On the propagation of the highest energy cosmic ray nuclei

We study the propagation of ultra-high energy cosmic ray nuclei through the background of cosmic microwave and intergalactic infrared photons, using recent re-estimates for the density of the last ones. We perform a detailed Monte Carlo simulation to follow the disintegration histories of nuclei starting as Fe and reaching the Earth from extragalactic sources. We obtain the maximum energies of the arriving nuclear fragments as well as the mass composition as a function of the distance traveled. Cosmic rays with energies in excess of $2\times 10^{20}$ eV cannot originate from Fe nuclei produced in sources beyond 10 Mpc.Comment: 8 page

On the disintegration of cosmic ray nuclei by solar photons

We discuss in detail the possibility of observing pairs of simultaneous parallel air showers produced by the fragments of cosmic ray nuclei which disintegrated in collisions with solar photons. We consider scenarios with different cosmic ray compositions, exploring the predicted rates for existing and planned detectors and looking for methods to extract information on the initial composition from the characteristics of the signal. In particular, we find that fluorescence detectors, such as HiRes or the Telescope Array, due to their low threshold ($\sim 10^{17}$ eV) and large area ($\sim 10^4 km^2$) may observe several events per year if cosmic rays at those energies are indeed heavy nuclei. The possibility of exploiting the angular orientation of the plane containing the two showers to further constrain the cosmic ray composition is also discussed.Comment: 15 page

Fault-tolerant control under controller-driven sampling using virtual actuator strategy

We present a new output feedback fault tolerant control strategy for continuous-time linear systems. The strategy combines a digital nominal controller under controller-driven (varying) sampling with virtual-actuator (VA)-based controller reconfiguration to compensate for actuator faults. In the proposed scheme, the controller controls both the plant and the sampling period, and performs controller reconfiguration by engaging in the loop the VA adapted to the diagnosed fault. The VA also operates under controller-driven sampling. Two independent objectives are considered: (a) closed-loop stability with setpoint tracking and (b) controller reconfiguration under faults. Our main contribution is to extend an existing VA-based controller reconfiguration strategy to systems under controller-driven sampling in such a way that if objective (a) is possible under controller-driven sampling (without VA) and objective (b) is possible under uniform sampling (without controller-driven sampling), then closed-loop stability and setpoint tracking will be preserved under both healthy and faulty operation for all possible sampling rate evolutions that may be selected by the controller

Ameloblastoma.

Tesis (Cirujano Dentista, Patología Oral)La presente revisión bibliográfica involucra el estudio de un Tumor Odontogénico poco común, pero de gran importancia, denominado Ameloblastoma, no obstante la escasa cantidad de casos que ocurren a nivel mundial y por lo mismo la poca información a nivel de las actualizaciones respecto de este tema que probablemente posea el Odontólogo General, lo que nos motiva a masificar el conocimiento adquirido por este medio y por una futura publicación en las revistas odontológicas de circulación nacional, colaborando de esta manera a la actualización del conocimiento de nuestros colegas y a su vez facilitando el diagnóstico que ellos puedan tener en sus respectivos pacientes sobre este tipo de patología. El Ameloblastoma es un tumor localmente invasivo que la mayoría de las veces tiene un curso benigno (1). Las metástasis son raras y se asocian a pacientes que han sido sometidos a tratamientos quirúrgicos múltiples o extensos de sus lesiones (2). Se conoce hace muchos años y se lo ha estudiado desde principios del siglo XIX. En su comportamiento clínico representa un crecimiento local persistente en el área maxilofacial con capacidad de provocar una deformidad notable antes de causar debilitamiento grave en las estructuras que involucra (3). Se describen cuatro tipos clínico-radiográficos: convencional, sólido, multiquístico o común (86% de todos los casos), desmoplastico, uniquístico (13% de los casos) y periférico (extraóseo 1% de los casos) (1 )(2), con diversos tipos histológicos que describiremos más adelante y una contraparte maligna denominado Ameloblastoma maligno; este último de excepcional rareza. los Ameloblastomas son tumores de origen epitelial que pueden surgir de diversas estructuras que se forman durante la odontogénesis, así como de entidades patológicas de la cavidad oral, es por este motivo que se hace indispensable y necesario que abordemos el tema desde el punto de vista global y así, comprender desde el punto de vista anátomo-embriológico la ubicación, desarrollo y comportamiento biológico de las posibles etiologías que lo involucrarían, (debido a que hasta el día de hoy no se conoce..

Hysteretic nonequilibrium Ising-Bloch transition

We show that a parametrically driven cubic-quintic complex Ginzburg-Landau equation exhibits a hysteretic nonequilibrium Ising-Bloch transition for large enough quintic nonlinearity. These results help to understand the recent experimental observation of this pheomenon [A. Esteban-Martin et al., Phys. Rev. Lett. 94, 223903 (2005)].Comment: 3 pages + six figure

A physics-based life prediction methodology for thermal barrier coating systems

A novel mechanistic approach is proposed for the prediction of the life of thermal barrier coating (TBC) systems. The life prediction methodology is based on a criterion linked directly to the dominant failure mechanism. It relies on a statistical treatment of the TBC's morphological characteristics, non-destructive stress measurements and on a continuum mechanics framework to quantify the stresses that promote the nucleation and growth of microcracks within the TBC. The last of these accounts for the effects of TBC constituents' elasto-visco-plastic properties, the stiffening of the ceramic due to sintering and the oxidation at the interface between the thermally insulating yttria stabilized zirconia (YSZ) layer and the metallic bond coat. The mechanistic approach is used to investigate the effects on TBC life of the properties and morphology of the top YSZ coating, metallic low-pressure plasma sprayed bond coat and the thermally grown oxide. Its calibration is based on TBC damage inferred from non-destructive fluorescence measurements using piezo-spectroscopy and on the numerically predicted local TBC stresses responsible for the initiation of such damage. The potential applicability of the methodology to other types of TBC coatings and thermal loading conditions is also discussed

Spreading of thin films assisted by thermal fluctuations

We study the spreading of viscous drops on a solid substrate, taking into account the effects of thermal fluctuations in the fluid momentum. A nonlinear stochastic lubrication equation is derived, and studied using numerical simulations and scaling analysis. We show that asymptotically spreading drops admit self-similar shapes, whose average radii can increase at rates much faster than these predicted by Tanner's law. We discuss the physical realizability of our results for thin molecular and complex fluid films, and predict that such phenomenon can in principal be observed in various flow geometries.Comment: 5 pages, 3 figure

Scaling laws of strategic behaviour and size heterogeneity in agent dynamics

The dynamics of many socioeconomic systems is determined by the decision making process of agents. The decision process depends on agent's characteristics, such as preferences, risk aversion, behavioral biases, etc.. In addition, in some systems the size of agents can be highly heterogeneous leading to very different impacts of agents on the system dynamics. The large size of some agents poses challenging problems to agents who want to control their impact, either by forcing the system in a given direction or by hiding their intentionality. Here we consider the financial market as a model system, and we study empirically how agents strategically adjust the properties of large orders in order to meet their preference and minimize their impact. We quantify this strategic behavior by detecting scaling relations of allometric nature between the variables characterizing the trading activity of different institutions. We observe power law distributions in the investment time horizon, in the number of transactions needed to execute a large order and in the traded value exchanged by large institutions and we show that heterogeneity of agents is a key ingredient for the emergence of some aggregate properties characterizing this complex system.Comment: 6 pages, 3 figure