El uso de las analogías en la enseñanza de la física

El propósito de ésta investigación fue indagar la relación analógica que poseen los estudiantes y que ésta pueda contribuir con la enseñanza de la Física, a través del uso de las analogías, permitiendo relacionar los hechos sociales cotidianos del comportamiento humano y los conceptos físicos. Esto permitirá un acercamiento de los estudiantes hacia el aprendizaje de la Física. La investigación de campo muestra la posibilidad de desarrollar estrategias didácticas con el uso de las analogías y la riqueza simbólica que proporcionan en las clases de Física para reforzar algunos hechos o situaciones de la temática desarrollada a objeto de lograr que los estudiantes entiendan los conceptos físicos y reforzar situaciones o descripciones complejas o abstractas

El uso de las analogías en la enseñanza de la física

El propósito de ésta investigación fue indagar la relación analógica que poseen los estudiantes y que ésta pueda contribuir con la enseñanza de la Física, a través del uso de las analogías, permitiendo relacionar los hechos sociales cotidianos del comportamiento humano y los conceptos físicos. Esto permitirá un acercamiento de los estudiantes hacia el aprendizaje de la Física. La investigación de campo muestra la posibilidad de desarrollar estrategias didácticas con el uso de las analogías y la riqueza simbólica que proporcionan en las clases de Física para reforzar algunos hechos o situaciones de la temática desarrollada a objeto de lograr que los estudiantes entiendan los conceptos físicos y reforzar situaciones o descripciones complejas o abstractas

Superconducting atomic contacts inductively coupled to a microwave resonator

We describe and characterize a microwave setup to probe the Andreev levels of a superconducting atomic contact. The contact is part of a superconducting loop inductively coupled to a superconducting coplanar resonator. By monitoring the resonator reflection coefficient close to its resonance frequency as a function of both flux through the loop and frequency of a second tone we perform spectroscopy of the transition between two Andreev levels of highly transmitting channels of the contact. The results indicate how to perform coherent manipulation of these states.Comment: 14 pages, 10 figures, to appear in special issue on break-junctions in JOPC

Computing FO-Rewritings in EL in Practice: from Atomic to Conjunctive Queries

A prominent approach to implementing ontology-mediated queries (OMQs) is to rewrite into a first-order query, which is then executed using a conventional SQL database system. We consider the case where the ontology is formulated in the description logic EL and the actual query is a conjunctive query and show that rewritings of such OMQs can be efficiently computed in practice, in a sound and complete way. Our approach combines a reduction with a decomposed backwards chaining algorithm for OMQs that are based on the simpler atomic queries, also illuminating the relationship between first-order rewritings of OMQs based on conjunctive and on atomic queries. Experiments with real-world ontologies show promising results

On the succinctness of query rewriting over shallow ontologies

We investigate the succinctness problem for conjunctive query rewritings over OWL2QL ontologies of depth 1 and 2 by means of hypergraph programs computing Boolean functions. Both positive and negative results are obtained. We show that, over ontologies of depth 1, conjunctive queries have polynomial-size nonrecursive datalog rewritings; tree-shaped queries have polynomial positive existential rewritings; however, in the worst case, positive existential rewritings can be superpolynomial. Over ontologies of depth 2, positive existential and nonrecursive datalog rewritings of conjunctive queries can suffer an exponential blowup, while first-order rewritings can be superpolynomial unless NP �is included in P/poly. We also analyse rewritings of tree-shaped queries over arbitrary ontologies and note that query entailment for such queries is fixed-parameter tractable

Eigenfunction Statistics on Quantum Graphs

We investigate the spatial statistics of the energy eigenfunctions on large quantum graphs. It has previously been conjectured that these should be described by a Gaussian Random Wave Model, by analogy with quantum chaotic systems, for which such a model was proposed by Berry in 1977. The autocorrelation functions we calculate for an individual quantum graph exhibit a universal component, which completely determines a Gaussian Random Wave Model, and a system-dependent deviation. This deviation depends on the graph only through its underlying classical dynamics. Classical criteria for quantum universality to be met asymptotically in the large graph limit (i.e. for the non-universal deviation to vanish) are then extracted. We use an exact field theoretic expression in terms of a variant of a supersymmetric sigma model. A saddle-point analysis of this expression leads to the estimates. In particular, intensity correlations are used to discuss the possible equidistribution of the energy eigenfunctions in the large graph limit. When equidistribution is asymptotically realized, our theory predicts a rate of convergence that is a significant refinement of previous estimates. The universal and system-dependent components of intensity correlation functions are recovered by means of an exact trace formula which we analyse in the diagonal approximation, drawing in this way a parallel between the field theory and semiclassics. Our results provide the first instance where an asymptotic Gaussian Random Wave Model has been established microscopically for eigenfunctions in a system with no disorder.Comment: 59 pages, 3 figure

Advanced oxidation processes with Uv-H2O2 for nitrification and decolorization of dyehouse wastewater

In this work, a UV/H2O2 system was evaluated using an experimental design 2 level I-optimal response surface design to analyze the effect of temperature, pH, UV lamp power (W), and H2O2 concentration on dye load removal and nitrification from industrial cleaning wastewater. Results showed that the optimum conditions were 80 °C, pH 4, PW-UV 60 W, and H2O2 3.1 Mol*L-1. Removal percentages of 45% for COD, 47.5% color, 87% Fe, 82% Cr and 91% ammonium oxidation to nitrate were achieved. It can be concluded that the effluents treated by this process could be promising for reuse and exploitation in biotechnological tools through microalgae and cyanobacteria

IRGC and Iranian Soft and Hard Power Influence Within the Middle East

The IRGC, or the Iranian Revolutionary Guard Corps, and Iran have utilized soft power to increase their influence within the Middle East. By using military superiority; ideological influence; and trade, both the Iran and the IRGC established dependency between themselves and patron states. Of these patron states, the research focuses on Iraq; Syria; and Yemen, and how Iran and the IRGC affect them through soft power. This research suggests that Iran and the IRGC is using the disability of the aforementioned states to increase their own influence by making them dependent on Iranian military supplies; cultural indoctrination to align with Iranian ideology; and economic dependent on Iran. As Iran\u27s influence grows within these states, its power in the Middle East grows and becomes a security risk for Saudi Arabia; Israel; and any other regime that does not have its interests align with the Iranian regime

Stretched exponential relaxation for growing interfaces in quenched disordered media

We study the relaxation for growing interfaces in quenched disordered media. We use a directed percolation depinning model introduced by Tang and Leschhorn for 1+1-dimensions. We define the two-time autocorrelation function of the interface height C(t',t) and its Fourier transform. These functions depend on the difference of times t-t' for long enough times, this is the steady-state regime. We find a two-step relaxation decay in this regime. The long time tail can be fitted by a stretched exponential relaxation function. The relaxation time is proportional to the characteristic distance of the clusters of pinning cells in the direction parallel to the interface and it diverges as a power law. The two-step relaxation is lost at a given wave length of the Fourier transform, which is proportional to the characteristic distance of the clusters of pinning cells in the direction perpendicular to the interface. The stretched exponential relaxation is caused by the existence of clusters of pinning cells and it is a direct consequence of the quenched noise.Comment: 4 pages and 5 figures. Submitted (5/2002) to Phys. Rev.