Localization transition induced by learning in random searches

We solve an adaptive search model where a random walker or L\'evy flight stochastically resets to previously visited sites on a $d$-dimensional lattice containing one trapping site. Due to reinforcement, a phase transition occurs when the resetting rate crosses a threshold above which non-diffusive stationary states emerge, localized around the inhomogeneity. The threshold depends on the trapping strength and on the walker's return probability in the memoryless case. The transition belongs to the same class as the self-consistent theory of Anderson localization. These results show that similarly to many living organisms and unlike the well-studied Markovian walks, non-Markov movement processes can allow agents to learn about their environment and promise to bring adaptive solutions in search tasks.Comment: 5 pages, 5 figures + 4 pages of Supplemental Information. Accepted in Physical Review Letter

Frequency and voltage partitioning in presence of renewable energy resources for power system (example: North Chile power network)

This paper investigates techniques for frequency and voltage partitioning of power network based on the graph-theory. These methods divide the power system into distinguished regions to avoid the spread of disturbances and to minimize the interaction between these regions for frequency and voltage control of power system. In case of required active and reactive power for improving the performance of the power system, control can be performed regionally instead of a centralized controller. In this paper, renewable energy sources are connected to the power network to verify the effect of these sources on the power systems partitioning and performance. The number of regions is found based on the frequency sensitivity for frequency partitioning and bus voltage for voltage partitioning to disturbances being applied to loads in each region. The methodology is applied to the north part of Chile power network. The results show the performance and ability of graph frequency and voltage partitioning algorithm to divide large scale power systems to smaller regions for applying decentralized controllers.Peer ReviewedPostprint (published version

Bound states in the continuum: localization of Dirac-like fermions

We report the formation of bound states in the continuum for Dirac-like fermions in structures composed by a trilayer graphene flake connected to nanoribbon leads. The existence of this kind of localized states can be proved by combining local density of states and electronic conductance calculations. By applying a gate voltage, the bound states couple to the continuum, yielding a maximum in the electronic transmission. This feature can be exploited to identify bound states in the continuum in graphene-based structures.Comment: 7 pages, 5 figure

Análisis de una propuesta de evaluación en relación con la estructura conceptual de la proporcionalidad

La presente propuesta es una aproximación reflexiva y critica de las prácticas evaluativas que se vienen desarrollando en la enseñanza básica y media en las instituciones de carácter privado de la ciudad de Cali, sustentada desde nuestra propia experiencia como docentes en ejercicio y estudiantes de último semestre en Licenciatura de Matemáticas y Física de la Universidad del Valle, y apoyada en el análisis de unas actividades piloto de intervención y evaluación matemática, en torno a diferentes nociones y conceptos relacionados con la estructura conceptual del tópico de proporción y proporcionalidad en los grados de séptimo de educación básica y décimo de educación media que se realizaron a fin de plantear una serie de interrogantes cruciales en torno a la evaluación, dado su carácter organizador, dinamizador y potencializador del currículo. Esta propuesta se apoyará en el marco metodológico de los organizadores del currículo, donde la evaluación es un eje fundamental en el análisis didáctico que permite la articulación y organización de un currículo significativo para los intereses de los educandos

Radiative decay Z_H-> \gamma A_H in the little Higgs model with T-parity

In the little Higgs model with T-parity (LHTM), the only tree-level kinematically allowed two-body decay of the Z_H boson is Z_H-> A_H H and thus one-loop induced two-body decays may have a significant rate. We study the Z_H-> \gamma A_H decay, which is induced at the one-loop level by a fermion triangle and is interesting as it depends on the mechanism of anomaly cancellation of the model. All the relevant two- and three-body decays of the Z_H gauge boson arising at the tree-level are also calculated. We consider a small region of the parameter space where the scale of the symmetry breaking f is still allowed to be as low as 500 GeV by electroweak precision data. We first analyze the scenario of a Higgs boson with a mass of 120 GeV. We found that the Z_H->\gamma A_H branching ratio can be of the order of a tree-level three-body decay and may be at the reach of detection at the LHC for f close to 500 GeV, but it may be difficult to detect for f=1 TeV. There is also an scenario where the Higgs boson has an intermediate mass such that the Z_H-> A_H H decay is closed, the Z_H-> \gamma A_H gets considerably enhanced and the chances of detection get a large boost.Comment: 19 pages, 9 figures, 2 table

Patrimonio minero-metalúrgico de Rodalquilar: Metodología de catalogación y resultados

Para estudiar y conservar el Patrimonio, es necesario desarrollar una metodología para la catalogación y valoración de los elementos patrimoniales. Un caso real catalogación de una antigua zona minera; Rodalquilar (Almería) en el Sudeste de España, es el objetivo del presente trabajo

Momentum and energy preserving integrators for nonholonomic dynamics

In this paper, we propose a geometric integrator for nonholonomic mechanical systems. It can be applied to discrete Lagrangian systems specified through a discrete Lagrangian defined on QxQ, where Q is the configuration manifold, and a (generally nonintegrable) distribution in TQ. In the proposed method, a discretization of the constraints is not required. We show that the method preserves the discrete nonholonomic momentum map, and also that the nonholonomic constraints are preserved in average. We study in particular the case where Q has a Lie group structure and the discrete Lagrangian and/or nonholonomic constraints have various invariance properties, and show that the method is also energy-preserving in some important cases.Comment: 18 pages, 6 figures; v2: example and figures added, minor correction to example 2; v3: added section on nonholonomic Stoermer-Verlet metho

Hysteresis of nanocylinders with Dzyaloshinskii-Moriya interaction

The potential for application of magnetic skyrmions in high density storage devices provides a strong drive to investigate and exploit their stability and manipulability. Through a three-dimensional micromagnetic hysteresis study, we investigate the question of existence of skyrmions in cylindrical nanostructures of variable thickness. We quantify the applied field and thickness dependence of skyrmion states, and show that these states can be accessed through relevant practical hysteresis loop measurement protocols. As skyrmionic states have yet to be observed experimentally in confined helimagnetic geometries, our work opens prospects for developing viable hysteresis process-based methodologies to access and observe skyrmionic states.Comment: 4 pages, 2 figure

Continuidad del cuidado: adulto mayor con diabetes tipo 2 y su cuidador

ResumenObjetivoAplicar la continuidad del cuidado en la persona con diabetes tipo 2 (DT2) y su cuidador, posterior al egreso hospitalario a través de intervenciones de enfermería domiciliaria que contribuyan a mejorar el estilo de vida.MétodoSe trata un proceso de enfermería a un adulto mayor con DT2 y a su cuidador primario, mediante una valoración de enfermería inicial y la medición del conocimiento de la enfermedad a través del Cuestionario de Conocimiento en Diabetes-24 y estilo de vida, con el Instrumento para Medir el Estilo de Vida en Diabéticos. La identificación de necesidades con la taxonomía NANDA permitió intervenciones de tipo informacional, de relación y gestión basadas en la Clasificación de Intervenciones de Enfermería para la continuidad del cuidado. Las intervenciones educativas fueron ejecutadas en sesiones periódicas, bajo consentimiento informado de los participantes, a través de una metodología interactiva. La efectividad fue evaluada con una valoración final de la persona con DT2 y cuidador.ResultadosSe observó un incremento del nivel de conocimientos de la enfermedad y una mejora en el estilo de vida, de la persona con DT2 y su cuidador, en los dominios: nutrición, actividad física, emociones y adherencia terapéutica.ConclusiónLa continuidad del cuidado en la persona con DT2 y su cuidador es una herramienta indispensable para mejorar el estilo de vida y nivel de conocimientos, disminuir el riesgo de complicaciones y evitar reingresos hospitalarios.AbstractObjectiveTo establish the continuity care on persons suffering from diabetes type 2 (DT2) and their caregiver following hospital discharge, through home-visit interventions which can contribute to the improvement of lifestyles.MethodThe nursing process was performed on a patient with DT2 and the corresponding primary caregiver through a nursing assessment which included the use of the 24-Diabetes Knowledge Questionnaire and the Instrument to Measure Lifestyles in patients with Diabetes Type 2. The identification of needs through the NANDA taxonomy allowed informational, relational and managerial interventions based on the Nursing Interventions Classification. The educational interventions were performed during periodic sessions under the informed consent of the participants and through an interactive methodology. The effectiveness was assessed through a final evaluation of the patient and corresponding caregiver.ResultsAn increment in the level of knowledge of the illness and an improvement in the lifestyle of the person with DT2 and the corresponding caregiver, in the nutrition, physical activity, emotions, and therapeutic adherence domains were observed.ConclusionThe continuity care on the person with DT2 is a critical tool to improve the lifestyle and level of knowledge, and to reduce the risk of complications and hospital re-entries