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Schirmacher W, Paoluzzi M, Mocanu FC, Khomenko D, Szamel G, Zamponi F, Ruocco G. The nature of non-phononic excitations in disordered systems. Nat Commun 2024; 15:3107. [PMID: 38600083 DOI: 10.1038/s41467-024-46981-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2023] [Accepted: 03/18/2024] [Indexed: 04/12/2024] Open
Abstract
The frequency scaling exponent of low-frequency excitations in microscopically small glasses, which do not allow for the existence of waves (phonons), has been in the focus of the recent literature. The density of states g(ω) of these modes obeys an ωs scaling, where the exponent s, ranging between 2 and 5, depends on the quenching protocol. The orgin of these findings remains controversal. Here we show, using heterogeneous-elasticity theory, that in a marginally-stable glass sample g(ω) follows a Debye-like scaling (s = 2), and the associated excitations (type-I) are of random-matrix type. Further, using a generalisation of the theory, we demonstrate that in more stable samples, other, (type-II) excitations prevail, which are non-irrotational oscillations, associated with local frozen-in stresses. The corresponding frequency scaling exponent s is governed by the statistics of small values of the stresses and, therefore, depends on the details of the interaction potential.
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Affiliation(s)
- Walter Schirmacher
- Institut für Physik, Staudinger Weg 7, Universität Mainz, D-55099, Mainz, Germany.
- Center for Life Nano Science @Sapienza, Istituto Italiano di Tecnologia, 291 Viale Regina Elena, I-00161, Roma, Italy.
| | - Matteo Paoluzzi
- Istituto per le Applicazioni del Calcolo del Consiglio Nazionale delle Ricerche, Via Pietro Castellino 111, 80131, Napoli, NA, Italy
- Departament de Física de la Matèria Condensada, Universitat de Barcelona, Carrer de Martí i Franquès 1, 08028, Barcelona, Spain
- Dipartimento di Fisica, Universita' di Roma "La Sapienza", P'le Aldo Moro 5, I-00185, Roma, Italy
| | - Felix Cosmin Mocanu
- Dept. of Materials, Univ. of Oxford, Parks Road, Oxford, OX13PH, UK
- Laboratoire de Physique de l'Ecole Normale Supérieure, ENS, Université PSL, CNRS, Sorbonne Université, Université Paris-Diderot, Sorbonne Paris Cité, Paris, France
| | - Dmytro Khomenko
- Dipartimento di Fisica, Universita' di Roma "La Sapienza", P'le Aldo Moro 5, I-00185, Roma, Italy
| | - Grzegorz Szamel
- Dept. of Chemistry, Colorado State University, Fort Collins, CO, 80523, USA
| | - Francesco Zamponi
- Dipartimento di Fisica, Universita' di Roma "La Sapienza", P'le Aldo Moro 5, I-00185, Roma, Italy
- Laboratoire de Physique de l'Ecole Normale Supérieure, ENS, Université PSL, CNRS, Sorbonne Université, Université Paris-Diderot, Sorbonne Paris Cité, Paris, France
| | - Giancarlo Ruocco
- Center for Life Nano Science @Sapienza, Istituto Italiano di Tecnologia, 291 Viale Regina Elena, I-00161, Roma, Italy.
- Dipartimento di Fisica, Universita' di Roma "La Sapienza", P'le Aldo Moro 5, I-00185, Roma, Italy.
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2
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Miotto M, Rosito M, Paoluzzi M, de Turris V, Folli V, Leonetti M, Ruocco G, Rosa A, Gosti G. Collective behavior and self-organization in neural rosette morphogenesis. Front Cell Dev Biol 2023; 11:1134091. [PMID: 37635866 PMCID: PMC10448396 DOI: 10.3389/fcell.2023.1134091] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2022] [Accepted: 07/26/2023] [Indexed: 08/29/2023] Open
Abstract
Neural rosettes develop from the self-organization of differentiating human pluripotent stem cells. This process mimics the emergence of the embryonic central nervous system primordium, i.e., the neural tube, whose formation is under close investigation as errors during such process result in severe diseases like spina bifida and anencephaly. While neural tube formation is recognized as an example of self-organization, we still do not understand the fundamental mechanisms guiding the process. Here, we discuss the different theoretical frameworks that have been proposed to explain self-organization in morphogenesis. We show that an explanation based exclusively on stem cell differentiation cannot describe the emergence of spatial organization, and an explanation based on patterning models cannot explain how different groups of cells can collectively migrate and produce the mechanical transformations required to generate the neural tube. We conclude that neural rosette development is a relevant experimental 2D in-vitro model of morphogenesis because it is a multi-scale self-organization process that involves both cell differentiation and tissue development. Ultimately, to understand rosette formation, we first need to fully understand the complex interplay between growth, migration, cytoarchitecture organization, and cell type evolution.
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Affiliation(s)
- Mattia Miotto
- Center for Life Nano and Neuro Science, Istituto Italiano di Tecnologia, Rome, Italy
- Department of Physics, Sapienza University of Rome, Rome, Italy
| | - Maria Rosito
- Center for Life Nano and Neuro Science, Istituto Italiano di Tecnologia, Rome, Italy
- Department of Physiology and Pharmacology V. Erspamer, Sapienza University of Rome, Rome, Italy
| | - Matteo Paoluzzi
- Departament de Física de la Matèria Condensada, Universitat de Barcelona, Barcelona, Spain
| | - Valeria de Turris
- Center for Life Nano and Neuro Science, Istituto Italiano di Tecnologia, Rome, Italy
| | - Viola Folli
- Center for Life Nano and Neuro Science, Istituto Italiano di Tecnologia, Rome, Italy
- D-TAILS srl, Rome, Italy
| | - Marco Leonetti
- Center for Life Nano and Neuro Science, Istituto Italiano di Tecnologia, Rome, Italy
- D-TAILS srl, Rome, Italy
- Soft and Living Matter Laboratory, Institute of Nanotechnology, Consiglio Nazionale delle Ricerche, Rome, Italy
| | - Giancarlo Ruocco
- Center for Life Nano and Neuro Science, Istituto Italiano di Tecnologia, Rome, Italy
- Department of Physics, Sapienza University of Rome, Rome, Italy
| | - Alessandro Rosa
- Center for Life Nano and Neuro Science, Istituto Italiano di Tecnologia, Rome, Italy
- Department of Biology and Biotechnologies Charles Darwin, Sapienza University of Rome, Rome, Italy
| | - Giorgio Gosti
- Center for Life Nano and Neuro Science, Istituto Italiano di Tecnologia, Rome, Italy
- Soft and Living Matter Laboratory, Institute of Nanotechnology, Consiglio Nazionale delle Ricerche, Rome, Italy
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3
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Pellicciotta N, Paoluzzi M, Buonomo D, Frangipane G, Angelani L, Di Leonardo R. Colloidal transport by light induced gradients of active pressure. Nat Commun 2023; 14:4191. [PMID: 37443155 DOI: 10.1038/s41467-023-39974-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2022] [Accepted: 07/06/2023] [Indexed: 07/15/2023] Open
Abstract
Active fluids, like all other fluids, exert mechanical pressure on confining walls. Unlike equilibrium, this pressure is generally not a function of the fluid state in the bulk and displays some peculiar properties. For example, when activity is not uniform, fluid regions with different activity may exert different pressures on the container walls but they can coexist side by side in mechanical equilibrium. Here we show that by spatially modulating bacterial motility with light, we can generate active pressure gradients capable of transporting passive probe particles in controlled directions. Although bacteria swim faster in the brighter side, we find that bacteria in the dark side apply a stronger pressure resulting in a net drift motion that points away from the low activity region. Using a combination of experiments and numerical simulations, we show that this drift originates mainly from an interaction pressure term that builds up due to the compression exerted by a layer of polarized cells surrounding the slow region. In addition to providing new insights into the generalization of pressure for interacting systems with non-uniform activity, our results demonstrate the possibility of exploiting active pressure for the controlled transport of microscopic objects.
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Affiliation(s)
- Nicola Pellicciotta
- Dipartimento di Fisica, Sapienza Università di Roma, Piazzale A. Moro 5, 00185, Roma, Italy.
- NANOTEC-CNR, Soft and Living Matter Laboratory, Institute of Nanotechnology, Piazzale A. Moro 5, 00185, Roma, Italy.
| | - Matteo Paoluzzi
- Departament de Física de la Matèria Condensada, Universitat de Barcelona, C. Martí Franquès 1, 08028, Barcelona, Spain
| | - Dario Buonomo
- Dipartimento di Fisica, Sapienza Università di Roma, Piazzale A. Moro 5, 00185, Roma, Italy
| | - Giacomo Frangipane
- Dipartimento di Fisica, Sapienza Università di Roma, Piazzale A. Moro 5, 00185, Roma, Italy
- NANOTEC-CNR, Soft and Living Matter Laboratory, Institute of Nanotechnology, Piazzale A. Moro 5, 00185, Roma, Italy
| | - Luca Angelani
- Dipartimento di Fisica, Sapienza Università di Roma, Piazzale A. Moro 5, 00185, Roma, Italy
- ISC-CNR, Institute for Complex Systems, Piazzale A. Moro 5, 00185, Roma, Italy
| | - Roberto Di Leonardo
- Dipartimento di Fisica, Sapienza Università di Roma, Piazzale A. Moro 5, 00185, Roma, Italy.
- NANOTEC-CNR, Soft and Living Matter Laboratory, Institute of Nanotechnology, Piazzale A. Moro 5, 00185, Roma, Italy.
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Abstract
Using the path integral representation of the nonequilibrium dynamics, we compute the most probable path between arbitrary starting and final points that is followed by an active particle driven by persistent noise. We focus our attention on the case of active particles immersed in harmonic potentials, where the trajectory can be computed analytically. Once we consider the extended Markovian dynamics where the self-propulsive drive evolves according to an Ornstein-Uhlenbeck process, we can compute the trajectory analytically with arbitrary conditions on position and self-propulsion velocity. We test the analytical predictions against numerical simulations and we compare the analytical results with those obtained within approximated equilibriumlike dynamics.
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Affiliation(s)
- Andrea Crisanti
- Dipartimento di Fisica, Sapienza Università di Roma Piazzale A. Moro 2, I-00185 Rome, Italy
| | - Matteo Paoluzzi
- Departament de Física de la Matèria Condensada, Universitat de Barcelona, C. Martí Franquès 1, 08028 Barcelona, Spain
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5
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Abstract
In active φ^{4} field theories the nonequilibrium terms play an important role in describing active phase separation; however, they are irrelevant, in the renormalization group sense, at the critical point. Their irrelevance makes the critical exponents the same as those of the Ising universality class. Despite their irrelevance, they contribute to a nontrivial scaling of the entropy production rate at criticality. We consider the nonequilibrium dynamics of a nonconserved scalar field φ (Model A) driven out-of-equilibrium by a persistent noise that is correlated on a finite timescale τ, as in the case of active baths. We perform the computation of the density of entropy production rate σ and we study its scaling near the critical point. We find that similar to the case of active Model A, and although the nonlinearities responsible for nonvanishing entropy production rates in the two models are quite different, the irrelevant parameter τ makes the critical dynamics irreversible.
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Affiliation(s)
- Matteo Paoluzzi
- Departament de Física de la Matèria Condensada, Universitat de Barcelona, Carrer Martí i Franquès 1, 08028 Barcelona, Spain
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Paoluzzi M, Gnan N, Grassi F, Salvetti M, Vanacore N, Crisanti A. A single-agent extension of the SIR model describes the impact of mobility restrictions on the COVID-19 epidemic. Sci Rep 2021; 11:24467. [PMID: 34963680 PMCID: PMC8714823 DOI: 10.1038/s41598-021-03721-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2021] [Accepted: 12/07/2021] [Indexed: 12/04/2022] Open
Abstract
Mobility restrictions are successfully used to contain the diffusion of epidemics. In this work we explore their effect on the epidemic growth by investigating an extension of the Susceptible-Infected-Removed (SIR) model in which individual mobility is taken into account. In the model individual agents move on a chessboard with a Lévy walk and, within each square, epidemic spreading follows the standard SIR model. These simple rules allow to reproduce the sub-exponential growth of the epidemic evolution observed during the Covid-19 epidemic waves in several countries and which cannot be captured by the standard SIR model. We show that we can tune the slowing-down of the epidemic spreading by changing the dynamics of the agents from Lévy to Brownian and we investigate how the interplay among different containment strategies mitigate the epidemic spreading. Finally we demonstrate that we can reproduce the epidemic evolution of the first and second COVID-19 waves in Italy using only 3 parameters, i.e , the infection rate, the removing rate, and the mobility in the country. We provide an estimate of the peak reduction due to imposed mobility restrictions, i. e., the so-called flattening the curve effect. Although based on few ingredients, the model captures the kinetic of the epidemic waves, returning mobility values that are consistent with a lock-down intervention during the first wave and milder limitations, associated to a weaker peak reduction, during the second wave.
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Affiliation(s)
- Matteo Paoluzzi
- Departament de Física de la Matèria Condensada, Universitat de Barcelona, C. Martí Franquès 1, 08028, Barcelona, Spain.
| | - Nicoletta Gnan
- CNR-ISC, Institute for Complex Systems UOS "Sapienza", Piazzale A. Moro 2, 00185, Rome, Italy
- Department of Physics, Sapienza University of Rome, Rome, Italy
| | - Francesca Grassi
- Department of Physiology and Pharmacology, Sapienza University of Rome, Rome, Italy
| | - Marco Salvetti
- Department of Neurosciences, Mental Health and Sensory Organs, Sapienza University of Rome, Rome, Italy
- IRCCS Istituto Neurologico Mediterraneo Neuromed, Pozzilli, Italy
| | - Nicola Vanacore
- National Center for Disease Prevention and Health Promotion, Istituto Superiore di Sanità, Rome, Italy
| | - Andrea Crisanti
- CNR-ISC, Institute for Complex Systems UOS "Sapienza", Piazzale A. Moro 2, 00185, Rome, Italy
- Department of Physics, Sapienza University of Rome, Rome, Italy
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7
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Paoluzzi M, Angelani L, Gosti G, Marchetti MC, Pagonabarraga I, Ruocco G. Alignment interactions drive structural transitions in biological tissues. Phys Rev E 2021; 104:044606. [PMID: 34781522 DOI: 10.1103/physreve.104.044606] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2021] [Accepted: 09/23/2021] [Indexed: 12/24/2022]
Abstract
Experimental evidence shows that there is a feedback between cell shape and cell motion. How this feedback impacts the collective behavior of dense cell monolayers remains an open question. We investigate the effect of a feedback that tends to align the cell crawling direction with cell elongation in a biological tissue model. We find that the alignment interaction promotes nematic patterns in the fluid phase that eventually undergo a nonequilibrium phase transition into a quasihexagonal solid. Meanwhile, highly asymmetric cells do not undergo the liquid-to-solid transition for any value of the alignment coupling. In this regime, the dynamics of cell centers and shape fluctuation show features typical of glassy systems.
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Affiliation(s)
- Matteo Paoluzzi
- Departament de Física de la Matèria Condensada, Universitat de Barcelona, C. Martí Franquès 1, 08028 Barcelona, Spain
| | - Luca Angelani
- ISC-CNR, Institute for Complex Systems, Piazzale A. Moro 2, I-00185 Rome, Italy.,Dipartimento di Fisica, Sapienza Università di Roma Piazzale A. Moro 2, I-00185 Rome, Italy
| | - Giorgio Gosti
- Center for Life Nano Science, Istituto Italiano di Tecnologia, Viale Regina Elena 291, I-00161 Rome, Italy
| | - M Cristina Marchetti
- Department of Physics, University of California Santa Barbara, Santa Barbara, California 93106, USA
| | - Ignacio Pagonabarraga
- Departament de Física de la Matèria Condensada, Universitat de Barcelona, C. Martí Franquès 1, 08028 Barcelona, Spain.,CECAM Centre Européen de Calcul Atomique et Moléculaire, École Polytechnique Fédérale de Lausanne (EPFL), Batochime, Avenue Forel 2, 1015 Lausanne, Switzerland.,UBICS University of Barcelona Institute of Complex Systems, Martí i Franquès 1, 08028 Barcelona, Spain
| | - Giancarlo Ruocco
- Dipartimento di Fisica, Sapienza Università di Roma Piazzale A. Moro 2, I-00185 Rome, Italy.,Center for Life Nano Science, Istituto Italiano di Tecnologia, Viale Regina Elena 291, I-00161 Rome, Italy
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8
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Maggi C, Paoluzzi M, Crisanti A, Zaccarelli E, Gnan N. Universality class of the motility-induced critical point in large scale off-lattice simulations of active particles. Soft Matter 2021; 17:3807-3812. [PMID: 33645615 DOI: 10.1039/d0sm02162h] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
We perform large-scale computer simulations of an off-lattice two-dimensional model of active particles undergoing a motility-induced phase separation (MIPS) to investigate the system's critical behaviour close to the critical point of the MIPS curve. By sampling steady-state configurations for large system sizes and performing finite size scaling analysis we provide exhaustive evidence that the critical behaviour of this active system belongs to the Ising universality class. In addition to the scaling observables that are also typical of passive systems, we study the critical behaviour of the kinetic temperature difference between the two active phases. This quantity, which is always zero in equilibrium, displays instead a critical behavior in the active system which is well described by the same exponent of the order parameter in agreement with mean-field theory.
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Affiliation(s)
- Claudio Maggi
- NANOTEC-CNR, Institute of Nanotechnology, Soft and Living Matter Laboratory -Piazzale A. Moro 2, I-00185, Roma, Italy. and Dipartimento di Fisica, Università di Roma "Sapienza", I-00185, Roma, Italy
| | - Matteo Paoluzzi
- Departamento de Fìsica de la Matèria Condensada, Universitat de Barcelona, C. MartìFranquès 1, 08028 Barcelona, Spain
| | - Andrea Crisanti
- Dipartimento di Fisica, Università di Roma "Sapienza", I-00185, Roma, Italy and CNR-ISC, Institute of Complex Systems, Roma, Italy.
| | - Emanuela Zaccarelli
- Dipartimento di Fisica, Università di Roma "Sapienza", I-00185, Roma, Italy and CNR-ISC, Institute of Complex Systems, Roma, Italy.
| | - Nicoletta Gnan
- Dipartimento di Fisica, Università di Roma "Sapienza", I-00185, Roma, Italy and CNR-ISC, Institute of Complex Systems, Roma, Italy.
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9
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Li YW, Wei LLY, Paoluzzi M, Ciamarra MP. Softness, anomalous dynamics, and fractal-like energy landscape in model cell tissues. Phys Rev E 2021; 103:022607. [PMID: 33736043 DOI: 10.1103/physreve.103.022607] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2020] [Accepted: 01/21/2021] [Indexed: 01/18/2023]
Abstract
Epithelial cell tissues have a slow relaxation dynamics resembling that of supercooled liquids. Yet, they also have distinguishing features. These include an extended short-time subdiffusive transient, as observed in some experiments and recent studies of model systems, and a sub-Arrhenius dependence of the relaxation time on temperature, as reported in numerical studies. Here we demonstrate that the anomalous glassy dynamics of epithelial tissues originates from the emergence of a fractal-like energy landscape, particles becoming virtually free to diffuse in specific phase space directions up to a small distance. Furthermore, we clarify that the stiffness of the cells tunes this anomalous behavior, tissues of stiff cells having conventional glassy relaxation dynamics.
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Affiliation(s)
- Yan-Wei Li
- Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371, Singapore.,School of Physics, Beijing Institute of Technology, Beijing 100081, China
| | - Leon Loh Yeong Wei
- Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371, Singapore
| | - Matteo Paoluzzi
- Departament de Física de la Matèria Condensada, Universitat de Barcelona, C. Martí Franquès 1, 08028 Barcelona, Spain
| | - Massimo Pica Ciamarra
- Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371, Singapore.,CNR-SPIN, Dipartimento di Scienze Fisiche, Università di Napoli Federico II, I-80126, Napoli, Italy
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10
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Paoluzzi M, Angelani L, Puglisi A. Narrow-escape time and sorting of active particles in circular domains. Phys Rev E 2020; 102:042617. [PMID: 33212655 DOI: 10.1103/physreve.102.042617] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2020] [Accepted: 10/04/2020] [Indexed: 06/11/2023]
Abstract
It is now well established that microswimmers can be sorted or segregated fabricating suitable microfluidic devices or using external fields. A natural question is how these techniques can be employed for dividing swimmers of different motility. In this paper, using numerical simulations in the dilute limit, we investigate how motility parameters (time of persistence and velocity) impact the narrow-escape time of active particles from circular domains. We show that the escape time undergoes a crossover between two asymptotic regimes. The control parameters of the crossover is the ratio between the persistence length of the active motion and the typical length scale of the circular domain. We explore the possibility of taking advantage of this finding for sorting active particles by motility parameters.
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Affiliation(s)
- Matteo Paoluzzi
- ISC-CNR, Institute for Complex Systems and Dipartimento di Fisica, Sapienza Università di Roma, Piazzale A. Moro 2, I-00185 Rome, Italy
| | - Luca Angelani
- ISC-CNR, Institute for Complex Systems and Dipartimento di Fisica, Sapienza Università di Roma, Piazzale A. Moro 2, I-00185 Rome, Italy
| | - Andrea Puglisi
- ISC-CNR, Institute for Complex Systems and Dipartimento di Fisica, Sapienza Università di Roma, Piazzale A. Moro 2, I-00185 Rome, Italy
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11
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Abstract
We examine the interplay of motility and information exchange in a model of run-and-tumble active particles where the particle's motility is encoded as a bit of information that can be exchanged upon contact according to the rules of AND and OR logic gates in a circuit. Motile AND particles become non-motile upon contact with a non-motile particle. Conversely, motile OR particles remain motile upon collision with their non-motile counterparts. AND particles that have become non-motile additionally "reawaken", i.e., recover their motility, at a fixed rate μ, as in the SIS (susceptible, infected, susceptible) model of epidemic spreading, where an infected agent can become healthy again, but keeps no memory of the recent infection, hence it is susceptible to a renewed infection. For μ = 0, both AND and OR particles relax irreversibly to absorbing states of all non-motile or all motile particles, respectively. The relaxation kinetics is, however, faster for OR particles that remain active throughout the process. At finite μ, the AND dynamics is controlled by the interplay between reawakening and collision rates. The system evolves to a state of all motile particles (an absorbing state in the language of absorbing phase transitions) for μ > μc and to a mixed state with coexisting motile and non-motile particles (an active state in the language of absorbing phase transitions) for μ < μc. The final state exhibits a rich structure controlled by motility-induced aggregation. Our work can be relevant to biochemical signaling in motile bacteria, the spreading of epidemics and of social consensus, as well as light-controlled organization of active colloids.
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Affiliation(s)
- Matteo Paoluzzi
- ISC-CNR, Institute for Complex Systems, Piazzale A. Moro 2, I-00185 Rome, Italy. and Dipartimento di Fisica, Sapienza University of Rome, Piazzale A. Moro 2, I-00185, Rome, Italy
| | - Marco Leoni
- Université Paris-Saclay, CNRS, IJCLab, 91405, Orsay, France.
| | - M Cristina Marchetti
- Department of Physics, University of California Santa Barbara, Santa Barbara, CA 93106, USA
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12
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Paoluzzi M, Angelani L, Parisi G, Ruocco G. Relation between Heterogeneous Frozen Regions in Supercooled Liquids and Non-Debye Spectrum in the Corresponding Glasses. Phys Rev Lett 2019; 123:155502. [PMID: 31702319 DOI: 10.1103/physrevlett.123.155502] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/29/2019] [Revised: 09/04/2019] [Indexed: 06/10/2023]
Abstract
Recent numerical studies on glassy systems provide evidence for a population of non-Goldstone modes (NGMs) in the low-frequency spectrum of the vibrational density of states D(ω). Similarly to Goldstone modes (GMs), i.e., phonons in solids, NGMs are soft low-energy excitations. However, differently from GMs, NGMs are localized excitations. Here we first show that the parental temperature T^{*} modifies the GM/NGM ratio in D(ω). In particular, the phonon attenuation is reflected in a parental temperature dependency of the exponent s(T^{*}) in the low-frequency power law D(ω)∼ω^{s(T^{*})}, with 2≤s(T^{*})≤4. Second, by comparing s(T^{*}) with s(p), i.e., the same quantity obtained by pinning a p particle fraction, we suggest that s(T^{*}) reflects the presence of dynamical heterogeneous regions of size ξ^{3}∝p. Finally, we provide an estimate of ξ as a function of T^{*}, finding a mild power law divergence, ξ∼(T^{*}-T_{d})^{-α/3}, with T_{d} the dynamical crossover temperature and α falling in the range α∈[0.8,1.0].
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Affiliation(s)
- Matteo Paoluzzi
- Dipartimento di Fisica, Sapienza Università di Roma, Piazzale A. Moro 2, I-00185, Rome, Italy
| | - Luca Angelani
- Dipartimento di Fisica, Sapienza Università di Roma, Piazzale A. Moro 2, I-00185, Rome, Italy
- ISC-CNR, Institute for Complex Systems, Piazzale A. Moro 2, I-00185 Rome, Italy
| | - Giorgio Parisi
- Dipartimento di Fisica, Sapienza Università di Roma, Piazzale A. Moro 2, I-00185, Rome, Italy
- Nanotec-CNR, UOS Rome, Sapienza Università di Roma, Piazzale A. Moro 2, I-00185, Rome, Italy
- INFN-Sezione di Roma 1, Piazzale A. Moro 2, I-00185, Rome
| | - Giancarlo Ruocco
- Dipartimento di Fisica, Sapienza Università di Roma, Piazzale A. Moro 2, I-00185, Rome, Italy
- Center for Life Nano Science, Istituto Italiano di Tecnologia, Viale Regina Elena 291, I-00161, Rome, Italy
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13
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Abstract
Collective cell migration in dense tissues underlies important biological processes, such as embryonic development, wound healing and cancer invasion. While many aspects of single cell movements are now well established, the mechanisms leading to displacements of cohesive cell groups are still poorly understood. To elucidate the emergence of collective migration in mechanosensitive cells, we examine a self-propelled Voronoi (SPV) model of confluent tissues with an orientational feedback that aligns a cell's polarization with its local migration velocity. While shape and motility are known to regulate a density-independent liquid-solid transition in tissues, we find that aligning interactions facilitate collective motion and promote solidification, with transitions that can be predicted by extending statistical physics tools such as effective temperature to this far-from-equilibrium system. In addition to accounting for recent experimental observations obtained with epithelial monolayers, our model predicts structural and dynamical signatures of flocking, which may serve as gateway to a more quantitative characterization of collective motility.
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Affiliation(s)
- Fabio Giavazzi
- Università degli Studi di Milano, Dipartimento di Biotecnologie Mediche e Medicina Traslazionale, 20090 Segrate, Italy.
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14
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Abstract
We study the effect of exponentially correlated noise on the xy model in the limit of small correlation time, discussing the order-disorder transition in the mean field and the topological transition in two dimensions. We map the steady states of the nonequilibrium dynamics into an effective equilibrium theory. In the mean field, the critical temperature increases with the noise correlation time τ, indicating that memory effects promote ordering. This finding is confirmed by numerical simulations. The topological transition temperature in two dimensions remains untouched. However, finite-size effects induce a crossover in the vortices proliferation that is confirmed by numerical simulations.
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Affiliation(s)
- Matteo Paoluzzi
- Department of Physics and Syracuse Soft & Living Matter Program, Syracuse University, Syracuse, New York 13244, USA
| | - Umberto Marini Bettolo Marconi
- Scuola di Scienze e Tecnologie, Università di Camerino, Via Madonna delle Carceri, 62032 Camerino, Italy.,INFN Perugia, 06123 Perugia, Italy
| | - Claudio Maggi
- NANOTEC-CNR, Institute of Nanotechnology, Soft and Living Matter Laboratory, Piazzale A. Moro 2, 00185 Rome, Italy
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15
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Affiliation(s)
| | - Claudio Maggi
- NANOTEC-CNR, Institute of Nanotechnology, Soft and Living Matter Laboratory, Piazzale A. Moro 2, I-00185 Roma, Italy
| | - Matteo Paoluzzi
- Department of Physics, Syracuse University, Syracuse, New York 13244, USA
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16
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Abstract
We investigate the effect of self-propulsion on a mean-field order-disorder transition. Starting from a φ^{4} scalar field theory subject to an exponentially correlated noise, we exploit the unified colored-noise approximation to map the nonequilibrium active dynamics onto an effective equilibrium one. This allows us to follow the evolution of the second-order critical point as a function of the noise parameters: the correlation time τ and the noise strength D. Our results suggest that the universality class of the model remains unchanged. We also estimate the effect of Gaussian fluctuations on the mean-field approximation finding an Ornstein-Zernike-like expression for the static structure factor at long wavelengths. Finally, to assess the validity of our predictions, we compare the mean-field theoretical results with numerical simulations of active Lennard-Jones particles in two and three dimensions, finding good qualitative agreement at small τ values.
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Affiliation(s)
- M Paoluzzi
- Department of Physics, Syracuse University, Syracuse, New York 13244, USA
| | - C Maggi
- NANOTEC-CNR, Institute of Nanotechnology, Soft and Living Matter Laboratory, Piazzale A. Moro 2, I-00185, Roma, Italy
| | - U Marini Bettolo Marconi
- Scuola di Scienze e Tecnologie, Università di Camerino, Via Madonna delle Carceri, 62032 Camerino, Italy and INFN, Sezione di Perugia, Via A. Pascoli, 06123 Perugia, Italy
| | - N Gnan
- CNR, ISC, UOS Sapienza, Piazzale Aldo Moro 2, 00185 Roma, Italy
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17
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Paoluzzi M, Di Leonardo R, Marchetti MC, Angelani L. Shape and Displacement Fluctuations in Soft Vesicles Filled by Active Particles. Sci Rep 2016; 6:34146. [PMID: 27678166 PMCID: PMC5039690 DOI: 10.1038/srep34146] [Citation(s) in RCA: 50] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2016] [Accepted: 09/07/2016] [Indexed: 11/09/2022] Open
Abstract
We investigate numerically the dynamics of shape and displacement fluctuations of two-dimensional flexible vesicles filled with active particles. At low concentration most of the active particles accumulate at the boundary of the vesicle where positive particle number fluctuations are amplified by trapping, leading to the formation of pinched spots of high density, curvature and pressure. At high concentration the active particles cover the vesicle boundary almost uniformly, resulting in fairly homogeneous pressure and curvature, and nearly circular vesicle shape. The change between polarized and spherical shapes is driven by the number of active particles. The center-of-mass of the vesicle performs a persistent random walk with a long time diffusivity that is strongly enhanced for elongated active particles due to orientational correlations in their direction of propulsive motion. In our model shape-shifting induces directional sensing and the cell spontaneously migrate along the polarization direction.
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Affiliation(s)
- Matteo Paoluzzi
- Department of Physics and Syracuse Soft Matter Program, Syracuse University, Syracuse NY 13244, USA.,Dipartimento di Fisica Università Sapienza, P.le A Moro 2, 00185 Rome, Italy
| | - Roberto Di Leonardo
- Dipartimento di Fisica Università Sapienza, P.le A Moro 2, 00185 Rome, Italy.,NANOTEC-CNR, Institute of Nanotechnology, Soft and Living Matter Laboratory, Piazzale A. Moro 2, I-00185, Roma, Italy
| | - M Cristina Marchetti
- Department of Physics and Syracuse Soft Matter Program, Syracuse University, Syracuse NY 13244, USA
| | - Luca Angelani
- Dipartimento di Fisica Università Sapienza, P.le A Moro 2, 00185 Rome, Italy.,ISC-CNR, Institute for Complex Systems, Piazzale A. Moro 2, I-00185 Roma, Italy
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18
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Affiliation(s)
| | - Matteo Paoluzzi
- Department of Physics, Syracuse University, Syracuse, NY, USA
| | - Claudio Maggi
- Dipartimento di Fisica, Universita Sapienza, Rome, Italy
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19
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Lettry J, Aguglia D, Alessi J, Andersson P, Bertolo S, Briefi S, Butterworth A, Coutron Y, Dallocchio A, David N, Chaudet E, Faircloth D, Fantz U, Fink DA, Garlasche M, Grudiev A, Guida R, Hansen J, Haase M, Hatayama A, Jones A, Koszar I, Lallement JB, Lombardi AM, Machado C, Mastrostefano C, Mathot S, Mattei S, Moyret P, Nisbet D, Nishida K, O'Neil M, Paoluzzi M, Scrivens R, Shibata T, Steyaert D, Thaus N, Voulgarakis G. Linac4 H⁻ ion sources. Rev Sci Instrum 2016; 87:02B139. [PMID: 26932021 DOI: 10.1063/1.4936120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
CERN's 160 MeV H(-) linear accelerator (Linac4) is a key constituent of the injector chain upgrade of the Large Hadron Collider that is being installed and commissioned. A cesiated surface ion source prototype is being tested and has delivered a beam intensity of 45 mA within an emittance of 0.3 π ⋅ mm ⋅ mrad. The optimum ratio of the co-extracted electron- to ion-current is below 1 and the best production efficiency, defined as the ratio of the beam current to the 2 MHz RF-power transmitted to the plasma, reached 1.1 mA/kW. The H(-) source prototype and the first tests of the new ion source optics, electron-dump, and front end developed to minimize the beam emittance are presented. A temperature regulated magnetron H(-) source developed by the Brookhaven National Laboratory was built at CERN. The first tests of the magnetron operated at 0.8 Hz repetition rate are described.
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Affiliation(s)
- J Lettry
- CERN-ABP, 1211 Geneva 23, Switzerland
| | - D Aguglia
- CERN-ABP, 1211 Geneva 23, Switzerland
| | - J Alessi
- Brookhaven National Laboratory, BNL-CA, Upton, New York 11973, USA
| | | | - S Bertolo
- CERN-ABP, 1211 Geneva 23, Switzerland
| | - S Briefi
- AG Experimentelle Plasmaphysik, Universität Augsburg, 86135 Augsburg, Germany
| | | | - Y Coutron
- CERN-ABP, 1211 Geneva 23, Switzerland
| | | | - N David
- CERN-ABP, 1211 Geneva 23, Switzerland
| | - E Chaudet
- CERN-ABP, 1211 Geneva 23, Switzerland
| | - D Faircloth
- RAL, Harwell Oxford, Didcot OX11 0QX, United Kingdom
| | - U Fantz
- AG Experimentelle Plasmaphysik, Universität Augsburg, 86135 Augsburg, Germany
| | - D A Fink
- CERN-ABP, 1211 Geneva 23, Switzerland
| | | | - A Grudiev
- CERN-ABP, 1211 Geneva 23, Switzerland
| | - R Guida
- CERN-ABP, 1211 Geneva 23, Switzerland
| | - J Hansen
- CERN-ABP, 1211 Geneva 23, Switzerland
| | - M Haase
- CERN-ABP, 1211 Geneva 23, Switzerland
| | - A Hatayama
- Graduate School of Science and Technology, Keio University, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama 223-8522, Japan
| | - A Jones
- CERN-ABP, 1211 Geneva 23, Switzerland
| | - I Koszar
- CERN-ABP, 1211 Geneva 23, Switzerland
| | | | | | - C Machado
- CERN-ABP, 1211 Geneva 23, Switzerland
| | | | - S Mathot
- CERN-ABP, 1211 Geneva 23, Switzerland
| | - S Mattei
- CERN-ABP, 1211 Geneva 23, Switzerland
| | - P Moyret
- CERN-ABP, 1211 Geneva 23, Switzerland
| | - D Nisbet
- CERN-ABP, 1211 Geneva 23, Switzerland
| | - K Nishida
- Graduate School of Science and Technology, Keio University, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama 223-8522, Japan
| | - M O'Neil
- CERN-ABP, 1211 Geneva 23, Switzerland
| | | | | | - T Shibata
- Graduate School of Science and Technology, Keio University, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama 223-8522, Japan
| | | | - N Thaus
- CERN-ABP, 1211 Geneva 23, Switzerland
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20
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Rainone C, Ferrari U, Paoluzzi M, Leuzzi L. Dynamical arrest with zero complexity: The unusual behavior of the spherical Blume-Emery-Griffiths disordered model. Phys Rev E Stat Nonlin Soft Matter Phys 2015; 92:062150. [PMID: 26764675 DOI: 10.1103/physreve.92.062150] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/22/2015] [Indexed: 06/05/2023]
Abstract
The short- and long-time dynamics of model systems undergoing a glass transition with apparent inversion of Kauzmann and dynamical arrest glass transition lines is investigated. These models belong to the class of the spherical mean-field approximation of a spin-1 model with p-body quenched disordered interaction, with p>2, termed spherical Blume-Emery-Griffiths models. Depending on temperature and chemical potential the system is found in a paramagnetic or in a glassy phase and the transition between these phases can be of a different nature. In specific regions of the phase diagram coexistence of low-density and high-density paramagnets can occur, as well as the coexistence of spin-glass and paramagnetic phases. The exact static solution for the glassy phase is known to be obtained by the one-step replica symmetry breaking ansatz. Different scenarios arise for both the dynamic and the thermodynamic transitions. These include: (i) the usual random first-order transition (Kauzmann-like) for mean-field glasses preceded by a dynamic transition, (ii) a thermodynamic first-order transition with phase coexistence and latent heat, and (iii) a regime of apparent inversion of static transition line and dynamic transition lines, the latter defined as a nonzero complexity line. The latter inversion, though, turns out to be preceded by a dynamical arrest line at higher temperature. Crossover between different regimes is analyzed by solving mode-coupling-theory equations near the boundaries of paramagnetic solutions and the relationship with the underlying statics is discussed.
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Affiliation(s)
- Corrado Rainone
- Dipartimento di Fisica, Sapienza Università di Roma, Piazzale A. Moro 2, I-00185 Roma, Italy
- LPT, Ecole Normale Supérieure, CNRS UMR 8549, 24 Rue Lhomond, 75005 Paris, France
| | - Ulisse Ferrari
- Institut de la Vision, Sorbonne Universités, UPMC, INSERM U968, CNRS UMR 7210, Paris, F-75012, France
| | - Matteo Paoluzzi
- Department of Physics, Syracuse University, Syracuse NY 13244, USA
| | - Luca Leuzzi
- Dipartimento di Fisica, Sapienza Università di Roma, Piazzale A. Moro 2, I-00185 Roma, Italy
- NANOTEC-CNR, Soft and Living Matter Lab. Rome, c/o Dept. Physics, Sapienza Università di Roma, Piazzale A. Moro 2, I-00185 Roma, Italy
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21
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Paoluzzi M, Di Leonardo R, Angelani L. Self-Sustained Density Oscillations of Swimming Bacteria Confined in Microchambers. Phys Rev Lett 2015; 115:188303. [PMID: 26565506 DOI: 10.1103/physrevlett.115.188303] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/02/2014] [Indexed: 06/05/2023]
Abstract
We numerically study the dynamics of run-and-tumble particles confined in two chambers connected by thin channels. Two dominant dynamical behaviors emerge: (i) an oscillatory pumping state, in which particles periodically fill the two vessels, and (ii) a circulating flow state, dynamically maintaining a near constant population level in the containers when connected by two channels. We demonstrate that the oscillatory behavior arises from the combination of a narrow channel, preventing bacteria reorientation, and a density-dependent motility inside the chambers.
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Affiliation(s)
- M Paoluzzi
- Dipartimento di Fisica Università Sapienza, P.le A Moro 2, 00185 Rome, Italy
| | - R Di Leonardo
- Dipartimento di Fisica Università Sapienza, P.le A Moro 2, 00185 Rome, Italy
- NANOTEC-CNR, Institute of Nanotechnology, Soft and Living Matter Laboratory, Piazzale A. Moro 2, I-00185 Roma, Italy
| | - L Angelani
- Dipartimento di Fisica Università Sapienza, P.le A Moro 2, 00185 Rome, Italy
- Istituto dei Sistemi Complessi (ISC-CNR), UOS Sapienza, P.le A Moro 2, 00185 Rome, Italy
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22
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Maggi C, Paoluzzi M, Pellicciotta N, Lepore A, Angelani L, Di Leonardo R. Generalized energy equipartition in harmonic oscillators driven by active baths. Phys Rev Lett 2014; 113:238303. [PMID: 25526168 DOI: 10.1103/physrevlett.113.238303] [Citation(s) in RCA: 88] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/18/2014] [Indexed: 06/04/2023]
Abstract
We study experimentally and numerically the dynamics of colloidal beads confined by a harmonic potential in a bath of swimming E. coli bacteria. The resulting dynamics is well approximated by a Langevin equation for an overdamped oscillator driven by the combination of a white thermal noise and an exponentially correlated active noise. This scenario leads to a simple generalization of the equipartition theorem resulting in the coexistence of two different effective temperatures that govern dynamics along the flat and the curved directions in the potential landscape.
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Affiliation(s)
- Claudio Maggi
- Dipartimento di Fisica, Università di Roma "Sapienza," I-00185 Roma, Italy
| | - Matteo Paoluzzi
- CNR-IPCF, UOS Roma, Dipartimento di Fisica Università Sapienza, I-00185 Roma, Italy
| | | | - Alessia Lepore
- Dipartimento di Fisica, Università di Roma "Sapienza," I-00185 Roma, Italy
| | - Luca Angelani
- CNR-IPCF, UOS Roma, Dipartimento di Fisica Università Sapienza, I-00185 Roma, Italy
| | - Roberto Di Leonardo
- Dipartimento di Fisica, Università di Roma "Sapienza," I-00185 Roma, Italy and CNR-IPCF, UOS Roma, Dipartimento di Fisica Università Sapienza, I-00185 Roma, Italy
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23
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Abstract
The random energy landscapes developed by speckle fields can be used to confine and manipulate a large number of micro-particles with a single laser beam. By means of molecular dynamics simulations, we investigate the static and dynamic properties of an active suspension of swimming bacteria embedded into speckle patterns. Looking at the correlation of the density fluctuations and the equilibrium density profiles, we observe a crossover phenomenon when the forces exerted by the speckles are equal to the bacteria's propulsion.
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Affiliation(s)
- M Paoluzzi
- CNR-IPCF, UOS Roma, Dipartimento di Fisica, Università Sapienza, P.le Aldo Moro 2, I-00185, Rome, Italy
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24
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Angelani L, Di Leonardo R, Paoluzzi M. First-passage time of run-and-tumble particles. Eur Phys J E Soft Matter 2014; 37:15. [PMID: 25015558 DOI: 10.1140/epje/i2014-14059-4] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/09/2014] [Revised: 06/06/2014] [Accepted: 06/13/2014] [Indexed: 06/03/2023]
Abstract
We solve the problem of first-passage time for run-and-tumble particles in one dimension. Exact expression is derived for the mean first-passage time in the general case, considering external force fields and chemotactic fields, giving rise to space-dependent swim speed and tumble rate. Agreement between theoretical formulae and numerical simulations is obtained in the analyzed case studies --constant and sinusoidal force fields, constant gradient chemotactic field. Reported findings can be useful to get insights into very different phenomena involving active particles, such as bacterial motion in external fields, intracellular transport, cell migration, animal foraging.
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Affiliation(s)
- L Angelani
- CNR-IPCF, UOS Roma c/o Dip. di Fisica Università "Sapienza", I-00185, Roma, Italy,
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25
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Grudiev A, Lettry J, Mattei S, Paoluzzi M, Scrivens R. Numerical simulation of electromagnetic fields and impedance of CERN LINAC4 H(-) source taking into account the effect of the plasma. Rev Sci Instrum 2014; 85:02B134. [PMID: 24593574 DOI: 10.1063/1.4842317] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Numerical simulation of the CERN LINAC4 H(-) source 2 MHz RF system has been performed taking into account a realistic geometry from 3D Computer Aided Design model using commercial FEM high frequency simulation code. The effect of the plasma has been added to the model by the approximation of a homogenous electrically conducting medium. Electric and magnetic fields, RF power losses, and impedance of the circuit have been calculated for different values of the plasma conductivity. Three different regimes have been found depending on the plasma conductivity: (1) Zero or low plasma conductivity results in RF electric field induced by the RF antenna being mainly capacitive and has axial direction; (2) Intermediate conductivity results in the expulsion of capacitive electric field from plasma and the RF power coupling, which is increasing linearly with the plasma conductivity, is mainly dominated by the inductive azimuthal electric field; (3) High conductivity results in the shielding of both the electric and magnetic fields from plasma due to the skin effect, which reduces RF power coupling to plasma. From these simulations and measurements of the RF power coupling on the CERN source, a value of the plasma conductivity has been derived. It agrees well with an analytical estimate calculated from the measured plasma parameters. In addition, the simulated and measured impedances with and without plasma show very good agreement as well demonstrating validity of the plasma model used in the RF simulations.
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26
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Lettry J, Aguglia D, Andersson P, Bertolo S, Butterworth A, Coutron Y, Dallocchio A, Chaudet E, Gil-Flores J, Guida R, Hansen J, Hatayama A, Koszar I, Mahner E, Mastrostefano C, Mathot S, Mattei S, Midttun Ø, Moyret P, Nisbet D, Nishida K, O'Neil M, Ohta M, Paoluzzi M, Pasquino C, Pereira H, Rochez J, Sanchez Alvarez J, Sanchez Arias J, Scrivens R, Shibata T, Steyaert D, Thaus N, Yamamoto T. Status and operation of the Linac4 ion source prototypes. Rev Sci Instrum 2014; 85:02B122. [PMID: 24593562 DOI: 10.1063/1.4848975] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
CERN's Linac4 45 kV H(-) ion sources prototypes are installed at a dedicated ion source test stand and in the Linac4 tunnel. The operation of the pulsed hydrogen injection, RF sustained plasma, and pulsed high voltages are described. The first experimental results of two prototypes relying on 2 MHz RF-plasma heating are presented. The plasma is ignited via capacitive coupling, and sustained by inductive coupling. The light emitted from the plasma is collected by viewports pointing to the plasma chamber wall in the middle of the RF solenoid and to the plasma chamber axis. Preliminary measurements of optical emission spectroscopy and photometry of the plasma have been performed. The design of a cesiated ion source is presented. The volume source has produced a 45 keV H(-) beam of 16-22 mA which has successfully been used for the commissioning of the Low Energy Beam Transport (LEBT), Radio Frequency Quadrupole (RFQ) accelerator, and chopper of Linac4.
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Affiliation(s)
- J Lettry
- CERN, 1211 Geneva 23, Switzerland
| | | | | | | | | | | | | | | | | | - R Guida
- CERN, 1211 Geneva 23, Switzerland
| | - J Hansen
- CERN, 1211 Geneva 23, Switzerland
| | - A Hatayama
- Graduate School of Science and Technology, Keio University, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama 223-8522, Japan
| | - I Koszar
- CERN, 1211 Geneva 23, Switzerland
| | - E Mahner
- CERN, 1211 Geneva 23, Switzerland
| | | | - S Mathot
- CERN, 1211 Geneva 23, Switzerland
| | - S Mattei
- CERN, 1211 Geneva 23, Switzerland
| | | | - P Moyret
- CERN, 1211 Geneva 23, Switzerland
| | - D Nisbet
- CERN, 1211 Geneva 23, Switzerland
| | - K Nishida
- Graduate School of Science and Technology, Keio University, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama 223-8522, Japan
| | - M O'Neil
- CERN, 1211 Geneva 23, Switzerland
| | - M Ohta
- Graduate School of Science and Technology, Keio University, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama 223-8522, Japan
| | | | | | | | - J Rochez
- CERN, 1211 Geneva 23, Switzerland
| | | | | | | | - T Shibata
- Graduate School of Science and Technology, Keio University, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama 223-8522, Japan
| | | | - N Thaus
- CERN, 1211 Geneva 23, Switzerland
| | - T Yamamoto
- Graduate School of Science and Technology, Keio University, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama 223-8522, Japan
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27
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Abstract
E. coli bacteria swim in straight runs interrupted by sudden reorientation events called tumbles. The resulting random walks give rise to density fluctuations that can be derived analytically in the limit of non-interacting particles or equivalently of very low concentrations. However, in situations of practical interest, the concentration of bacteria is always large enough to make interactions an important factor. Using molecular dynamics simulations, we study the dynamic structure factor of a model bacterial bath for increasing values of densities. We show that it is possible to reproduce the dynamics of density fluctuations in the system using a free run-and-tumble model with effective fitting parameters. We discuss the dependence of these parameters, e.g., the tumbling rate, tumbling time and self-propulsion velocity, on the density of the bath.
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Affiliation(s)
- M Paoluzzi
- Dipartimento de Fisica, CNR-IPCF, UOS Roma, Università Sapienza, Piazzale Aldo Moro 2, I-00185, Rome, Italy
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28
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Kronberger M, Faircloth D, Lettry J, Paoluzzi M, Pereira H, Sanchez Arias J, Schmitzer C, Scrivens R. Status of the plasma generator of the superconducting proton linac. Rev Sci Instrum 2012; 83:02A703. [PMID: 22380212 DOI: 10.1063/1.3662478] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
In the framework of the superconducting proton linac (SPL) study at CERN, a new non-cesiated H(-) plasma generator driven by an external 2 MHz RF antenna has been developed and successfully operated at repetition rates of 50 Hz, pulse lengths of up to 3 ms, and average RF powers of up to 3 kW. The coupling efficiency of RF power into the plasma was determined by the cooling water temperatures and the analysis of the RF forward and reflected power and the antenna current and amounts to 50%-60%. The plasma resistance increases between 10 kW and 40 kW RF power from about 0.45 Ω to 0.65 Ω. Measurements of RF power dissipated in the ferrites and the magnets on a test bench show a 5-fold decrease of the power losses for the magnets when they are contained in a Cu box, thus validating the strategy of shielding the magnets with a high electrical conductivity material. An air cooling system was installed in the SPL plasma generator to control the temperatures of the ferrites despite hysteresis losses of several Watts.
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Affiliation(s)
- M Kronberger
- European Organisation for Nuclear Research, CERN, 1211 Geneva 23, Switzerland.
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29
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Lettry J, Fantz U, Kronberger M, Kalvas T, Koivisto H, Komppula J, Mahner E, Schmitzer C, Sanchez J, Scrivens R, Midttun O, Myllyperkiö P, O'Neil M, Pereira H, Paoluzzi M, Tarvainen O, Wünderlich D. Optical emission spectroscopy of the Linac4 and superconducting proton Linac plasma generators. Rev Sci Instrum 2012; 83:02A729. [PMID: 22380238 DOI: 10.1063/1.3680079] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
CERN's superconducting proton Linac (SPL) study investigates a 50 Hz high-energy, high-power Linac for H(-) ions. The SPL plasma generator is an evolution of the DESY ion source plasma generator currently operated at CERN's Linac4 test stand. The plasma generator is a step towards a particle source for the SPL, it is designed to handle 100 kW peak RF-power at a 6% duty factor. While the acquisition of an integrated hydrogen plasma optical spectrum is straightforward, the measurement of a time-resolved spectrum requires dedicated amplification schemes. The experimental setup for visible light based on photomultipliers and narrow bandwidth filters and the UV spectrometer setup are described. The H(α), H(β), and H(γ) Balmer line intensities, the Lyman band and alpha transition were measured. A parametric study of the optical emission from the Linac4 ion source and the SPL plasma generator as a function of RF-power and gas pressure is presented. The potential of optical emission spectrometry coupled to RF-power coupling measurements for on-line monitoring of short RF heated hydrogen plasma pulses is discussed.
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Affiliation(s)
- J Lettry
- European Organization for Nuclear Research, CERN, 1211 Geneva 23, Switzerland.
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30
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Crisanti A, Leuzzi L, Paoluzzi M. Statistical mechanical approach to secondary processes and structural relaxation in glasses and glass formers: a leading model to describe the onset of Johari-Goldstein processes and their relationship with fully cooperative processes. Eur Phys J E Soft Matter 2011; 34:98. [PMID: 21947889 DOI: 10.1140/epje/i2011-11098-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/01/2011] [Revised: 07/25/2011] [Accepted: 07/26/2011] [Indexed: 05/31/2023]
Abstract
The interrelation of dynamic processes active on separated time-scales in glasses and viscous liquids is investigated using a model displaying two time-scale bifurcations both between fast and secondary relaxation and between secondary and structural relaxation. The study of the dynamics allows for predictions on the system relaxation above the temperature of dynamic arrest in the mean-field approximation, that are compared with the outcomes of the equations of motion directly derived within the Mode Coupling Theory (MCT) for under-cooled viscous liquids. By varying the external thermodynamic parameters, a wide range of phenomenology can be represented, from a very clear separation of structural and secondary peak in the susceptibility loss to excess wing structures.
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Affiliation(s)
- A Crisanti
- Dipartimento di Fisica, Università Sapienza, Piazzale Aldo Moro, 5 - 00185 - Rome, Italy
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Paoluzzi M, Leuzzi L, Crisanti A. Thermodynamic first order transition and inverse freezing in a 3D spin glass. Phys Rev Lett 2010; 104:120602. [PMID: 20366522 DOI: 10.1103/physrevlett.104.120602] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/10/2009] [Revised: 03/09/2010] [Indexed: 05/29/2023]
Abstract
We present a numerical study of the random Blume-Capel model in three dimensions. The phase diagram is characterized by spin-glass-paramagnet phase transitions of both first and second order in the thermodynamic sense. Numerical simulations are performed using the exchange Monte Carlo algorithm, providing clear evidence for inverse freezing. The main features at criticality and in the phase coexistence region are investigated. We are not privy to other 3D short-range systems with quenched disorder undergoing inverse freezing.
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Affiliation(s)
- M Paoluzzi
- IPCF-CNR, UOS Roma, Piazzale Aldo Moro 2, I-00185 Roma, Italy
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Kronberger M, Küchler D, Lettry J, Midttun Ø, O'Neil M, Paoluzzi M, Scrivens R. Commissioning of the new H- source for Linac4. Rev Sci Instrum 2010; 81:02A708. [PMID: 20192378 DOI: 10.1063/1.3278587] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
As part of the CERN accelerator complex upgrade, a new linear accelerator for H(-) (Linac4) will start its operation in 2014. The source for this linac will be a 2 MHz rf driven H(-) source which is a copy of the very successful source from DESY. In this paper the design and the first results of the commissioning are reported. The commissioning has progressed successfully, and no major obstacles have been identified which will prevent reaching the goal of 80 mA H(-) beam current, 45 keV beam energy, 0.4 ms pulse length, and 2 Hz repetition rate. The source is producing up until now a stable beam of 23 mA, 35 keV, and with a repetition rate of 0.83 Hz.
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Affiliation(s)
- M Kronberger
- Department of Beams, CERN, CH1211 Geneva, Switzerland
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Lettry J, Kronberger M, Scrivens R, Chaudet E, Faircloth D, Favre G, Geisser JM, Küchler D, Mathot S, Midttun O, Paoluzzi M, Schmitzer C, Steyaert D. High duty factor plasma generator for CERN's Superconducting Proton Linac. Rev Sci Instrum 2010; 81:02A723. [PMID: 20192392 DOI: 10.1063/1.3277188] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
CERN's Linac4 is a 160 MeV linear accelerator currently under construction. It will inject negatively charged hydrogen ions into CERN's PS-Booster. Its ion source is a noncesiated rf driven H(-) volume source directly inspired from the one of DESY and is aimed to deliver pulses of 80 mA of H(-) during 0.4 ms at a 2 Hz repetition rate. The Superconducting Proton Linac (SPL) project is part of the luminosity upgrade of the Large Hadron Collider. It consists of an extension of Linac4 up to 5 GeV and is foreseen to deliver protons to a future 50 GeV synchrotron (PS2). For the SPL high power option (HP-SPL), the ion source would deliver pulses of 80 mA of H(-) during 1.2 ms and operate at a 50 Hz repetition rate. This significant upgrade motivates the design of the new water cooled plasma generator presented in this paper. Its engineering is based on the results of a finite element thermal study of the Linac4 H(-) plasma generator that identified critical components and thermal barriers. A cooling system is proposed which achieves the required heat dissipation and maintains the original functionality. Materials with higher thermal conductivity are selected and, wherever possible, thermal barriers resulting from low pressure contacts are removed by brazing metals on insulators. The AlN plasma chamber cooling circuit is inspired from the approach chosen for the cesiated high duty factor rf H(-) source operating at SNS.
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Affiliation(s)
- J Lettry
- CERN, CH1211 Geneva, Switzerland.
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Paoluzzi M, Cuttano MG, Mugnaini P, Salsano F, Giannotti P. Urinary dosage of nuclear matrix protein 22 (NMP22) like biologic marker of transitional cell carcinoma (TCC): a study on patients with hematuria. Arch Ital Urol Androl 1999; 71:13-8. [PMID: 10193018] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/11/2023] Open
Abstract
UNLABELLED This study was performed to evaluate the clinical usefulness of nuclear matrix protein 22 (NMP22) as urinary marker for bladder cancer and to define its role in comparison with urinary cytology in diagnostic management of patients with hematuria. MATERIALS AND METHODS NMP22 values in voided urines were determined on 90 patients (81 males, 14 females) with macro or microscopical hematuria, using the NMP22 test-kit (Matritech) based on an enzyme-linked immuno-sorbant assay. The cut-off value for positive samples was 10U/ml. In all cases urinary cytology was performed on the same sample. Patients suspected for the presence of a transitional cell carcinoma (TCC) underwent cytoscopic control. Statistical signification of the medians difference was analyzed using both medians variance analysis and Student's test. The increasing in diagnostic predictivity was analyzed elaborating contingency tables and performing consequently chi 2 test. RESULTS 32 cases of TCC were endoscopically detected: sensitivity of cytopathology was 75.8%, specificity was 62.5%. The positive predictive value of the cytology was 22% and negative predictive value was 49%. The results concerning NMP22 dosage are: sensitivity 84%, specificity 62%. Positive predictive value of NMP22 test was 30% and predictive negative value was 40%. No significant differences between cytopathology and NMP22 dosage were founded (p > 0.995). Considering both cytopathology and NMP22 dosage, sensitivity was 82.7% and specificity raises up to 90.6% with statistical signification (P < 0.001). The median NMP22 value in patients affected by TCC endoscopically confirmed (group A) was 55.2 U/ml, in subjects with no evidence of malignancy (group B) it was 19.1 U/ml. The difference shows statistical signification (p < 0.001). In 20 cases with TCC, hystological grading were available and were investigated in relationship with NMP22 title in U/ml, median NMP22 value for each grade was: CIS = 102 U/ml, G0 = 35 U/ml, G1 = 30 U/ml, G2 = 66 U/ml, G3 = 54 U/ml. It can be assessed that NMP22 test is useful in differentiating subjects affected by TCC from subjects with no evidence of malignancy and may help in early diagnosis of TCC and in predicting recurrent even if low grade tumors especially if used in association with cytology and endoscopy.
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Affiliation(s)
- M Paoluzzi
- Department of Surgery, University of Pisa, Italia
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Migliari R, Pistolesi D, Solinas A, Paoluzzi M, Giannotti P, Usai E. [Four corner bladder base and bladder neck suspension with intraosseous anchorage in the treatment of moderate cystocele]. Chir Ital 1998; 50:7-16. [PMID: 9732818] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
During the last 10 years the original Pereyra technique of needle bladder neck suspension has been object of more than 36 modifications with the goal to improve long term results and to enhance feasibility. It represents also a part of the so called four corner bladder and bladder neck suspension (anterior suspending sutures) which is at present a reliable and durable manner to manage mild to moderate cystocele; this procedure reestablishes safely and simply support to bladder base, bladder neck and urethra preventing the onset of a denovo stress urinary incontinence. Complications include post-operative pain which could represent a problem in about 16% of the patients: it has been related to the entrapment of the ileoinguinal nerve between prolene sutures and rectus fascia and may be responsible of a delay in the re-establishment of a normal voiding pattern due to the pain elicited during any rectus muscle contraction. We propose a refinement of this procedure which includes the osseous anchoring of the suspending suture through the Mitek G II anchor system. Reduction in postoperative pain and fast recovery of a normal voiding pattern soon after surgery seems to be the most important result of this modification. Osteitis pubis has not been noted. Any improvement in long term durability of the procedure has not yet been determined due to the short follow-up and limited series of cases and the need for subsequent long term follow-up.
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Affiliation(s)
- R Migliari
- Clinica Urologica, Università degli Studi di Cagliari
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