On the Dynamics of Induced Maps on the Space of Probability Measures

For the generic continuous map and for the generic homeomorphism of the Cantor space, we study the dynamics of the induced map on the space of probability measures, with emphasis on the notions of Li-Yorke chaos, topological entropy, equicontinuity, chain continuity, chain mixing, shadowing and recurrence. We also establish some results concerning induced maps that hold on arbitrary compact metric spaces.Comment: 23 page

C4.5: um recurso para geração de árvores de decisão.

O Sistema de Indução C4.5. Requerimentos-chave para a utilização do software. Um exemplo ilustrativo. Algumas dicas de uso.bitstream/CNPTIA/9200/1/INSTRTECNICAS7int.pdfAcesso em: 30 maio 2008

Emergence of Hierarchy on a Network of Complementary Agents

Complementarity is one of the main features underlying the interactions in biological and biochemical systems. Inspired by those systems we propose a model for the dynamical evolution of a system composed by agents that interact due to their complementary attributes rather than their similarities. Each agent is represented by a bit-string and has an activity associated to it; the coupling among complementary peers depends on their activity. The connectivity of the system changes in time respecting the constraint of complementarity. We observe the formation of a network of active agents whose stability depends on the rate at which activity diffuses in the system. The model exhibits a non-equilibrium phase transition between the ordered phase, where a stable network is generated, and a disordered phase characterized by the absence of correlation among the agents. The ordered phase exhibits multi-modal distributions of connectivity and activity, indicating a hierarchy of interaction among different populations characterized by different degrees of activity. This model may be used to study the hierarchy observed in social organizations as well as in business and other networks.Comment: 13 pages, 4 figures, submitte

Rate analysis for a hybrid quantum repeater

We present a detailed rate analysis for a hybrid quantum repeater assuming perfect memories and using optimal probabilistic entanglement generation and deterministic swapping routines. The hybrid quantum repeater protocol is based on atomic qubit-entanglement distribution through optical coherent-state communication. An exact, analytical formula for the rates of entanglement generation in quantum repeaters is derived, including a study on the impacts of entanglement purification and multiplexing strategies. More specifically, we consider scenarios with as little purification as possible and we show that for sufficiently low local losses, such purifications are still more powerful than multiplexing. In a possible experimental scenario, our hybrid system can create near-maximally entangled (F = 0.98) pairs over a distance of 1280 km at rates of the order of 100 Hz

Probing quantum fluctuation theorems in engineered reservoirs

Fluctuation Theorems are central in stochastic thermodynamics, as they allow for quantifying the irreversibility of single trajectories. Although they have been experimentally checked in the classical regime, a practical demonstration in the framework of quantum open systems is still to come. Here we propose a realistic platform to probe fluctuation theorems in the quantum regime. It is based on an effective two-level system coupled to an engineered reservoir, that enables the detection of the photons emitted and absorbed by the system. When the system is coherently driven, a measurable quantum component in the entropy production is evidenced. We quantify the error due to photon detection inefficiency, and show that the missing information can be efficiently corrected, based solely on the detected events. Our findings provide new insights into how the quantum character of a physical system impacts its thermodynamic evolution.Comment: 9 pages, 4 figure

Characterizing neuromorphologic alterations with additive shape functionals

The complexity of a neuronal cell shape is known to be related to its function. Specifically, among other indicators, a decreased complexity in the dendritic trees of cortical pyramidal neurons has been associated with mental retardation. In this paper we develop a procedure to address the characterization of morphological changes induced in cultured neurons by over-expressing a gene involved in mental retardation. Measures associated with the multiscale connectivity, an additive image functional, are found to give a reasonable separation criterion between two categories of cells. One category consists of a control group and two transfected groups of neurons, and the other, a class of cat ganglionary cells. The reported framework also identified a trend towards lower complexity in one of the transfected groups. Such results establish the suggested measures as an effective descriptors of cell shape

Survival-extinction phase transition in a bit-string population with mutation

A bit-string model for the evolution of a population of haploid organisms, subject to competition, reproduction with mutation and selection is studied, using mean field theory and Monte Carlo simulations. We show that, depending on environmental flexibility and genetic variability, the model exhibits a phase transtion between extinction and survival. The mean-field theory describes the infinite-size limit, while simulations are used to study quasi-stationary properties.Comment: 11 pages, 5 figure

Entanglement properties of optical coherent states under amplitude damping

Through concurrence, we characterize the entanglement properties of optical coherent-state qubits subject to an amplitude damping channel. We investigate the distillation capabilities of known error correcting codes and obtain upper bounds on the entanglement depending on the non-orthogonality of the coherent states and the channel damping parameter. This work provides a first, full quantitative analysis of these photon-loss codes which are naturally reminiscent of the standard qubit codes against Pauli errors.Comment: 7 pages, 6 figures. Revised version with small corrections; main results remain unaltere

The Portuguese Formal Social Support for Autonomy and Dependence in Pain Inventory (FSSADI_PAIN): A preliminary validation study.

WOS:000326693900009 (Nº de Acesso Web of Science)Objectives. Development and preliminary validation of a Portuguese measure of perceived Formal Social Support for Autonomy and Dependence in Pain (FSSADI_PAIN). Methods. One hundred and fifty-one older adults (88.1% women), between 56 and 94 years of age (M = 75.41; SD = 9.11), who attended one of the following institutions – day care centre (33.1%), nursing home (36.4%) and senior university (30.5%) – were recruited for this study. Along with the FSSADI_PAIN, participants filled out the Portuguese versions of the Brief Pain Inventory (Azevedo et al., 2007, Dor, 15, 6) and the Social Support Scale of Medical Outcomes Survey (Pais-Ribeiro & Ponte, 2009, Psicologia, Saude & Doença, 10, 163). Results. The factorial structure reflected the functions of perceived promotion of (1) dependence and (2) autonomy, showing good internal consistency (a > .70) and sensitivity indices. The FSSADI_PAIN showed good content, discriminant and criterion validity; it differentiated the perceptions of promotion of dependence/autonomy according to individual’s pain severity and disability, as well as the type of institution. Conclusions. These preliminary findings suggest that the FSSADI_PAIN is an innovative and promising measure of perceived formal social support adapted to pain-related context