Short-range stationary patterns and long-range disorder in an evolution equation for one-dimensional interfaces

A novel local evolution equation for one-dimensional interfaces is derived in the context of erosion by ion beam sputtering. We present numerical simulations of this equation which show interrupted coarsening in which an ordered cell pattern develops with constant wavelength and amplitude at intermediate distances, while the profile is disordered and rough at larger distances. Moreover, for a wide range of parameters the lateral extent of ordered domains ranges up to tens of cells. This behavior is new in the context of dynamics of surfaces or interfaces with morphological instabilities. We also provide analytical estimates for the stationary pattern wavelength and mean growth velocity

A single-world consistent interpretation of quantum mechanics from fundamental time and length uncertainties

Within ordinary ---unitary--- quantum mechanics there exist global protocols that allow to verify that no definite event ---an outcome to which a probability can be associated--- occurs. Instead, states that start in a coherent superposition over possible outcomes always remain as a superposition. We show that, when taking into account fundamental errors in measuring length and time intervals, that have been put forward as a consequence of a conjunction of quantum mechanical and general relativity arguments, there are instances in which such global protocols no longer allow to distinguish whether the state is in a superposition or not. All predictions become identical as if one of the outcomes occurs, with probability determined by the state. We use this as a criteria to define events, as put forward in the Montevideo Interpretation of Quantum Mechanics. We analyze in detail the occurrence of events in the paradigmatic case of a particle in a superposition of two different locations. We argue that our approach provides a consistent (C) single-world (S) picture of the universe, thus allowing an economical way out of the limitations imposed by a recent theorem by Frauchiger and Renner showing that having a self-consistent single-world description of the universe is incompatible with quantum theory. In fact, the main observation of this paper may be stated as follows: If quantum mechanics is extended to include gravitational effects to a QG theory, then QG, S, and C are satisfied.Comment: thoughts and comments more than welcom

Heavy quark mass effects in parton-to-kaon hadronization probabilities

We examine the relevance of the heavy quarks masses in the perturbative QCD description of hard interactions where charged kaons are produced in the final state. We extract a set of parton-to-kaon hadronization probabilities from a next to leading order QCD global analysis where a general mass variable flavor number scheme accounting for mass effects is implemented. We compare the results with those obtained in the massless approximation and also with those found in the case of final state pions. At variance with the very significant improvement found for the much more precise pion fragmentation phenomenology, the heavy quark mass dependent scheme improves mildly the overall description of current kaon production data. Nevertheless, we find a noticeable reduction in the charm-to-kaon hadronization probability.Fil: Epele, Manuel. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Física de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Física de Buenos Aires; ArgentinaFil: García Canal, Carlos Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Física de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Física de Buenos Aires; ArgentinaFil: Sassot, Rodolfo. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Física de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Física de Buenos Aires; Argentin

Non-linear ripple dynamics on amorphous surfaces patterned by ion-beam sputtering

Erosion by ion-beam sputtering (IBS) of amorphous targets at off-normal incidence frequently produces a (nanometric) rippled surface pattern, strongly resembling macroscopic ripples on aeolian sand dunes. Suitable generalization of continuum descriptions of the latter allows us to describe theoretically for the first time the main nonlinear features of ripple dynamics by IBS, namely, wavelength coarsening and non-uniform propagation velocity, that agree with similar results in experiments and discrete models. These properties are seen to be the anisotropic counterparts of in-plane ordering and (interrupted) pattern coarsening in IBS experiments on rotating substrates and at normal incidence.Comment: 5 pages, 3 figure

Ingeniería concurrente y tecnologías de la información

La ingeniería concurrente (CE por sus siglas en inglés) es un enfoque para la manufactura que permite el diseño y desarrollo simultáneo de productos, procesos y actividades de apoyo. Aunque éste no es un concepto nuevo, ha recibido recientemente cierto empuje de tecnologías de la información como el Internet o algunas técnicas de Inteligencia Artificial. Específicamente, el uso de agentes de software y lenguajes para el manejo de conocimiento pueden aportar una base confiable y flexible para el desarrollo de plataformas de ingeniería concurrente. Este artículo presenta una introducción a los conceptos relacionados con CE, el papel que los agentes de software y el modelado de datos juegan en ella, y describe brevemente un caso de estudio

The perceived self-efficacy of teachers in the use of digital tools during the COVID-19 Pandemic: a comparative study between Spain and the United States

[EN] This study analyzed the use of fifteen groups of digital tools that 197 active teachers made during the sudden shift to remote instruction due to the COVID-19 quarantine orders placed by various health departments in Spain and the United States. The study also examined the impact that the use of digital tools had on teachers’ perceived self-efficacy. A quantitative research design was used, supported by an exploratory descriptive approach that materializes in the application of an online questionnaire during the spring of 2020. The results indicate that perceived self-efficacy differs from country of origin and is conditioned by sociodemographic variables such as the training received and type of center. It is noted that teachers in Spain prefer the use of Moodle or Escholarium over that of teachers in the United States that opted for Google Classroom as a primary platform for teaching online, and the frequency of use of digital tools analyzed does not guarantee that their implementation is effective.S

El Programa 3x1: De la filantropía transnacional al desarrollo local con enfoque transnacional

Como resultado de la creciente interdependencia económica, social, política y cultural entre México y los Estados Unidos en los últimos cien años, se han multiplicado los intercambios de todo tipo entre miles de comunidades de origen de los migrantes mexicanos y sus lugares de destino en la Unión Americana. El estudio económico, social, cultural y político de esta realidad se puede realizar de mejor manera usando la perspectiva transnacional que plantea como objeto de estudio central las ocupaciones y actividades que requieren de contactos sociales habituales y sostenidos a través de las fronteras nacionales para su ejecución. Para Portes, Guarnizo y Landolt (2003) lo que constituye un fenómeno en verdad original y, por tanto, justificable como nuevo tema de investigación es la gran intensidad de los intercambios, nuevas formas de transacción y multiplicidad de actividades que traspasan las fronteras nacionales y requieren de este movimiento geográfico para su éxito. De manera particular, las prácticas de filantropía transnacional que las organizaciones de migrantes mexicanas realizan desde Estados Unidos a favor de sus comunidades de origen desde los años sesenta del siglo anterior se ubican perfectamente como parte del objeto de estudio de la perspectiva transnacional antes señalada

Undecidability as solution to the problem of measurement: fundamental criterion for the production of events

In recent papers we put forth a new interpretation of quantum mechanics, colloquially known as ``the Montevideo interpretation''. This interpretation is based on taking into account fundamental limits that gravity imposes on the measurement process. As a consequence one has that situations develop where a reduction process is undecidable from an evolution operator. When such a situation is achieved, an event has taken place. In this paper we sharpen the definition of when and how events occur, more precisely we give sufficient conditions for the occurrence of events. We probe the new definition in an example. In particular we show that the concept of undecidability used is not ``FAPP'' (for all practical purposes), but fundamental.Comment: 10 pages, contributed to the Castagnino Festschrif