Implementation of Memory Centric Scheduling for COTS Multi-Core Real-Time Systems

The demands for high performance computing with a low cost and low power consumption are driving a transition towards multi-core processors in many consumer and industrial applications. However, the adoption of multi-core processors in the domain of real-time systems faces a series of challenges that has been the focus of great research intensity during the last decade. These challenges arise in great part from the non real-time nature of the hardware arbiters that schedule the access to shared resources, such as the main memory. One solution proposed in the literature is called Memory Centric Scheduling, which defines a separate software scheduler for the sections of the tasks that will access the main memory, hence circumventing the low level unpredictable hardware arbiters. Several Memory Centric schedulers and associated theoretical analyses have been proposed, but as far as we know, no actual implementation of the required OS-level underpinnings to support dynamic event-driven Memory Centric Scheduling has been presented before. In this paper we aim to fill this gap, targeting cache based COTS multi-core systems. We will confirm via measurements the main theoretical benefits of Memory Centric Scheduling (e.g. task isolation). Furthermore, we will describe an effective schedulability analysis using concepts from distributed systems

Análisis de la introducción de los números decimales en un libro de texto

El libro de texto constituye uno de los referentes básicos para la organización de un proceso de enseñanza. Consideramos que debe ser objeto de revisión permanente para evaluar su pertinencia disciplinar y didáctica, identificar aspectos potencialmente conflictivos, y promover su adecuación a la labor de enseñanza y aprendizaje. En este artículo presentamos un análisis de una lección de un texto de matemáticas para cuarto curso de primaria, con el propósito de determinar el grado de adecuación del mismo para la introducción de los números decimales en dicho nivel escolar. El análisis de la lección, basado en un referente teórico, construido a partir de resultados de investigaciones sobre la didáctica de los números decimales, permite reflexionar sobre un uso pertinente del libro de texto

Análisis epistémico y cognitivo de tareas en la formación de profesores de matemáticas

En este trabajo proponemos una herramienta de análisis epistémico/cognitivo de tareas que contribuye al desarrollo de dos tipos de conocimiento matemático para la enseñanza: conocimiento especializado del contenido y conocimiento de los estudiantes. Aplicamos la herramienta al análisis de un problema de proporcionalidad y las soluciones dadas al mismo por un grupo de estudiantes de magisterio. Concluimos con la potencial utilidad de estos análisis para la formación de profesores

The Bose–Hubbard model with squeezed dissipation

The stationary properties of the Bose–Hubbard model under squeezed dissipation are investigated. The dissipative model does not possess aU (1) symmetry but conserves parity. We find that 〈a j 〉 = 0 always holds, so no symmetry breaking occurs. Without the onsite repulsion, the linear case is known to be critical. At the critical point the system freezes to an EPR state with infinite two mode entanglement. We show here that the correlations are rapidly destroyed whenever the repulsion is switched on. As we increase the latter, the system approaches a thermal state with an effective temperature defined in terms of the squeezing parameter in the dissipators. We characterize this transition by means of a Gutzwiller ansatz and the Gaussian Hartree–Fock–Bogoliubov approximation

Estudio epistémico del número π: implicaciones didácticas

La realización de un estudio documental epistemológico de la evolución de pi, nos permitió reconstruir un referente global para este número. Concretamente hemos recuperado a lo largo de su construcción científica, tipos de situaciones problemas y sistemas de prácticas en que se pone en juego este objeto. Si bien el punto de partida fue la detección de problemas que hicieran emerger algún significado de pi, interesó estudiar las técnicas, los lenguajes, las entidades conceptuales, proposicionales y argumentativas puestas en juego en cada momento y circunstancia. Los sistemas de prácticas identificados por ese conjunto de objetos permitieron estudiar y describir, desde el punto de vista epistémico, como se configuran los mencionados objetos matemáticos y poner en descubierto la complejidad epistémica de pi. Así, la construcción de un referente global permitió describir tres etapas en las que se ponen de manifiesto que pi va asumiendo diferentes estatus y características, posibilitando dar respuesta a algunos interrogantes vinculados a la enseñanza

The level of recognition of physical symptoms in patients with a major depression episode in the outpatient psychiatric practice in Puerto Rico: An observational study

BACKGROUND: This study was designed to evaluate the psychiatrists' level of recognition of somatic symptoms associated to a major depressive episode (MDE) (DSM-IV-TR criteria) and the impact of those somatic symptoms on the treatment effectiveness. METHODS: This non-interventional study was conducted in 25 medical offices in Puerto Rico from February to December 2003. It had 2 visits separated by 8 weeks. The level of recognition was determined by: the correlation between the physician clinical evaluation and their patients' self-evaluations through different validated instruments using kappa statistics. Chi-square test was used to evaluate the impact of somatic symptoms on treatment antidepressants' effectiveness. RESULTS: All the 145 recruited patients reported the presence of at least one somatic symptom associated with their current MDE. In the two visits covered by the study, a fair agreement between the psychiatrists' and the patients' reports was noted for headache, abdominal pain and upper limb pains (0.4003 ≤ κ ≥ 0.6594). For other painful symptoms and painless somatic symptoms, the Kappa values obtained were non-significant. Slight but significant reductions in depression and painful symptoms severity were observed after 8 weeks of treatment. A proportional relationship between the pain and depression severity was observed (p < 0.0001). CONCLUSION: The study results show that somatic symptoms: are very common in depressed Puerto Rican patients; are significant under-reported by psychiatrists; and have a significant impact on the antidepressant effectiveness

Gentlest ascent dynamics on manifolds defined by adaptively sampled point-clouds

Finding saddle points of dynamical systems is an important problem in practical applications such as the study of rare events of molecular systems. Gentlest ascent dynamics (GAD) is one of a number of algorithms in existence that attempt to find saddle points in dynamical systems. It works by deriving a new dynamical system in which saddle points of the original system become stable equilibria. GAD has been recently generalized to the study of dynamical systems on manifolds (differential algebraic equations) described by equality constraints and given in an extrinsic formulation. In this paper, we present an extension of GAD to manifolds defined by point-clouds, formulated using the intrinsic viewpoint. These point-clouds are adaptively sampled during an iterative process that drives the system from the initial conformation (typically in the neighborhood of a stable equilibrium) to a saddle point. Our method requires the reactant (initial conformation), does not require the explicit constraint equations to be specified, and is purely data-driven

Arundo donax L processing in catalyzed butanol–water media in the scope of lignocellulose biorefineries

Arundo donax L samples, before or after aqueous extraction to remove extractives, were subjected to chemical fractionation in H2SO4-catalyzed mixtures of 1-butanol and water. The partial miscibility of 1-butanol and water at room temperature allowed the separation of the three major feedstock components in separate streams (lignin, accumulated in the 1-butanol-rich phase; hemicellulose-derived products, accumulated in the aqueous acidic phase; and cellulose, present in the solid phase). The effects of selected variables (temperature, catalyst concentration, reaction time and 1-butanol content of the reaction media) on variables measuring the solid recovery yield and the compositions of phases from fractionation were measured. Using water-extracted A. donax L as a substrate, the best operational conditions enabled 93.2% hemicellulose removal and 85.4% delignification with limited cellulose solubilization (15%). The experimental results provided key information to assess the proposed process in the scope of biorefineries.Ministerio de Ciencia e Innovación | Ref. IJC2018-037665Ministerio de Ciencia e Innovación | Ref. PID2020-116717RB-I00Ministerio de Ciencia e Innovación | Ref. RYC2021-031964-

Tipping Points of Evolving Epidemiological Networks: Machine Learning-Assisted, Data-Driven Effective Modeling

We study the tipping point collective dynamics of an adaptive susceptible-infected-susceptible (SIS) epidemiological network in a data-driven, machine learning-assisted manner. We identify a parameter-dependent effective stochastic differential equation (eSDE) in terms of physically meaningful coarse mean-field variables through a deep-learning ResNet architecture inspired by numerical stochastic integrators. We construct an approximate effective bifurcation diagram based on the identified drift term of the eSDE and contrast it with the mean-field SIS model bifurcation diagram. We observe a subcritical Hopf bifurcation in the evolving network's effective SIS dynamics, that causes the tipping point behavior; this takes the form of large amplitude collective oscillations that spontaneously -- yet rarely -- arise from the neighborhood of a (noisy) stationary state. We study the statistics of these rare events both through repeated brute force simulations and by using established mathematical/computational tools exploiting the right-hand-side of the identified SDE. We demonstrate that such a collective SDE can also be identified (and the rare events computations also performed) in terms of data-driven coarse observables, obtained here via manifold learning techniques, in particular Diffusion Maps. The workflow of our study is straightforwardly applicable to other complex dynamics problems exhibiting tipping point dynamics.Comment: 22 pages, 12 figure