfaces, December 2023
ISC researcher, M. Cencini coauthored an interesting work recently published in Communications Physics, C. Calascibetta, L. Biferale, F. Borra, F. and M. Cencini, Optimal tracking strategies in a turbulent flow, Commun. Phys. 6, 256 (2023).
… Read the restAbstract
Pursuing a drifting target in a turbulent flow is an extremely difficult task whenever the searcher has limited propulsion and maneuvering capabilities. Even in the case when the relative distance between pursuer and target stays below the turbulent dissipative scale, the chaotic nature of the trajectory of the target represents a formidable challenge.
ISC Director, J. Lorenzana, coauthored an interesting work on Nano Letters, Enhanced Critical Field of Superconductivity at an Oxide Interface, Athby H. Al-Tawhid
A. H. Al-Tawhid, S. J. Poage, S. Salmani-Rezaie, A. Gonzalez, S. Chikara, D. A. Muller, D. P. Kumah, Maria N. Gastiasoro, J. Lorenzana, and K.… Read the rest
ISC researcher Valentina Brosco coauthored an interesting research article published in ACS Applied Materials and Interfaces, C. Saggau et al., 2D High-Temperature integration in Contact Printed Circuit Boards, ACS Appl. Mater. Interfaces 44, 51558 (2023). The work paves the way to the realization of novel printed circuits and devices integrating atomically thin high-Tc superconducting films.
… Read the restInherent properties of superconducting Bi2Sr2CaCu2O8+x films, such as the high superconducting transition temperature Tc, efficient Josephson coupling between neighboring CuO layers, and fast quasiparticle relaxation dynamics, make them a promising platform for advances in quantum computing and communication technologies.
ISC reseracher Nicoletta Gnan co-organize the interesting webinar series “Soft Discussions: Roads to the Isodays” covering various topics in soft matter.
Each webinar, of the duration of approximately 1 hour, cosists of two parts:
Part1 – Ask me Anything!
Our Ask Me Anything (AMA) session is a unique opportunity to interact with an internationally renowned scientist in the field of soft matter.
Le Ricercatrici Roberta Angelini e Barbara Ruzicka dell’Istituto dei Sistemi Complessi partecipano a Maker Faire Rome (https://makerfairerome.eu/it/anteprima/) nello stand Rome Technopole con un laboratorio interattivo rivolto principalmente agli studenti, ma adatto anche ad un pubblico generico, basato sulla manipolazione di diversi materiali soffici per scoprire di più sulle proprietà di questi materiali del futuro e sulle loro applicazioni.
ISC researcher S. Felicetti is the lead author of a research article now published in PRX Quantum, in collaboration with Aalto University (Helsinki) and the Institute of Fundamental Physics IFF-CSIC (Madrid): U. Alushi, T. Ramos, J.-J. G.-Ripoll, R. Di Candia, and S. Felicetti PRX Quantum 4, 030326 (2023).
Quadratic light-matter interactions are nonlinear couplings such that quantum emitters interact with photonic or phononic modes exclusively via the exchange of excitation pairs.… Read the rest
ISC researcher L. Fanfarillo coauthored an interesting article now published in Nature Communications, C. Setty, L. Fanfarillo and P. J. Hirschfeld Nat. Comm. 3181 (2023).
… Read the restIn weakly coupled BCS superconductors, only electrons within a tiny energy window around the Fermi energy, EF, form Cooper pairs. This may not be the case in strong coupling superconductors such as cuprates, FeSe, SrTiO3 or cold atom condensates where the pairing scale, EB, becomes comparable or even larger than EF.
In PRX Life Thermodynamics Reveals Coordinated Motors in Sperm Tails
Thermodynamic Limits of Sperm Swimming Precision, C. Maggi, F. Saglimbeni, V. Carmona Sosa, R. Di Leonardo, B. Nath, and A. Puglisi in PRX Life
… Read the restAbstract
Sperm swimming is crucial to fertilize the egg, in nature and in assisted reproductive technologies. Modeling the sperm dynamics involves elasticity, hydrodynamics, internal active forces, and out-of-equilibrium noise.
ISC researchers in collaboration with the University of Ferrara and University of Rome Tor Vergata recently published a beautiful research work, Molecular origin of the two-step mechanism of gellan aggregation, on Science Advances. The work provides the first microscopic overview of gellan aggregation detecting the coil to single-helix transition at dilute conditions and the formation of higher-order aggregates at high concentration.… Read the rest
ISC researcher Stefano Lepri and ISC associate Roberto Livi coauthored an interesting review article showing how heat flow is different on the nanoscale.
G. Benenti, D. Donadio, S. Lepri and R. Livi, Non Fourier heat transport in nanosystems, La Rivista del Nuovo Cimento (2023)
… Read the restEnergy transfer in small nano-sized systems can be very different from that in their macroscopic counterparts due to reduced dimensionality, interaction with surfaces, disorder, and large fluctuations.
ISC researcher Roberto Coccurello co-authored an interesting article on Brain Communications Passive immunotherapy for N-truncated tau ameliorates the cognitive deficits in two mouse Alzheimer’s disease models . The work was recently selected for the collection Brain sciences and the R words for its rigor, reproducibility and quality of the statistical analysis.
Clinical and neuropathological studies have shown that tau pathology better correlates with the severity of dementia than amyloid plaque burden, making tau an attractive target for the cure of Alzheimer’s disease.… Read the rest
Our colleagues Claudio Conti and Marcello Calvanese-Strinati have recently published a beautiful theoretical work showing how coupled parametric oscillators can simulate multidimensional continuous spin models. Read more on Nature Communications, 13 7248 (2022)
… Read the restAbstract
From condensed matter to quantum chromodynamics, multidimensional spins are a fundamental paradigm, with a pivotal role in combinatorial optimization and machine learning. Machines formed by coupled parametric oscillators can simulate spin models, but only for Ising or low-dimensional spins.
Stefano Boccaletti, researcher @ ISC – Firenze, coauthored an interesting work discussing how evolving pathogens impact the reproduction number and macroscopic dynamics of spreading processes. The article is also featured in the Applied Physics and Mathematics Focus page selecting “the most interesting papers published in Nature Communications in the interdisciplinary areas where diverse approaches at the boundaries of physics, mathematics, materials science and engineering take place to create new research opportunities”
Epidemic spreading under mutually independent intra- and inter-host pathogen evolution, X.… Read the rest
The prize Sergio Panizza e Gabriele Galimberti from the Italian Physical Society (SIF) was awarded to Dr.Davide Pierangeli, researcher in our Institute, “for his groudbreaking experimental work in the field of non-linear photonics. Among D. Pierangeli’s works, of particular relevance is the first observation of the breaking of replica symmetry in disordered photorefractive media.”
The original work D. Pierangeli, A. Tavani, F.… Read the rest
ISC researchers L. Pilozzi and V. Brosco write on a recent experiment [1] with photonic waveguides which demonstrates the connection between non-Abelian holonomies and adiabatic particle transport, paving the way to the geometric and topological control of light trajectories.
The experiment by Sun and colleagues represents one of the few observations so far of the non-Abelian Wilczek–Zee holonomy. But by employing Thouless pumping as a tool for probing non-Abelian topological physics, it also paves the way for the geometric control of photon states and light trajectories in real space — a fundamental step in the direction of photonic information processing [2].… Read the rest
Light can control microparticles and microstructures can shape light, leading to a wide range of practical applications as well as interesting physics.
By combining optically controlled micro-heaters with thermophilic particles attracted by them researchers form University College London obtained microlasers with programmable and reversible patterns. This achievement is a nice demonstration of what happens when colloidal science meets photonics and is now published in Nature Physics and highlighted by Neda Ghofraniha in News and Views .… Read the rest
The 2021 Impact Factor of Elsevier’s Chaos, Solitons and Fractals: the interdisciplinary journal of Nonlinear Science, and Nonequilibrium and Complex Phenomena is 9.922, ranking it 1 out of 108 in Mathematics, Interdisciplinary Applications.
ISC researchers strongly contributed to the success of Chaos, Solitons and Fractals, as Editors as well as Authors through publications of high scientific value. Congratulations to ISC researchers Stefano Lepri and Stefano Boccaletti who have been respectively Editor and Chief Editor of this journal for many years.
A Random Walk in Physics: Beyond Black Holes and Time-Travels is a book by
Massimo Cencini, Andrea Puglisi, Davide Vergni and Angelo Vulpiani.
Read a review in italian at Galileo… Read the rest
Andrea Ninarello, José Ruiz-Franco & Emanuela Zaccarelli have published Onset of criticality in hyper-auxetic polymer networks in Nature Communications volume 13, Article number: 527 (2022)
Against common sense, auxetic materials expand or contract perpendicularly when stretched or compressed, respectively, by uniaxial strain, being characterized by a negative Poisson’s ratio ν. The amount of deformation in response to the applied force can be at most equal to the imposed one, so that ν = − 1 is the lowest bound for the mechanical stability of solids, a condition here defined as “hyper-auxeticity”.… Read the rest
ISC director, Prof. Claudio Conti and Prof. Eugenio Del Re share their thoughts on the role of photonics experiments in the development of complex systems and spin glass theory. Read the full story on Nature Photonics News and Views.
… Read the restPhotonics and the Nobel Prize in Physics
Giorgio Parisi recently shared a Nobel Prize in Physics for his contribution to the theory of complex systems.
ISC researchers coauthored an interesting work on International Journal of Molecular Science,
Tau Cleavage Contributes to Cognitive Dysfunction in Strepto-Zotocin-Induced Sporadic Alzheimer’s Disease (sAD) Mouse Model
V. Latina et al. Int. J. Mol. Sci. 22, 12158 (2021)
Tau cleavage plays a crucial role in the onset and progression of Alzheimer’s Disease (AD), a widespread neurodegenerative disease whose incidence is expected to increase in the next years.… Read the rest
Claudio Conti and Eugenio Del Re co-authored an interesting work published on Nature Communications demonstrating experimentally self-induced topological transitions from elliptical to hyperbolic k-space manifolds in room-temperature photorefractive KTN.
… Read the rest
ISC researcher R. Coccurello coauthored an interesting article now published in Frontiers in Cell and developmental biology
L. Micheli, T. Creanza, M. Ceccarelli, G. D’Andrea, G. Giacovazzo, N. Ancona, R. Coccurello, R. Scardiglli, F.… Read the rest
ISC researchers, C. Conti, L. Pilozzi and V. Brosco, participate in the new PON project QUANCOM.
Security technologies in both the network transmission layers and in the application layers are becoming more and more complex and sophisticated but, nevertheless these efforts, they are not completely immune to attacks. In fact, even the computing power (parallel and distributed thanks to the network resource) is increasing and available to organizations that, for various purposes, have interests in appropriating of sensitive data.
ISC researchers working on soft matter coauthored a interesting work on the Proceedings of the National Academy of Science (PNAS)
Two-step deswelling in the Volume Phase Transition of thermoresponsive microgels
PNAS September 14, 2021 118 (37) e2109560118
Soft particles often combine colloidal and polymeric aspects, making them very valuable for both fundamental and applied science. Microgels, which are colloidal-scale polymer networks, are one of the most important examples in class of systems.… Read the rest
ISC associates Guido Caldarelli and Gulio Cimini coauthored an interesting review on modelling the financial systems and networks now published in Nature Reviews, M. Bardoscia, P. Barucca, S. Battiston, F. Caccioli, G. Cimini, D. Galaschelli, F. Saracco, T. Squartini, and G. Caldarelli. Nat. Rev. Phys. June (2021).
As the total value of the global financial market outgrew the value of the real economy, financial institutions created a global web of interactions that embodies systemic risks.… Read the rest
ISC researcher Stefano Focardi coauthored an interesting work in Science,”Mapping out a future for ungulate migrations” Science 372, 567 (2021).
The article shows how limited mapping of mammalians migrations hampers conservation and envisions a digital archive translating migration data into actionable migration maps that are standardized, in a central database, and publicly available.
Migration of ungulates (hooved mammals) is a fundamental ecological process that promotes abundant herds, whose effects cascade up and down terrestrial food webs.… Read the rest
ISC researcher Claudio Castellano and collaborators unveil the roles of contact tracing procedures in mitigating COVID-19 pandemic, now published in Nature Communications, see M. Mancasroppa, C. Castellano, A. Vezzani and R. Burioni, Stochastic sampling effects favor manual over digital contact tracing, Nature Communications 12, 1919 (2021).
Abstract
Isolation of symptomatic individuals, tracing and testing of their nonsymptomatic contacts are fundamental strategies for mitigating the current COVID-19 pandemic.… Read the rest
ISC Researcher Paola Verrucchi and Collaborators wrote a beatiful and elegant work investigating the concept of time in quantum mechanics, now published in Nature Communications, see C. Foti, A.Coppo, G. Barni, A. Cuccoli and P. Verrucchi, Time and classical equations of motion from quantum entanglement via the Page and Wootters mechanism with generalized coherent states, Nature Communications 12, 1787 (2021).
The figure shows the interaction between a classical clock and a quantum system.… Read the rest
Topological photonics has been opening exciting opportunities in recent optics research. This Special Issue provides a snapshot and overview of the recent advances in this thriving field of research. It features six papers and one review article, by some of the leading experts in the field, covering various aspects of topological photonics research.… Read the rest
ISC researcher V. Palmieri coauthored an article on NanoToday explaining the role of nanotechnologies in improving the performance of facial masks and warning on possible future consequences caused by a poorly regulated use of nanotechnology in textiles.
Coronavirus Disease 2019 (COVID-19) is one of the biggest challenges of the 21st century. While researchers are working on vaccine development and elucidating the mechanism of action and evolution of the harmful SARS-CoV-2, the current most important public health measure, second only to social distancing, is the obligatory wearing of facial protection.… Read the rest
ISC Researchers build for the first time replica symmetry breaking maps to visualize Random Laser activity on ACS Photonics 2021
In the past decade, complex networks of light emitters are proposed as novel platforms for photonic circuits and lab-on-chip active devices. Lasing networks made by connected multiple gain components and graphs of nanoscale random lasers (RLs) obtained from complex meshes of polymeric nanofibers are successful prototypes.… Read the rest
ISC researcher, Valentina Palmieri, and her collaborator M. Papi discuss the promising applications of functionalized graphene in the fight against COVID 19. Their research has been published in Nano Today, “Can graphene take part in the fight against COVID-19?“
Abstract
The pneumonia outbreak of coronavirus disease 2019 (COVID-19) represents a global issue.
Our researcher, Fabio Cecconi, has developed an analytical model elucidating the competition among electrophoresis, electroosmosis, and dielectrophoresis. The work is published on ACS Nano, M. Chinappi, Misa Yamaji, Ryuji Kawano, and Fabio Cecconi, “Analytical Model for Particle Capture in Nanopores Elucidates Competition among Electrophoresis, Electroosmosis, and Dielectrophoresis” ACS Nano, 14, 15816 (2020).
Abstract
The interaction between nanoparticles dispersed in a fluid and nanopores is governed by the interplay of hydrodynamical, electrical, and chemical effects.… Read the rest
Our staff researcher Roberta Angelini is Guest Editor of a Special Issue of Polymers on “Polymer Microgels: Synthesis and Application”
Polymer microgels have attracted great attention in fundamental studies as good model systems for understanding the intriguing behaviors of soft colloids thanks to their elastic and deformable particles that provide a very rich phenomenology. These cross-linked particles with nanometric to micrometric dimensions are characterized by many fascinating properties such as swelling, softness, and responsivity that depend on their macromolecular architecture and can be triggered during the synthesis process.… Read the rest
Antonio Maria Scarfone and co-authors have published The k-statistics approach to epidemiology in Scientific Reports 10, Article number: 19949 (2020)
G. Kaniadakis, M.M. Baldi, T.S. Deisboeck, G.Grisolia, D.T. Hristopulos, A.M. Scarfone, A. Sparavigna, T. Wada, U. Lucia
Keywords: Plague, Pandemics, Epidemics, -Statistics; -deformed Weibull; survival function
A great variety of complex physical, natural and artificial systems are governed by statistical distributions, which often follow a standard exponential function in the bulk, while their tail obeys the Pareto power law.… Read the rest
A. De Ninno, E. Nikollari, M. Missori and F. Frezza have published Dielectric permittivity of aqueous solutions of electrolytes probed by THz time-domain and FTIR spectroscopy in Physics Letters A.
Highlights
• The permittivity of water is described in terms of two independent Debye functions.
• The model is also applied to chloride solutions.
• The excess high frequency response is explained without ad hoc corrective terms.… Read the rest
Giulia Marcucci, Davide Pierangeli, and Claudio Conti have published Theory of Neuromorphic Computing by Waves: Machine Learning by Rogue Waves, Dispersive Shocks, and Solitons in Physical Review Letters.
Artificial neural networks with nonlinear waves as a computing reservoir are the subject of the paper in which the universality and the conditions to learn a dataset in terms of output channels and nonlinearity are discussed.… Read the rest
Fabrizio Camerin, Nicoletta Gnan, José Ruiz-Franco, Andrea Ninarello, Lorenzo Rovigatti, and Emanuela Zaccarelli have published Microgels at Interfaces Behave as 2D Elastic Particles Featuring Reentrant Dynamics
The properties and the structure of colloids—in which particles of one substance are dispersed in another—are determined by the way those particles interact with each other. An easy guess might lead one to say that complex particles possess an equally complex interaction potential.… Read the rest
Zhen Wang, Marko Jusup, Hao Guo,Lei Shi, Sunčana Geček, Madhur Anand, Matjaž Perc, Chris T. Bauch, Jürgen Kurths, Stefano Boccaletti, and Hans Joachim Schellnhuber have published
Communicating sentiment and outlook reverses inaction against collective risks
Collective risks trigger social dilemmas that require balancing selfish interests and common good. One important example is mitigating climate change, wherein without sufficient investments, worldwide negative consequences become increasingly likely.… Read the rest
Claudio Castellano and Romualdo Pastor-Satorras published this article in Phys. Rev. X 10, 011070 – Published 24 March 2020
Complex networks represent the interaction pattern for many real-world phenomena such as epidemic spreading. The simplest and most fundamental model for the diffusion of infectious diseases without acquired immunity predicts a vanishing epidemic threshold in the limit of large systems. In other words, no matter how small the infectiousness of the disease, there is always a finite fraction of the overall population which is infected for long times.… Read the rest
Massimo Cencini has published Alignment of Nonspherical Active Particles in Chaotic Flows in Physical Review Letters.
Active particles, such as motile microorganisms or artificial microswimmers, swim in a surrounding flow, either externally imposed or self-generated. Besides transporting the active particles, the flow velocity change their swimming direction by exerting a shape-dependent torque through the velocity gradients. The complex interplay of flow advection, particle orientation and self-propulsion is fundamental to understand key processes at the crossroad between aquatic ecology, active matter modeling, and nano/micro- technology with application to drug delivery.… Read the rest
Nicoletta Gnan and Emanuela Zaccarelli have published The microscopic role of deformation in the dynamics of soft colloids in Nature Physics.
Soft colloids enable the exploration of states with densities exceeding that of random close packing, but it remains unclear whether softness controls the dynamics under these dense conditions. Experimental studies have reported conflicting results, and numerical studies have so far focused primarily on simple models that allow particles to overlap, but neglect particle deformations.… Read the rest
Congratulations go to Paola Verrucchi and the co-authors of Quantum Measurement Cooling, recently published in Physical Review Letters, for having been selected as editor’s suggestion and featured article.
Physics.aps.org dedicates synopsis for the article as well.… Read the rest
A review article in the physics-central, physics-buzz blog has appeared presenting the recent results of G. Giacomelli, S. Lepri (ISC) and C.Trono (IFAC) about the LANER (lasing network):
http://physicsbuzz.physicscentral.com/2019/02/meet-laner-network-laser.html
https://journals.aps.org/pra/abstract/10.1103/PhysRevA.99.023841… Read the rest
Mauro Missori awarded a CNR Bilateral Agreement with the Chinese Academy of Cultural Heritage (CACH) with the project “Nanoscale degradation indexes of ancient Chinese and Italian papers for conservation & restoration applications”.
The aim of this joint research project is to develop degradation indexes of ancient Chinese and Italian papers for restoration applications. These activities require the use of specific physical and chemical diagnostics technique at the nanoscale suitable for the cellulose-based materials and, in general, for natural polymeric fibers.… Read the rest
Maxime J. Bergman, Nicoletta Gnan, Marc Obiols-Rabasa, Janne-Mieke Meijer, Lorenzo Rovigatti, Emanuela Zaccarelli & Peter Schurtenberger
Nature Communications volume 9, Article number: 5039 (2018)
Thermoresponsive microgels find widespread use as colloidal model systems, because their temperature-dependent size allows facile tuning of their volume fraction in situ.
However, an interaction potential unifying their behavior across the entire phase diagram is sorely lacking.… Read the rest
Letizia Tavagnacco, Emanuela Zaccarelli and others published Evidence of a low-temperature dynamical transition in concentrated microgels in Science Advances.
A low-temperature dynamical transition has been reported in several proteins. We provide the first observation of a “protein-like” dynamical transition in nonbiological aqueous environments. To this aim, we exploit the popular colloidal system of poly-N-isopropylacrylamide (PNIPAM) microgels, extending their investigation to unprecedentedly high concentrations.… Read the rest
Emanuela Zaccarelli awarded a MIUR FARE grant with the project SOFTART: Enhancing microgels potentialities: ultrasoftness and cultural heritage applications.
The project builds on the ERC Consolidator project MIMIC and combines theoretical/numerical expertise of the MIMIC team led by Emanuela Zaccarelli with experimental work at CNR ISC carried out by the groups of Barbara Ruzicka, Roberta Angelini, Simona Sennato and Mauro Missori.… Read the rest
Congratulations to Andrea Cavagna for winning an ERC Advanced Grant (panel PE2) with the project:
Renormalization group approach to the collective behaviour of strongly correlated biological systems (RG.BIO)
Biological systems displaying collective behaviour are characterized by strong spatio-temporal correlations, which partly transcend the multiform diversity of their microscopic details, much as it happens in statistical physics systems close to a critical point.… Read the rest
Metamaterials are engineered material having periodic structures that exhibit unique properties when they interact with electromagnetic waves in comparison with natural materials. They offer interesting applications throughout the electromagnetic spectrum and are crucial in the Terahertz (THz) frequency band which lies between microwave and infrared and thus invisible to the human eye. This band is a new frontier both for research and technological applications in sectors ranging from astronomy to cultural heritage.… Read the rest
A plate shearing an interstitial granular medium and driven by an always ongoing spring feels less fricion when only few layers are present. Adding more layers results in an increase of friction,
nevertheless the plate slides more often. The ease of slipping is not determined by friction alone?
M A Annunziata, A Baldassarri, F Dalton, A Petri and G Pontuale, Increasing ‘ease of sliding’ also increases friction: when is a lubricant effective?… Read the rest
The cascade of resonant PT-symmetric topological structures is shown to emit laser light with a frequency comb spectrum. We consider optically active topological lattices supporting edge modes at regularly spaced frequencies. When the amplified resonances in the PT-broken regime match the edge modes of the topological gratings, we predict the emission of discrete laser lines. A proper design enables the engineering of the spectral features for specific applications.… Read the rest
Massimo Cencini has published Energetic funnel facilitates facilitated diffusion in Nucleic Acid Research.
Gene transcription is regulated by proteins – Transcription Factors (TFs) – that by binding to short target sequences are able to promote or impede the binding of RNA-Polymerase (RNAP) and, consequently, activate or repress tran-
scription. Fast and accurate control of gene expression is crucial for many biological functions, and relies on the ability of TFs to rapidly find their transcription factor binding site (TFBS) among a multitude of competing DNA sequences,
and to establish with it a stable complex.… Read the rest
Davide Pierangeli, Andrea Tavani, Fabrizio Di Mei, Aharon J. Agranat, Claudio Conti & Eugenio DelRe have published an article Observation of replica symmetry breaking in disordered nonlinear wave propagation in nature communications.
Abstract
A landmark of statistical mechanics, spin-glass theory describes critical phenomena in disordered systems that range from condensed matter to biophysics and social dynamics. The most fascinating concept is the breaking of replica symmetry: identical copies of the randomly interacting system that manifest completely different dynamics.… Read the rest
Claudio Castellano has published Relating Topological Determinants of Complex Networks to Their Spectral Properties: Structural and Dynamical Effects in Physical Review X.
In many social and biological systems, the pattern of interactions is described by complex networks—mathematical constructions composed of points (vertices) representing individuals, joined by lines (edges), standing for pairwise interactions between them. These structures are important because they affect the behavior of the dynamical processes they mediate.… Read the rest
Congratulations to Nicoletta Gnan, Lorenzo Rovigatti, Maxime Bergman and Emanuela Zaccarelli whose article In Silico Synthesis of Microgel Particles has been selected as editor’s choice in Macromolecules.… Read the rest
In the biomedical field, Diffusion Magnetic Resonance (DMR) images provide a measure of water proton displacements by probing motion on the mesoscopic length scale (around 10-20 µm), which is orders of magnitude smaller than the macroscopic MR resolution (typically 1-2 millimetres for clinical MR scanners).
Therefore, independently of image resolution (which is linked to the hardware of the NMR scanner) we can obtain microstructural information of human tissue at the mesoscopic length scale.… Read the rest
Paolo Politi and Roberto Livi have published a book:
Nonequilibrium statistical physics: A modern perspective.
Statistical mechanics has been proven to be successful at describing physical systems at thermodynamic equilibrium. Since most natural phenomena occur in nonequilibrium conditions, the present challenge is to find suitable physical approaches for such conditions: this book provides a pedagogical pathway that explores various perspectives.… Read the rest
Congratulations to Paolo Politi whose letter Effective mobility and diffusivity in coarsening processes has been selected as editor’s choice in Europhysics Letters.… Read the rest
See also A Better Way to Make Economic Forecasts
Il 14 settembre alla Banca Mondiale di Washington
Questo evento è totalmente dedicato ai risultati e alle prospettive della collaborazione
tra il gruppo della Sapienza (Fisica) e dell’Istituto dei Sistemi Complessi del CNR,
coordinato dal Prof. Luciano Pietronero, con la World Bank.
Economic Fitness (EF) consiste in un nuovo paradigma sviluppato dal gruppo di
Pietronero in cui si descrivono le economie come processi evolutivi di ecosistemi di
tecnologie e infrastrutture industriali e finanziarie che sono globalmente
interconnesse.… Read the rest
Andrea Cavagna, Daniele Conti, Chiara Creato, Lorenzo Del Castello, Irene Giardina, Tomas S. Grigera, Stefania Melillo, Leonardo Parisi & Massimiliano Viale have published an article on the collective behaviour in biological systems which presents theoretical challenges beyond the borders of classical statistical physics.… Read the rest
Complex Active Optical Networks as a New Laser Concept by Stefano Lepri, Cosimo Trono and Giovanni Giacomelli has been published in Physical Review Letters.
The introduction of one or more active sections in a complex network may lead to laser emission. We call this system LANER (lasing network). As in the usual laser, when the gains are sufficiently high coherent emission is produced; in this case, the full network becomes a complicated, multipath and multigain cavity for the optical field.… Read the rest
A quantum analogue of the popular “Newton’s cradle” toy has been proposed by a duo of physicists in Italy. Like momentum transferred in the toy, the team argues that it should be possible to achieve the nearly perfect transmission of a quantum wavefunction along a line of ultracold atoms in a 1D Bose–Einstein condensate. According to the pair, the work could help develop quantum-information systems that achieve high-quality wave transmission […]
Newton’s cradle (Fig. 1) is a valuable paradigm of how physical mechanisms are concealed into nature. It is a device based on classical mechanics that demonstrates the conservation of momentum and energy. On the other hand, Quantum Mechanics has been shown to be one of most prolific sources of unexpected and hard-to-understand phenomena. Therefore, achieving a machine which is a paradigm for the quantum nature of a system is an engrossing challenge.… Read the rest
Gli argomenti di tesi sono di tipo teorico e riguardano il comportamento di sistemi fuori equilibrio. Una preparazione di base in meccanica statistica e’ essenziale. La conoscenza di un linguaggio di programmazione per lo sviluppo di codici di simulazione e’ auspicabile.
Il moto di una particella soggetta a forze aleatorie e’ descritto dalle leggi del moto browniano (diffusione).… Read the rest
In the context of wave propagation trough nonlinear media, the simplest form of control would be to devise a “wave diode” in which electromagnetic or elastic waves are transmitted differently along two opposite propagation directions.… Read the rest
Roberto Livi and Paolo Politi
Nonequilibrium Statistical Physics – A modern perspective
(Cambridge University Press, 2017)
Statistical mechanics has been proven to be successful at describing physical systems at thermodynamic equilibrium. Since most natural phenomena occur in nonequilibrium conditions, the present challenge is to find suitable physical approaches for such conditions: this book provides a pedagogical pathway that explores various perspectives.… Read the rest
Una ricerca, svolta in collaborazione fra fisici e chimici italiani, tedeschi e spagnoli, mostra che è possibile realizzare nano-sistemi ibridi depositando magneti molecolari su grafene. L’interazione fra gli spin dei magneti molecolari e il gas bidimensionale di elettroni del grafene modifica profondamente la dinamica quantistica degli spin molecolari. Ciò apre la strada al controllo dello spin mediante campi elettrici nei nano-dispositivi per la spintronica (elettronica di spin) basati sul grafene.… Read the rest
Serhiy Yanchuk and Giovanni Giacomelli published a topical review in Journal of Physics A: Mathematical and Theoretical.
Real-world systems can be strongly influenced by time delays occurring in self-coupling interactions, due to unavoidable finite signal propagation velocities. When the delays become significantly long, complicated high-dimensional phenomena appear and a simple extension of the methods employed in low-dimensional dynamical systems is not feasible.… Read the rest
Bruno Tiribilli 1, Giancarlo Margheri 1, Federica Pierucci 2 , Ambra Vestri 2, Elisabetta Meacci 2
1 Istituto dei Sistemi Complessi, del Consiglio Nazionale delle Ricerche, via Madonna del Piano 10, 50019, Sesto Fiorentino (FI).
2 Dipartimento di Scienze Biochimiche Sperimentali e Cliniche “Mario Serio”, Università di Firenze, Viale G B Morgagni 50, 50134 Firenze.
Scopo finale del progetto è l’applicazione della tecnica Surface Plasmon Resonance (SPR) alla rivelazione di un particolare nanoanticorpo, specifico per la sfingosina-1-fosfato (S1P), un importante agente in diverse vie metaboliche, ad esempio nel citoplasma cellulare, dove è stata dimostrata la sua funzione di regolazione dei flussi di ioni Ca2+.… Read the rest
Leonardo del Rosso 1,2, Milva Celli 1 & Lorenzo Ulivi
The properties of some forms of water ice reserve still intriguing surprises. Besides the several stable or metastable phases of pure ice, solid mixtures of water with gases are precursors of other ices, as in some cases they may be emptied, leaving a metastable hydrogen-bound water structure. We present here the first characterization of a new form of ice, obtained from the crystalline solid compound of water and molecular hydrogen called C0-structure filled ice.… Read the rest
LÉVY FLIGHT |
AVIAN
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EXPERIMENTS |
RESULTS |
THE TEAM |
LÉVY 2.0 |
Seabirds can fly for many days and nights across featureless oceans to their preferred feeding locations and then fly back to their nests without getting lost. How they do this has long been a mystery. Now through a careful analysis of their flight patterns, researchers have shown that seabirds are following their noses and navigate using an “odour map” – a mental patchwork picture of local odours.… Read the rest
Two researches of the ISC (Stefano Focardi and Sonia Lombardi), together with Federico Morimando (Studio Proeco) have visited dr. Atidzhe Ahmed and Prof. Peter Genov, colleagues at the Institute of biodiversity and ecosystems research of the Bulgarian academy of sciences (IBER-BAS). The aim of the trip was to design a new project on the movement ecology of the red deer (Cervus elaphus) in Bulgaria.… Read the rest
Massimiliano Papi and others published a scientific report on an antibacterial cloak produced by laser printing graphene oxide hydrogels mimicking the Cancer Pagurus carapace.… Read the rest
Soft condensed matter is characterized by gigantic responses to external perturbations which is the reason why these systems are extremely useful for applications, like liquid crystals in our cell phones displays. In contrast, hard condensed matter a.k.a. solids respond more weakly to external perturbations but present an enormous richness of interesting phases like metallic, insulating, magnetic, superconducting, ferroelectric, charge order, etc. … Read the rest
Nonlinear response in out-of-equilibrium systems can show counter-intuitive behaviors, for instance cases where the force increases but the response decreases (negative differential mobility). Sometimes the response crosses zero and changes sign with respect to the force (absolute negative mobility). In classical physics this is usually observed within complicate models with obstacles and traps. We have demonstrated such complex non-linear phenomena in a much simpler and realistic system, ie.… Read the rest
Convection in molecular fluids is provided by the competition between gravity and an adverse temperature gradient (two thermostats, the hotter below, the colder above). In a granular gas it can be achieved by a single thermostat at the base, for instance a vibrating piston. Energy dissipation provides the “second thermostat” which spontaneously forms gradient and may stabilize a convective state. Here we have demonstrated that even the simple dissipation in the collision between grains and lateral walls is sufficient to trigger convection, without any critical threshold.… Read the rest
Living matter at the microscale, many kinds of cells, bacteria and other organisms, self-propel through a viscous fluid which acts as a thermal bath, dissipating the energy provided by the internal motor (pseudopoda, flagella, etc.). This energetic balance is ruled by non-equilibrium thermodynamics, as for heat engines. In this theoretical work we have given a mesoscopic description of this process, which allows to measure a local heat dissipation and a local non-equilibrium temperature (associated to self-propulsion and to the forces driving the active particle) which together provide a definition of active entropy production which satisfies the Clausius inequality.… Read the rest
We have reproduced the self propulsion of bacteria and animals with 3d-printed “active granular particles”. Those small artificial insects walk on a rough vibrated plate because of a subtle interplay between material elastic properties and solid-on-solid friction. The advantage of 3d-printed objects is in the possibility to tune certain features (here the inclination of “legs”) in order to verify theoretical predictions and establish an optimal shape for running.… Read the rest
Caging is the typical microscopic phenomenon that “traps” molecules in a liquid at low temperature. The usual Brownian Motion of a tracer experiences a temporary “dynamical arrest” which eventually is broken restoring normal diffusion. In this work we have shown that at intermediate densities and temperature the same phenomenon occurs in granular liquids. At large densities and lower temperatures the late normal diffusion is replaced with superdiffusion.… Read the rest
Ionic liquids (IL) are salts formed by organic cations, like imidazolium, pyrrolidinium, ammonium or alkyl phosphonium, and organic/inorganic anions, like hexafluorophosphate, tetrafluoroborate, triflate, dicyanamide, tetracyanamethanide or bis(trifluoromethanesulfonyl)imide (TFSI). The presence of such bulky and asymmetric ions decreases the ion-ion interactions and lowers the melting point with respect to more classical salts, reaching values as low as -20°C.

ILs posses many peculiar properties, such as an extremely low vapor pressure, a high ionic conductivity, a high thermal, chemical and electrochemical stability, a high thermal capacity and a good solvent capability.… Read the rest
Hydrogen is attracting renewed interest as an energy carrier, due to the necessity of finding ecological energy media which may decrease the environmental pollution from fossil fuels. Hydrogen storage represents a nodal point for the development of a hydrogen economy.
Of the three possible ways to store hydrogen, i.e. as high pressure gas, as a liquid (~20 K at atmospheric pressure), or as hydrides in solids, the latter one appears as the most promising, due to the high mass and volume density and safety.… Read the rest
In all languages, rules have exceptions in the form of irregularities. Since rules make a language efficient, the persistence of irregularity is an anomaly. How language systems become rule governed, how and why they sustain exceptions to rules? Frequent words are unlikely to change over time (e.g., frequent verbs tend to maintain an irregular past tense form). What is the role of frequency in maintaining exceptions to rules?… Read the rest
Social networks have empirically been found to be assortative (i.e., the degree of neighboring nodes are positively correlated), while other networks (e.g., technological, biological) show the opposite pattern (disassortative). Why is that so?
How do these patterns change in signed networks, where relations indicate trust/distrust, friendship/enmity? Do individuals who dislike many others tend to dislike each other, or do they dislike those who dislike only very few others?… Read the rest
In the case of fast mutating viruses (e.g., Influenza virus), the virus-host interaction is driven by cross-immunity: after being infected by a strain, the host acquires immunity to a set of other strains antigenically similar to the infecting one (i.e., triggering the same host immune response). The evolutionary dynamics of viruses is therefore ruled by their relative antigenic distance. Can we understand the non trivial relation between antigenic and genetic distance?… Read the rest
The intermittent and self-similar fluctuations displayed by a slow crack during the propagation in a heterogeneous medium can be quantitatively described by an extension of a classical statistical model for fracture. The model yields the correct dynamical and morphological scaling, and allows to demonstrate that the scale invariance originates from the presence of a non-equilibrium, reversible, critical transition which, in the presence of dissipation, gives rise to self-organized critical behaviour.… Read the rest
Alberto Petri interviewed on “Rappresentanza o governabilità”, RAI ”Radio 3 Scienza”, February 3rd, 2014
… Read the restA Brownian Ratchet is a small engine which is conceived to extract work from molecular fluctuations. Examples of Brownian Ratchets occur in the cell, see for instance this nice movie about kinesin.
As well explained by Richard Feynmann, a Brownian Ratchet cannot perform its own task in an equilibrium environment, i.e. the fluctuations feeding energy to the ratchet cannot originate from a single thermal bath, in accordance with the second principle of thermodynamics.… Read the rest
A random laser is usually obtained pumping light through a disordered medium. The dynamics of light through a heterogeneous configuration of scatterers and cavities provides emitted spectra with random and fluctuating peaks which have a wide range of applications and are nowadays subject to an intense theoretical activity. In this work we have added a new flavour to the idea of random lasers, replacing the usually static disordered medium with a vibrofluidized granular material.… Read the rest
4000 spheres of steel (diameter 2mm) are deposited on a horizontal rough plate (200mm diameter, only a square 100mm X 100mm is shown) and are put in motion by vertical vibration of the plate (sinusoidal shaking, amplitude 0.7mm, frequency 200Hz). The resulting motion, on the plane, is a composition of random sliding on the plate and inelastic collisions among particles. This is a “non-equilibrium” Brownian motion.… Read the rest
The term “soft matter” refers to a very large class of materials, whose common characteristic is that they are composed of mesoscopic particles, i.e. particles with typical sizes ranging from 1 nm to a few microns. These particles are normally dispersed in a solvent, whose molecules are much smaller in size (typically of atomic dimensions). In addition, the solution may contain other small objects, such as polymeric chains, salt ions, etc.… Read the rest
Crystalline Ce has a remarkable phase diagram in that is the solid state analogue of a Van der Walls system with a line of discontinuous transitions ending at a critical point.
The two phases alpha and gamma have the same cubic symmetry and differ only on density just like water and vapor but in the solid state!.
However unlike water and vapor the critical exponents close to the critical point are not three dimensional Ising critical exponents, as one would naively guess from symmetries, but classical (Gaussian) exponents.… Read the rest
Since July 2010, the Granular Dynamics Laboratory is operative – originally in room “010” and (from november 2012) – in room “012” (ground floor of Fermi Building of the Physics Department) at the Sapienza unit of ISC. The laboratory includes two main experimental setups:
Steel spheres move on a plate. The “thermostat ” is a vibrating wall, following a sine law with frequency 20 Hz . Weak gravity (the plate has a small angle of inclination) draws the spheres toward the vibrating wall. In 5 minutes, slowly increasing the amplitude, the many “phases” of a granular material are explored, from an almost perfect crystal, through several liquid/turbulent/convective regimes, up to a gas-solid coexistence.… Read the rest
Synchronization is a long known phenomenon dating back to Huygens experiments who observed that suspending two pendula “…in the same wooden beam, the motions of each pendulum in opposite swings were so much in agreement that they never receded the least bit from each other and the sound of each was always heard simultaneously“. In spite of the early discovery, the phenomenon was fully understood much later with the experiments and theoretical analysis of E.… Read the rest
| Founding Body: | MIUR, Italy (reserved to selected ERC-Starting Grants 2007) |
|---|---|
| Total grant: | € 1200k |
| Principal Investigator: | Andrea Puglisi |
| Other participants: | |
| Project duration: | 2009-2014 |
| Website: |
In recent years it has become widely recognized that many large-scale phenomena observed in social systems are the “macroscopic” complex effect of the “microscopic” simple behavior of a large number of interacting agents. This has led social scientists to the introduction of elementary models of social behavior (cellular automata, agent-based models). Many of these models are somehow relatives of models that have been introduced in modern traditional statistical physics, and it is natural to approach them using the same concepts and tools that have been successfully applied in physics.… Read the rest
In social phenomena every individual interacts with a limited number of peers, usually negligible as compared with the total number of people in the system. In spite of that, human societies are characterized by stunning global regularities. There are transitions from disorder to order, like the spontaneous emergence of a common language/culture or the creation of consensus about a specific topic.… Read the rest
There exists an overwhelming diversity of landscapes on Earth. A cornerstone of modern geomorphology came with the realization that all the different features of the terrestrial surface result from the accumulated effect of current geological agents [Lyell, 1830]. This principle established for the first time a qualitative relationship between pattern and process in geology.
More than one century later, fractal geometry gave a theoretical framework able to provide quantitative measures for the patterns of landscapes, which were identified in a first approximation as self-similar, and triggered the research on mechanistic and theoretical models to identify the underlying constructive rules responsible for their appearance.… Read the rest
In system with strong electron-phonon interaction, the carriers loose mobility, ultimately acquiring polaronic character. A polaron is a state in which the phonon and electron degrees of freedom are strongly entangled, and the presence of an electron is associated to a finite lattice distortion, which in turn bind
Phonon distribution function P(n) and magnetic polaron size Lp as function of the exchange coupling J, signalizing the formation of the spin/lattice polaron
s the electron leading to the so-called self-trapping effect.… Read the rest
Even before the identification of galaxies as stellar systems, astronomers have classified them based on their visual appearance. Galaxies in the local universe can organized in a sequence of morphologies (e.g. the Hubble sequence) which must be the result of the specific processes that originated them.
The relative roles over cosmic time of processes such as the merging of dark matter haloes, dissipation, starburst, feedback, active galactic nuclei (AGN) activity, etc.,… Read the rest
A globular cluster (GC) is a spherical collection of stars that orbits a galactic core as a satellite.
Globular clusters are very tightly bound by gravity, which gives them their spherical shapes and relatively high stellar densities toward their centers. The name of this category of star cluster is derived from the Latin globulus—a small sphere. Globular clusters are fairly common; there are about 158 currently known globular clusters in the Milky Way, with perhaps 10–20 more undiscovered.… Read the rest
The wide applicability of the random walks (RW) to natural phenomena relies just on the possibility to introduce appropriate generalizations on the probabilistic nature of displacements. A straightforward generalization is realized by assuming correlations in displacements to obtain the so called correlated random walks (CRW).
This possibility extends also to a set of particles distributed in space leading to the definition of spatially correlated random walks.… Read the rest
How do properties of molecular trajectories reflect on large scale transport and relaxation properties? Is it possible to directly and experimentally verify the Boltzmann’s program, connecting the microscopic level to the macroscopic description? Can we zoom into an out-of-equilibrium fluid and reveal, in the laboratory, its underlying microscopic reversibility? These are some of the questions addressed by the GRANULARCHAOS project, funded by an IDEAS grant (originally selected by ERC and then funded by italian FIRB) for five years.… Read the rest
A System with long-range interactions is characterized by an inter-particle potential which decays at large distances with a power law exponent which is smaller than the dimension of the embedding space. Classical examples include for instance: self-gravitating systems, unscreened Coulomb systems, ion beams, wave-particle systems of relevance to plasma physics and others.
The behaviour of the above mentioned systems is interesting both from the point of view of stable (or metastable) states, because equilibrium statistical mechanics shows new types of phase transitions and cases of ensemble inequivalence, and from the dynamical point of view, because they display peculiar fast relaxation followed by the formation of quasi-stationary states that are related to the underlying Vlasov-like equation.… Read the rest
The most prominent feature of the initial conditions of the matter spatial distribution in the early universe, in standard theoretical models, derived from inflationary mechanisms, is that matter density field presents on large scale super-homogeneous features. This means the following. If one considers the paradigm of uniform distributions, the Poisson process where particles are placed completely randomly in space, the mass fluctuations in a sphere of radius R growths as the volume of the sphere.… Read the rest
In equilibrium statistical mechanics the distinction between short and long range interactions is given by the integrability or not of the pair potential. However for what concerns only the clustering dynamics of a particle distribution under the effect of an attractive pair interaction, it seems by recent works that the distinction is given by the integrability of the pair force instead of the potential.… Read the rest
The investigation of the electronic properties of graphene (single hexagonal layer of carbon atoms) has attracted a renewed interest after the development of recent techniques which permit to produce and manage single-layer (and also multilayer) samples of this materials. Nowadays truly atomic single-layer isolated samples are available as well as epitaxially grown graphene on substrates.
A large interest, for its potential technological applications, concerns the investigation of optical and transport properties of both single-layer and multi-layered graphene, which are dominated by its so-called relativistic Dirac-like electronic structure (see Figure on the right).
The discovery that simple deterministic nonlinear systems could display dynamical evolution characterized by a randomness similar to stochastic processes changed very much researchers’ attitude toward determinism and predictability of natural phenomena. Determinstic chaos has been successfully invoked to interpret several irregular behaviors, however its role to the fundaments of statistical physics still remains debated in modern statistical mechanics. In other terms, one is tempted to think that a macroscopic system with chaotic microscopic interactions is more robust with respect to statistical mechanical principles thant the same system with non-chaotic interactions.… Read the rest
In hard magnetic materials, the domain walls movement or even creation is suppressed, and other mechanisms, like domains nucleation and coherent spin rotation enter in the process of magnetization reversal. For these kind of materials a description in terms of spin models is more appropriate. We focused on the non-equilibrium properties of the random field Ising model (RFIM), to describe the competition between quenched disorder and exchange interactions and their effect on the hysteretic behavior.… Read the rest
Problems susceptible to be mathematically represented by stochastic Langevin equations including a multiplicative noise abound not only in physics, but also in biology, ecology, economy, or social sciences. In a broad sense a Langevin equation is said to be multiplicative if the noise amplitude depends on the state variables themselves. In this sense, problems exhibiting absorbing states, i.e. fluctuation-less states in which the system can be trapped, are described by equations whose noise amplitude is proportional to the square-root of the (space and time dependent) activity density, vanishing at the absorbing state.… Read the rest
In January 2008 a new family of superconductors has been discovered with FeAs layers. Iron is a magnetic ion and in traditional superconductors small amounts of magnetic impurities kill superconductivity so an iron based superconductor is at first sight surprising.
Tc has grow rapidly beyond 50K opening a new gate to high-Tc superconductivity. In addition the phase diagram has some similarities with the cuprates which suggest that understanding the superconductors from this new iron age can help to solve the mistery of the supercundoctors from the copper age.… Read the rest
Both the static and the dynamical behaviour occurring in mean field spin glass models models can be interpreted as consequences of the complex (free) energy landscape that spin glasses have, with many minima, valleys and saddles. Traditionally, much attention has been devoted in the past to the analysis of absolute minima, i.e. equilibrium states. More recently, we have understood that also metastable states, i.e.… Read the rest
Many features predicted by mean field spin glass models, such as the behaviour of susceptibilities and correlation functions or the occurrence of aging and off-equilibrium dynamics, are qualitatively observed in experiments, suggesting that the mean field scenario may hold for finite dimensional systems also. To investigate this hypothesis a field theory for the fluctuations around the mean field solution has been developed.… Read the rest
A large variety of systems with competing short and long range interactions self-organizes in domain patterns as reviewed by Seul and Andelman. Examples range from magnetic systems (left figure A) to organic systems (left figure B).
Inhomogeneous states display a simple set of predominant morphologies like circular droplets and stripes in two-dimensional (2D) systems, and layers, cylindrical rods and spherical droplets in three-dimensional (3D) systems.… Read the rest
Close to the glass transition supercooled liquids display an impressive increase of the relaxation time, without any clear sign of growing thermodynamic order, nor correlation length. This is at variance with physical intuition, which suggests that a large relaxation time is always associated to a large correlation length. Even though dynamical length scales were introduced and measured, nothing similar was thought to be possible for thermodynamic lengths.… Read the rest
Organic field effect transistors (OFETs) are providing exciting prospects for potential applications in electronics. The active elements of these devices use “plastic” semiconductors, based on carbon and hydrogen. Among the advantages compared to classical silicon transistors, this new generation of components should combine mechanical flexibility, low weight, transparency and low cost. Enormous progress has been made to improve the performance of these devices through optimising the synthesis processes, drastically reducing the concentration of impurities present.… Read the rest
The term “crackling noise” refers to the signal that some disordered systems produce as a response to an external driving field smoothly changing in time. Due to the presence of disorder, crackling signals are extremely irregular, despite the steady increase of the external forcing. They are typically characterized by a sequence of pulses of very different sizes and durations, separated by quiescence intervals.… Read the rest
The physics of thin and ultra-thin magnetic films has been extensively studied in the recent past, because of its important implications for applications to high frequency devices. Power losses in ferromagnetic materials generally depend on the frequency of the applied field, a phenomenon referred to as dynamic hysteresis. The problem has great importance from a purely theoretical point of view, for the understanding of the dynamics of disordered magnetic systems, which represents a central issue in non–equilibrium statistical mechanics.… Read the rest
During the last decade it has become clear that the topology in many systems, ranging from technological to social to biological, is not well described by regular lattices nor by random graphs. Complex networks, characterized by small-world effects, large connectivity fluctuations, clustering, correlations and other nontrivial features are often a better description of many natural and man-made systems. Since many of such networks describe the topological patterns that mediate various sorts of interactions among nodes, it is natural and interesting to wonder what is the effect of complex topologies on dynamical processes taking place on them.… Read the rest
Until now, the study of human dynamics has been done only qualitatively. Actually, the present possibility to have quantitative data on the kind and nature of social relationships through social networks is driving a rapid change in the field. Thanks to the emergence of detailed datasets that capture human behavior, we can now follow specific human actions in ultimate detail. One of the first measurable quantity with which one can describe the relationship between humans is the timing and order with which we perform specific tasks.… Read the rest
The relevance of antisymmetric superexchange interactions in spin Hamiltonians describing quantum antiferromagnetic (AF) systems has been acknowledged long ago by Dzyaloshinskii. Soon after, Moriya showed that such interactions arise naturally in perturbation theory due to the spin-orbit coupling in magnetic systems with low symmetry. Nowadays, a number of AF systems are known to belong to the class of Dzyaloshinskii-Moriya (DM) magnets, such as ?-Fe… Read the rest
In a nutshell, a random laser is the coherent emission from active stochastic resonators.
In a series of articles around 1966, a Russian scientist V. S. Letokhov, of the Lebedev Physics Institute in Dubna considered the generation of light in the interstellar medium. In the presence of scatterers, as for example dust particles, photons diffuse like neutrons and, if some mechanism (following Letokhov a “negative absorption”) is able to increase their number, a sort of photonic reactor can be realized.… Read the rest
In conventional superconductors, the repulsive interaction between electrons opposes to phonon-mediated pairing. We have shown that even phonon-mediated superconductivity can be favoured by repulsion under suitable conditions which are realized in fullerenes.
Trivalent alkali-doped fullerenes are almost certainly electron-phonon superconductors, and their critical temperature can reach around 40K. There are however many experimental evidences that seem to exclude a simple BCS (or Migdal-Eliashberg) scenario, since electron-electron correlations are likely to play a central role.… Read the rest
Spin Glasses are dilute magnetic alloys where the interactions between spins are randomly ferromagnetic or anti-ferromagnetic, and are considered as paradigmatic examples of frozen disorder. The presence of disorder (the random interactions) induces frustration and a greater difficulty for the system to find optimal configurations. As a consequence, these systems exhibit non trivial thermodynamic and dynamic properties, different and richer than those observed in their non disordered counterpart.… Read the rest
Collective phenomena in economics, social sciences and ecology are very attractive for statistical physicists, especially in view of the empirical abundance of non-trivial fluctuation patterns and statistical regularities — think of returns in financial markets or of allometric scaling in ecosystems — which pose intriguing theoretical challenges. On an abstract level, the problems at stake are indeed not too different from, say, understanding how spontaneous magnetization may arise in a magnetic system, since what one wants in both cases is to understand how the effects of interactions at the microscopic scale can build up to the macroscopic scale.… Read the rest
One of the new frontiers in condensed matter physics is development and engineering of electronic devices which carrier “bit” informations in the spin degree of freedom of the electronc instead of their charge. This research line is called indeed “spintronics”. Within this context the spin-or
Rashba band-spilling and spin ordering: from J. Sinova et al., Phys. Rev. Lett. 92, 126603 (2004).
If the mechanism of high-Tc superconductivity is electronic, to understand the electronic excitation spectrum is as important as to understand phonons was important to develop BCS theory. In this regard charge and spin inhomogeneous states, often found in strongly correlated systems, are interesting because they can support new collective modes, “electronic phonons”, that would not be present in a weakly interacting fluid.… Read the rest
The conventional understanding of the electron-phonon phenomenology in condensed matter strongly relies on the adiabatic assumption, i.e. that nuclei dynamics is much slower than the electron one. In solid crystals the validity of this assumption is usually related to the comparison of the phonon frequencies with the Fermi energy EF. In conventional systems , assuring thus the reliability of the adiabatic assumption.… Read the rest
Basically all existing models of collective animal behaviour (bird flocks, fish schools, etc) assume that the interaction between different individuals depends on the metric distance, just as in physics. This implies, for example, that two birds 5 meters apart interact more strongly than two birds 10 meters apart.
Models developed by biologists are based on a “behavioural zones” scheme, where each zone is associated to one of the three basic ingredients of all models: short range repulsion, alignment, long range attraction.… Read the rest
Protein Folding is a specific chemical and physical transition by which a linear sequence of aminoacids finds its functional (native) three dimensional structure. The theoretical study of protein folding represents perhaps one of the most challenging research with a marked interdisciplinary character, where biology, chemistry, physics, mathematics and computer science can fruitfully interact each other.
Our activity in this field concerns the prediction of folding mechanisms by the knowledge of tertiary structure only.
Education:
Post-Doc, Theoretical Physics, Physics Dept, Manchester University, UK, 2001 (with Alan Bray and Mike Moore)
Post-Doc, Condensed Matter, Theoretical Physics Dept, Oxford University, UK, 1999 (with David Sherrington)
Ph.D. in Theoretical Physics, University of Rome Sapienza, Italy, 1998 (Spin-Glasses – advisor Giorgio Parisi)
M.S. and B.A. in Theoretical Physics, University of Milan and SISSA – Trieste, Italy, 1995 (Conformal Field Theory – advisor Giuseppe Mussardo)
I was trained as a theoretical physicist and I have studied for some years the statistical mechanics of disordered systems, with a particular interest in spin-glasses, structural glasses and supercooled liquids. … Read the rest
Scale-Free Networks are present in a wide list of phenomena. Examples range from the structure of the Internet and that of the WWW (we shall see in the following that they are different systems) to the interconnections between financial agents or species predation in ecological food webs. Thanks to the simplicity of graph theory it is very easy to provide a network description for different systems.… Read the rest
When a binary fluid mixture at the critical concentration is cooled from a high temperature to a sufficiently low temperature (below a critical one), the original homogeneous phase becomes unstable and spontaneously evolves into two phases separated by an interface. As time advances, an out-of-equilibrium process of phase ordering takes place through the formation of domains of a single phase that grows algebraically in time as L(t)~t1/3.… Read the rest
Recently, part of the research activity on turbulence has focused on temporal properties of turbulent statistics which are much less known than the equivalent spatial properties, and are expected to bring information on some of the mechanisms responsible for intermittency in turbulence, for example lagrangian motion is strongly affected by the presence of vortical motion around vortex filaments (see Figure 1).… Read the rest
The ability of efficiently mixing transported substances is one of the most distinctive properties of turbulence. For instance, it is turbulence (induced by the spoon) that allows cream to rapidly invade a cup of coffee, indeed if only molecular diffusion would be at play in the coffee at rest the same process would require many hours! Given the statistical complexity of a turbulent velocity field, it is natural to wonder about the resulting complexity in the statistical features of the transported concentration field of a substance (e.g.… Read the rest
We already mentioned that enhanced mixing is probably one of the most distinguishing feature of turbulence. When a turbulent flow is seeded with particulate matter having a finite size and/or density different from that of the carrier fluid, new features appear. The figure on the left show the instantaneous position particles which are heavier (e.g. water drops in air) resp. lighter (e.g.… Read the rest
