Non-monotonic flow variations in a TASEP-based traffic model featuring cars searching for parking

The Totally Asymmetric Simple Exclusion Process (TASEP) is a paradigm of out-of-equilibrium Statistical Physics that serves as a simplistic model for one-way vehicular traffic. Since traffic is perturbed by cars cruising for parking in many metropolises, we introduce a variant of TASEP, dubbed SFP, in which particles are initially cruising at a slower speed and aiming to park on one of the sites adjacent to the main road, described by a unidimensional lattice. After parking, they pull out at a finite rate and move at a normal speed. We show that this model, which breaks many of the conservation rules applicable in other TASEP variants, exhibits singular features, in particular non-monotonic variations of the steady-state current with the injection rate and re-entrant transitions in the phase diagram, for some range of parameters. These features are robust to variations in the update rule and the boundary conditions.Neither the slow speed of cruising cars nor the perturbation of the flow due to pull-out maneuvers, taken in isolation, can rationalize these observations. Instead, they originate in a cramming (or `paper jam') effect which results from the coupling of these mechanisms: injecting too many cars into the system saturates the first sites of the road, which prevents parked cars from pulling out, thus forcing cruising cars to travel farther along the road.These strong discrepancies with even the qualitative trends of the baseline TASEP model highlight the importance of considering the effect of perturbations on traffic

Numerical evidences of a universal critical behavior of 2D and 3D random quantum clock and Potts models

The random quantum $q$-state clock and Potts models are studied in 2 and 3 dimensions. The existence of Griffiths phases is tested in the 2D case with $q=6$ by sampling the integrated probability distribution of local susceptibilities of the equivalent McCoy-Wu 3D classical modelswith Monte Carlo simulations. No Griffiths phase is found for the clock model. In contrast, numerical evidences of the existence of Griffiths phases in the random Potts model are given and the Finite Size effects are analyzed. The critical point of the random quantum clock model is then studied by Strong-Disorder Renormalization Group. Despite a chaotic behavior of the Renormalization-Group flow at weak disorder, evidences are given that this critical behavior is governed by the same Infinite-Disorder Fixed Point as the Potts model, independently from the number of states $q$

Etude numérique du point critique de systèmes quantiques de spin désordonnés en dimensions élevées

Several random quantum spin models have been numerically studied in dimension $D>1$ by Strong Disorder Renormalisation Group (SDRG). We have implemented an efficient algorithm to be able to consider a system with up to a billion spins independently of its spatial dimension. Critical properties of the $2D$ and $3D$ random quantum Potts model with $q=2,3,5,10,20$ and $50$ states are shown to be governed by an infinite disorder fixed point. We have computed the correlation-length exponent $u$, the magnetization exponent $d_f$ and the energy gap exponent $psi$. Using finite-size scaling and taking into account finite-size corrections, critical properties of the Potts model are shown to be $q$-independent. Random quantum Clock models with $q=2,3,5,8$ and $10$ states have been also studied in $2D$ and $3D$. A minimum amount of initial disorder strength is required to flow to an infinite disorder fixed point. Despite large error bars on $psi$ exponent, our estimates for the critical exponents $u$ and $psi$ for all $q$ are compatible with those of the random transverse-field Ising model. Our estimates for the critical exponent $d_f$ are incompatible within error bar but very close. Lastly, the tricritical point of the random quantum Ashkin-Teller model has been studied in dimension two and three. We have shown that the correlation-length exponent associated with one of the two unstable directions does not belong to the university class of the random transverse-field Ising model.Nous avons étudié numériquement plusieurs modèles de spins quantiques désordonnés en dimensions $D>1$ par le groupe de renormalisation en désordre fort (SDRG). Pour cela, nous avons implémenté un algorithme permettant de considérer des systèmes contenant de l'ordre d'un million de spins indépendamment de la dimension du réseau. Nous avons montré que les propriétés critiques du modèle de Potts quantique désordonné à $q=2,3,5,10,20$ et $50$ états en dimensions $D=2$ et $D=3$ sont gouvernées par un point fixe de désordre infini. Nous avons estimé les exposants critiques de la longueur de corrélation $u$, de l'aimantation $d_f$ et du gap d'énergie $psi$. En exploitant les effets de taille finie et en prenant en compte les corrections, nous avons conclut que les propriétés critiques du modèle de Potts sont indépendantes du nombre d'états $q$. Nous avons également étudié le modèle d'horloge quantique désordonné à $q=2,3,5,8$ et $10$ états en dimensions $D=2$ et $D=3$. L'importance du désordre initial a été mis en évidence pour pouvoir atteindre un point critique de désordre infini. Bien que les incertitudes sur $psi$ soient grandes, nos estimations des exposants $u$ et $psi$ sont compatibles pour tout $q$ avec ceux du modèle d'Ising quantique désordonné. Les estimations de l'exposant $d_f$ sont incompatibles dans les barres d'erreur mais néanmoins très proches. Enfin, nous avons étudié le point tricritique du modèle d'Ashkin-Teller quantique désordonné en dimensions $D=2$ et $D=3$. Nous avons montré que l'exposant de la longueur de corrélation dans une des directions instables n'appartient pas à la classe d'universalité du modèle d'Ising quantique désordonné

Numerical study of the critical point of disordered quantum spin systems in high dimensions

Nous avons étudié numériquement plusieurs modèles de spins quantiques désordonnés en dimensions D>1 par le groupe de renormalisation en désordre fort (SDRG). Pour cela, nous avons implémenté un algorithme permettant de considérer des systèmes contenant de l'ordre d'un million de spins indépendamment de la dimension du réseau. Nous avons montré que les propriétés critiques du modèle de Potts quantique désordonné à q=2,3,5,10,20 et 50 états en dimensions D=2 et D=3 sont gouvernées par un point fixe de désordre infini. Nous avons estimé les exposants critiques de la longueur de corrélation u, de l'aimantation d_f et du gap d'énergie psi. En exploitant les effets de taille finie et en prenant en compte les corrections, nous avons conclut que les propriétés critiques du modèle de Potts sont indépendantes du nombre d'états q. Nous avons également étudié le modèle d'horloge quantique désordonné à q=2,3,5,8 et 10 états en dimensions D=2 et D=3. L'importance du désordre initial a été mis en évidence pour pouvoir atteindre un point critique de désordre infini. Bien que les incertitudes sur psi soient grandes, nos estimations des exposants u et psi sont compatibles pour tout q avec ceux du modèle d'Ising quantique désordonné. Les estimations de l'exposant d_f sont incompatibles dans les barres d'erreur mais néanmoins très proches. Enfin, nous avons étudié le point tricritique du modèle d'Ashkin-Teller quantique désordonné en dimensions D=2 et D=3. Nous avons montré que l'exposant de la longueur de corrélation dans une des directions instables n'appartient pas à la classe d'universalité du modèle d'Ising quantique désordonné.Several random quantum spin models have been numerically studied in dimension D>1 by Strong Disorder Renormalisation Group (SDRG). We have implemented an efficient algorithm to be able to consider a system with up to a billion spins independently of its spatial dimension. Critical properties of the 2D and 3D random quantum Potts model with q=2,3,5,10,20 and 50 states are shown to be governed by an infinite disorder fixed point. We have computed the correlation-length exponent u, the magnetization exponent d_f and the energy gap exponent psi. Using finite-size scaling and taking into account finite-size corrections, critical properties of the Potts model are shown to be q-independent. Random quantum Clock models with q=2,3,5,8 and 10 states have been also studied in 2D and 3D. A minimum amount of initial disorder strength is required to flow to an infinite disorder fixed point. Despite large error bars on psi exponent, our estimates for the critical exponents u and psi for all q are compatible with those of the random transverse-field Ising model. Our estimates for the critical exponent d_f are incompatible within error bar but very close. Lastly, the tricritical point of the random quantum Ashkin-Teller model has been studied in dimension two and three. We have shown that the correlation-length exponent associated with one of the two unstable directions does not belong to the university class of the random transverse-field Ising model

Numerical evidence of superuniversality of the 2D and 3D random quantum Potts models

International audienceThe random $q$-state quantum Potts model is studied on hypercubic lattices in dimensions 2 and 3 using the numerical implementation of the Strong Disorder Renormalization Group introduced by Kovacs and Iglói [Phys. Rev. B 82, 054437 (2010)]. Critical exponents $\nu$, $d_f$ and $\psi$ at the Infinite Disorder Fixed Point are estimated by Finite-Size Scaling for several numbers of states $q$ between 2 and 50. When scaling corrections are not taken into account, the estimates of both $d_f$ and $\psi$ systematically increase with $q$. It is shown however that $q$-dependent scaling corrections are present and that the exponents are compatible within error bars, or close to each other, when these corrections are taking into account. This provides evidence of the existence of a superuniversality of all 2D and 3D random Potts models

Iron loaded EMT nanosized zeolite with high affinity towards CO 2 and NO

CERVOXY COLLInternational audienceThe preparation of iron-loaded nanosized zeolite with EMT-type structure (Fe-EMT) is reported. The sorption capacity of the Fe-EMT zeolite crystals for NO and CO2 is evaluated. The application of Fe-EMT zeolite as a gas delivery system with high capacity for CO2 and NO in biomedicine is considered. Therefore the toxicity of the pure EMT and Fe-EMT zeolite nanocrystals is studied. Primary culture of astrocytes was exposed to zeolite nanocrystals. In addition, two human cell lines, U87-MG glioblastoma and HEK-293T were used. Cells were exposed to zeolites nanocrystals with concentrations of 50, 100 and 400 μg/ml for 24 h and 48 h. Cytotoxicity was assessed by a cell viability assay and no alteration of cell viability exposed to zeolite nanoparticles was observed

A new strategy for treatment of glioblastoma via reoxygenation using zeolites nanocrystals

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Copper exchanged FAU nanozeolite as non-toxic nitric oxide and carbon dioxide gas carrier

CERVOXY COLLInternational audienc

Copper exchanged FAU nanozeolite as non-toxic nitric oxide and carbon dioxide gas carrier

CERVOXY COLLInternational audienc