Search results for " ANS"

showing 10 items of 134 documents

Cultural institutions as agents of urban and community regeneration in the (post-)pandemic city. The case of the «Laboratorio Zen Insieme» in Palermo

2022

Although all cities in the world have been affected by the COVID-19 pandemic, its impacts on the territories, yet to be understood, are unevenly distributed, revealing extremely varied imbalances depending on the places. However, it is clear that the virus and its variants have aggravated pre-existing socio-spatial inequalities, creating new ones and bringing attention back to those implications between space, planning, public health and citizenship that are at the origins of contemporary urbanism. In a reference framework in which the crisis is globalized but unequal and in the absence of a welfare system capable of responding to the urgencies of the most marginalized social contexts and g…

Olsen 2018Settore ICAR/21 - UrbanisticaSettore M-GGR/01 - GeografiaSacco and Blessi 2009). In the current (post-) pandemic context and through the lens of a southern European perspective the purpose of this article is to critically reflect about the role of culture as possible vehicle of urban and community regeneration. In particular we will focus on the activities of the no profit organization «Laboratorio Zen Insieme» in ZEN2 one of the last large popular and peripheral neighborhoods built in Palermo at the end of 80s in order to explore and understand how cultural practices work as agent of urban and social transformation capable of addressing emerging issues especially in the pandemic scenario we are experiencing. Thecasestudy has been conducted through analysis of documents participative observations (Honer and Hitzler 2015) and qualitative in-depth interviews with key actors involved in the conception organization and management of the activities carried out by Laboratorio Zen Insieme with representatives of local institutions and non-formal conversations with participants of the workshops heldin the neighborhood. The experience we narrate finds that cultural practices have re-conceptualized their design and functions as strategies of urban and community regeneration and at the same time have contributed to answer to emergent issues in developing proximity and local based strategies facing up to problems inherent civil rights educationalpoverty socio-spatial justice and have changed the image and identity of urban places they inhabit.In this sense the research provides a framework for development of strategies and legitimization for cultural practices and a point of discussionabouttheirrolein urban development.Although all cities in the world have been affected by the COVID-19 pandemic its impacts on the territories yet to be understood are unevenly distributed revealing extremely varied imbalances depending on the places. However it is clear that the virus and its variants have aggravated pre-existing socio-spatial inequalities creating new ones and bringing attention back to those implications between space planning public health and citizenship that are at the origins of contemporary urbanism. In a reference framework in which the crisis is globalized but unequal and in the absence of a welfare system capable of responding to the urgencies of the most marginalized social contexts and groups a response to the new social and individual needs has been offered by cultural institutions that play a role of territorial agency often independently or in the absence of political institutions. Far from the idea of entertainment and divertissement it is in fact increasingly clear how the practices of cultural innovation experimenting with various forms of action and participation can in some cases play a fundamental role in the processes of social cohesion and community building representing an antidote to the worsening of the phenomena of marginalization and socio-spatial inequalities within cities and territories (Colantonio and Dixon 2011
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Le mineur de 13 ans au seuil de la responsabilité pénale

2019

International audience

Ordonnance de 1945[SHS.DROIT]Humanities and Social Sciences/Law[SHS.DROIT] Humanities and Social Sciences/LawAge de 13 ansResponsabilité PénaleRéformeComputingMilieux_MISCELLANEOUSMineur
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The band structure of double excited states for a linear chain

2000

Abstract The energy band structure in the case of double excited states of finite spin systems (s= 1 2 ) has been investigated. A geometrical construction based on the Bethe Ansatz method for determining eigenstates has been proposed. The formula for energy spectrum in the center and at the border of Brillouin zone has been obtained. Classification of energy bands has been elaborated on and approximated dispersion law for bounded states given. Some problems with application of the Bethe Ansatz in the case of finite system has been pointed out.

PhysicsCondensed Matter PhysicsElectronic Optical and Magnetic MaterialsBethe ansatzBrillouin zoneQuantum mechanicsBounded functionExcited stateQuantum electrodynamicsDispersion relationElectrical and Electronic EngineeringElectronic band structureEigenvalues and eigenvectorsSpin-½Physica B: Condensed Matter
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Spectral Function of the One-Dimensional Hubbard Model away from Half Filling

2004

We calculate the photoemission spectral function of the one-dimensional Hubbard model away from half filling using the dynamical density matrix renormalization group method. An approach for calculating momentum-dependent quantities in finite open chains is presented. Comparison with exact Bethe Ansatz results demonstrates the unprecedented accuracy of our method. Our results show that the photoemission spectrum of the quasi-one-dimensional conductor TTF-TCNQ provides evidence for spin-charge separation on the scale of the conduction band width.

PhysicsDensity matrixStrongly Correlated Electrons (cond-mat.str-el)Hubbard modelFOS: Physical sciencesGeneral Physics and AstronomyRenormalization groupThermal conductionSpinonBethe ansatzConductorCondensed Matter - Strongly Correlated ElectronsLuttinger liquidQuantum electrodynamicsQuantum mechanicsCondensed Matter::Strongly Correlated ElectronsPhysical Review Letters
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Dynamical behaviour of an XX central spin model through Bethe ansatz techniques

2009

Following the Bethe ansazt procedure the exact dynamics of an XX central spin model is revealed. Particular initial conditions are analyzed and the consequent time evolution is compared with the exact solution obtained by solving the time-dependent Schrudinger equation. The interest towards spin systems and in particular central spin systems, is motivated by the recent developments in more applicative contexts.

PhysicsExact solutions in general relativityQuantum mechanicsSpin modelTime evolutionCondensed Matter::Strongly Correlated ElectronsStatistical and Nonlinear PhysicsMathematical PhysicsBethe ansatzMathematical physicsSpin-½Reports on Mathematical Physics
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Classical thermodynamics of the Heisenberg chain in a field by generalized Bethe ansatz method

1990

Abstract Using the classical action-angle variables for the continuous model, we study the thermodynamics of the classical Heisenberg chain in an applied field by a generalized Bethe ansatz approach. The crucial point consists in the derivation of a phase-shifted density of states for the excitations of the model, obtained by imposing periodic boundary conditions. In the thermodynamic limit, the free energy can be expressed in terms of the solution of a non-linear integral equation, showing the universal dependece of the variable x=(JH) 1 2 /T .

PhysicsHeisenberg modelGeneral Physics and AstronomyThermodynamicssine-Gordon equationIntegral equationBethe ansatzsymbols.namesakeThermodynamic limitsymbolsPeriodic boundary conditionsBoundary value problemHamiltonian (quantum mechanics)Mathematical physicsPhysics Letters A
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The generalized Kadanoff-Baym ansatz with initial correlations

2018

Within the non-equilibrium Green's function (NEGF) formalism, the Generalized Kadanoff-Baym Ansatz (GKBA) has stood out as a computationally cheap method to investigate the dynamics of interacting quantum systems driven out of equilibrium. Current implementations of the NEGF--GKBA, however, suffer from a drawback: real-time simulations require {\em noncorrelated} states as initial states. Consequently, initial correlations must be built up through an adiabatic switching of the interaction before turning on any external field, a procedure that can be numerically highly expensive. In this work, we extend the NEGF--GKBA to allow for {\em correlated} states as initial states. Our scheme makes i…

PhysicsKadanoff-Baym ansatzStrongly Correlated Electrons (cond-mat.str-el)ta114many-body theoryFOS: Physical sciencesNon-equilibrium thermodynamics02 engineering and technologyGreen's functionCondensed Matter::Mesoscopic Systems and Quantum Hall Effect021001 nanoscience & nanotechnology01 natural sciencesSettore FIS/03 - Fisica della MateriaCondensed Matter - Strongly Correlated ElectronsImproved performanceFormalism (philosophy of mathematics)0103 physical sciencesExternal fieldStatistical physicskvanttifysiikka010306 general physics0210 nano-technologyAdiabatic processQuantumAnsatzPhysical Review B
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Aharonov–Bohm/Casher effect in a Kondo ring

2000

The in#uence of a magnetic impurity or ultrasmall quantum dot on the spin and charge persistent currents of a mesoscopic ring is investigated. The system consists of electrons in a one-dimensional ring threaded by spin-dependent Aharonov}Bohm/Casher #uxes, and coupled via an antiferromagnetic exchange interaction to a localized electron. The problem is mapped onto a Kondo model for the even-parity channel plus free electrons in the odd-parity channel. The twisted boundary conditions representing the #uxes couple states of opposite parity unless the twist angles / a satisfy / a "f a p, where f a are integers, with spin index a"C, B. For these special values of / a , the model is solvable by …

PhysicsMesoscopic physicsCondensed matter physicsExchange interactionPersistent currentParity (physics)Condensed Matter::Mesoscopic Systems and Quantum Hall EffectCondensed Matter PhysicsElectronic Optical and Magnetic MaterialsBethe ansatzQuantum mechanicsCondensed Matter::Strongly Correlated ElectronsKondo effectElectrical and Electronic EngineeringKondo modelMagnetic impurityPhysica B: Condensed Matter
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Statistical Mechanics of the Sine-Gordon Equation

1986

We give two fundamental methods for evaluation of classical free energies of all the integrable models admitting soliton solutions; the sine-Gordon equation is one example. Periodic boundary conditions impose integral equations for allowed phonon and soliton momenta. From these, generalized Bethe-Ansatz and functional-integration methods using action-angle variables follow. Results for free energies coincide, and coincide with those that we find by transfer-integral methods. Extension to the quantum case, and quantum Bethe Ansatz, on the lines to be reported elsewhere for the sinh-Gordon equation, is indicated.

PhysicsNonlinear Sciences::Exactly Solvable and Integrable SystemsIntegrable systemDifferential equationGeneral Physics and Astronomysine-Gordon equationStatistical mechanicsSolitonQuantum statistical mechanicsIntegral equationMathematical physicsBethe ansatzPhysical Review Letters
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Statistical mechanics of the NLS models and their avatars

2006

“In Vishnuland what avatar? Or who in Moscow (Leningrad) towards the czar [1]”. The different manifestations (avatars) of the Nonlinear Schrodinger equation (NLS models) are described including both classical and quantum integrable cases. For reasons explained the sinh-Gordon and sine-Gordon models, which can be interpreted as covariant manifestations of the ‘repulsive’ and ‘attractive’ NLS models, respectively, are chosen as generic models for the statistical mechanics. It is shown in the text how the quantum and classical free energies can be calculated by a method of functional integration which uses the classical action-angle variables on the real line with decaying boundary conditions,…

PhysicsPartition function (statistical mechanics)symbols.namesakeNonlinear Sciences::Exactly Solvable and Integrable SystemsIntegrable systemThermodynamic limitsymbolsCovariant transformationStatistical mechanicsQuantumNonlinear Schrödinger equationBethe ansatzMathematical physics
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