Instituto Universitario de Investigación "Carlos I" de Física Teórica y Computacional
http://hdl.handle.net/10481/31014
Tue, 22 Jan 2019 16:05:19 GMT2019-01-22T16:05:19ZConcurrence of form and function in developing networks and its role in synaptic pruning
http://hdl.handle.net/10481/51958
Concurrence of form and function in developing networks and its role in synaptic pruning
Millán Vidal, Ana Paula; Torres, J. J.; Johnson, S.; Marro Borau, Joaquín
A fundamental question in neuroscience is how structure and function of neural systems are
related. We study this interplay by combining a familiar auto-associative neural network with
an evolving mechanism for the birth and death of synapses. A feedback loop then arises
leading to two qualitatively different types of behaviour. In one, the network structure
becomes heterogeneous and dissasortative, and the system displays good memory performance;
furthermore, the structure is optimised for the particular memory patterns stored
during the process. In the other, the structure remains homogeneous and incapable of pattern
retrieval. These findings provide an inspiring picture of brain structure and dynamics that
is compatible with experimental results on early brain development, and may help to explain
synaptic pruning. Other evolving networks—such as those of protein interactions—might
share the basic ingredients for this feedback loop and other questions, and indeed many of
their structural features are as predicted by our model.
http://hdl.handle.net/10481/51958Heisenberg and Entropic Uncertainty Measures for Large-Dimensional Harmonic Systems
http://hdl.handle.net/10481/49123
Heisenberg and Entropic Uncertainty Measures for Large-Dimensional Harmonic Systems
Puertas-Centeno, David; Valero Toranzo, Irene; Sánchez-Dehesa Moreno-Cid, Jesús
The D-dimensional harmonic system (i.e., a particle moving under the action of a quadratic potential) is, together with the hydrogenic system, the main prototype of the physics of multidimensional quantum systems. In this work, we rigorously determine the leading term of the Heisenberg-like and entropy-like uncertainty measures of this system as given by the radial expectation values and the Rényi entropies, respectively, at the limit of large D. The associated multidimensional position-momentum uncertainty relations are discussed, showing that they saturate the corresponding general ones. A conjecture about the Shannon-like uncertainty relation is given, and an interesting phenomenon is observed: the Heisenberg-like and Rényi-entropy-based equality-type uncertainty relations for all of the D-dimensional harmonic oscillator states in the pseudoclassical ( D → ∞ ) limit are the same as the corresponding ones for the hydrogenic systems, despite the so different character of the oscillator and Coulomb potentials.
http://hdl.handle.net/10481/49123On Generalized Stam Inequalities and Fisher–Rényi Complexity Measures
http://hdl.handle.net/10481/48486
On Generalized Stam Inequalities and Fisher–Rényi Complexity Measures
Zozor, Steeve; Puertas-Centeno, David; Sánchez-Dehesa Moreno-Cid, Jesús
Information-theoretic inequalities play a fundamental role in numerous scientific and technological areas (e.g., estimation and communication theories, signal and information processing, quantum physics, …) as they generally express the impossibility to have a complete description of a system via a finite number of information measures. In particular, they gave rise to the design of various quantifiers (statistical complexity measures) of the internal complexity of a (quantum) system. In this paper, we introduce a three-parametric Fisher–Rényi complexity, named ( p , β , λ ) -Fisher–Rényi complexity, based on both a two-parametic extension of the Fisher information and the Rényi entropies of a probability density function ρ characteristic of the system. This complexity measure quantifies the combined balance of the spreading and the gradient contents of ρ , and has the three main properties of a statistical complexity: the invariance under translation and scaling transformations, and a universal bounding from below. The latter is proved by generalizing the Stam inequality, which lowerbounds the product of the Shannon entropy power and the Fisher information of a probability density function. An extension of this inequality was already proposed by Bercher and Lutwak, a particular case of the general one, where the three parameters are linked, allowing to determine the sharp lower bound and the associated probability density with minimal complexity. Using the notion of differential-escort deformation, we are able to determine the sharp bound of the complexity measure even when the three parameters are decoupled (in a certain range). We determine as well the distribution that saturates the inequality: the ( p , β , λ ) -Gaussian distribution, which involves an inverse incomplete beta function. Finally, the complexity measure is calculated for various quantum-mechanical states of the harmonic and hydrogenic systems, which are the two main prototypes of physical systems subject to a central potential.
http://hdl.handle.net/10481/48486Libro de resúmenes de las II Jornadas Científicas del Instituto Carlos I de Física Teórica y Computacional
http://hdl.handle.net/10481/37811
Libro de resúmenes de las II Jornadas Científicas del Instituto Carlos I de Física Teórica y Computacional
Instituto Carlos I de Física Teórica y Computacional
Las Jornadas Científicas del Insituto Carlos I de Física Teórica y Computacional pretenden ser una plataforma de comunicación
e intercambio de ideas entre los miembros que forman el Instituto. En este libro se presentan los resúmenes de
las contribuciones a estas Jornadas. Aparecen en orden cronológico de acuerdo con el programa de las Jornadas, siendo las
contribuciones un reflejo de algunas de las investigaciones que actualmente se realizan en este Instituto de Investigación.
Comité organizador: Elvira Romera Gutiérrez, Miguel Ángel Muñoz Martínez.
http://hdl.handle.net/10481/37811Asymptotic model for shape resonance control of diatomics by intense non-resonant light
http://hdl.handle.net/10481/36641
Asymptotic model for shape resonance control of diatomics by intense non-resonant light
Crubellier, Anne; González-Férez, Rosario; Koch, Christiane P.; Luc-Koening, Eliane
Non-resonant light interacting with diatomics via the polarizability anisotropy couples different rotational states and may lead to strong hybridization of the motion. The modification of shape resonances and low-energy scattering states due to this interaction can be fully captured by an asymptotic model, based on the long-range properties of the scattering (Crubellier et al 2015 New J. Phys. 17 045020). Remarkably, the properties of the field-dressed shape resonances in this asymptotic multi-channel description are found to be approximately linear in the field intensity up to fairly large intensity. This suggests a perturbative single-channel approach to be sufficient to study the control of such resonances by the non-resonant field. The multi-channel results furthermore indicate the dependence on field intensity to present, at least approximately, universal characteristics. Here we combine the nodal line technique to solve the asymptotic Schrödinger equation with perturbation theory. Comparing our single channel results to those obtained with the full interaction potential, we find nodal lines depending only on the field-free scattering length of the diatom to yield an approximate but universal description of the field-dressed molecule, confirming universal behavior.
http://hdl.handle.net/10481/36641