An Empirical Study of Real-World SPARQL Queries

Understanding how users tailor their SPARQL queries is crucial when designing query evaluation engines or fine-tuning RDF stores with performance in mind. In this paper we analyze 3 million real-world SPARQL queries extracted from logs of the DBPedia and SWDF public endpoints. We aim at finding which are the most used language elements both from syntactical and structural perspectives, paying special attention to triple patterns and joins, since they are indeed some of the most expensive SPARQL operations at evaluation phase. We have determined that most of the queries are simple and include few triple patterns and joins, being Subject-Subject, Subject-Object and Object-Object the most common join types. The graph patterns are usually star-shaped and despite triple pattern chains exist, they are generally short.Comment: 1st International Workshop on Usage Analysis and the Web of Data (USEWOD2011) in the 20th International World Wide Web Conference (WWW2011), Hyderabad, India, March 28th, 201

Kinematics of Herbig-Haro Objects and Jets in the Orion Nebula

We have surveyed the inner 5' of the Orion Nebula by means of Halpha and [NII] Fabry-Perot imaging spectroscopy to present a kinematical study of the Herbig-Haro objects in the nebula. The objects studied in this work are HH 202, 203, 204, 529, 269 and other associated features. For HH 202 we find new features that, because of their high velocities (up to 100 km/seg) indicate the presence of an outflow that probably is a HH flow not catalogued previously. HH 202 could be only a part of this larger outflow. Large internal motions are found in the fainter regions of HH 203-204, as well as evidence of transverse density gradients that could account for the asymmetry in the brightness distribution of HH 204. We report for the first time a high blueshifted velocity (-118 km/seg) associated with HH 204, and show that the apex of HH 204 is indeed the zone of maximum velocity, in agreement with bow shock models. We also studied the radial velocity field of HH 269 finding features associated with the HH object. From our studies, we find kinematic evidence that suggests that HH 203-204 and HH 202 are part of a big (aprox. 0.55 pc) bipolar HH outflow.Comment: 24 pages, 10 figures (in three jpg files). To be Published in Astronomical Journa

Estudio de las dificultades de atención asociadas a las estrategias de autorregulación en alumnos de secundaria

[Resumen] Desde la conceptuación realizada por Liebert y Morris (1967) de la ansiedad ante la evaluación, se ha generado una importante cantidad de estudios. Los esfuerzos investigadores se han dirigido principalmente a determinar la influencia de la ansiedad ante la evaluación y sus componentes (preocupación y emIocionalidad) en la ejecución de diversas tareas y al conocimiento de los procesos cognitivos mediadores. El presente estudio pretende constatar la existencia de los efectos causales producidos por la ansiedad ante la evaluación y sus componentes en la ejecución de una tarea de atención. Al mismo tiempo, nos interesamos por la naturaleza de las estrategias cognitivas de autorregulación (facilitadoras vs. interferentes) generadas por los estudiantes durante la ejecución de dicha tarea. Los resultados demostraron la existencia de diferencias significativas en atención entre sujetos altos y bajos en preocupación. En relación con el componente enl0cional las diferencias no resultaron significativas. También aparecieron diferencias significativas en cuanto a la naturaleza de las estrategias cognitivas de autorregulación utilizadas por los sujetos. Del mismo modo, se observaron patrones de pensamiento diferentes entre alumnos de alto y bajo rendimiento en atención, produciendo los primeros lnás pensamientos de interferencia que los segundos. Por último, se constató que la preocupación frente a lo emocional, genera una mayor cantidad de estrategias que interfieren.[Abstract] Since the conceptualization realized by Liebert and Morris (1967) about the anxiety test (in evaluation situations), it has been generated an important amount ofresearches. The investigating efforts have been adressed, mainly, to determine the relative impact ofthe evaluation anxiety and its components (worry and emotionality) about the fuIfilment of several taks and about the knowledge of the mediating cognitive processes. This research sougth to confirm the existence of the differential causal effects from the evaluation anxiety and its components in the fulfilment of an attentional taks, and the nature of the cognitive strategies (facilitating and interfering) generated by students, during the fulfiment of the task. The results proved the existence of important differences only among students who had a high and low worry, not appearing any significance for the emotionality. On the other hand, important differences appeared in the nature of the cognitive responses, as wel1 as, pattems of differential responses for the high and low subjets, generating, the high ones lnore interfering thoughts than the low ones. Finally, it was confirmed that the worry, in contrast with the emotionality, is a generator of higher number of interfering strategies

Topological Field Theories and Duality

Topologically non trivial effects appearing in the discussion of duality transformations in higher genus manifolds are discussed in a simple example, and their relation with the properties of Topological Field Theories is established.Comment: 7 pages, Late

Microencapsulation Yield Assessment Using TGA

In this study, microcapsules containing different contents of different kinds of fragrances and with a regular spherical shape, 2,0–8,0 µm diameter, were synthesized in various core:shell ratios. Mint and cuir fragrances were successfully encapsulated in poly(urea-formaldehyde) (PUF) shell via in-situ polymerization. This was confirmed by optical microscope, scanning electron microscope (SEM) and Fourier transform infrared spectroscopy (FTIR) studies. By observation from thermogravimetric analysis (TGA), it was found a relation between thermal gravimetric curves and the amount of fragrance encapsulated, which was later contrasted by ultraviolet-visible spectroscopy. In this way, comparatively, the yield percentage values can be quantitatively defined with a sufficient degree of accuracy by TGA methodPostprint (author's final draft

Theory of Self- vs. Externally-Regulated LearningTM: Fundamentals, Evidence, and Applicability

The Theory of Self- vs. Externally-Regulated LearningTM has integrated the variables of SRL theory, the DEDEPRO model, and the 3P model. This new Theory has proposed: (a) in general, the importance of the cyclical model of individual self-regulation (SR) and of external regulation stemming from the context (ER), as two different and complementary variables, both in combination and in interaction; (b) specifically, in the teaching-learning context, the relevance of different types of combinations between levels of self-regulation (SR) and of external regulation (ER) in the prediction of self-regulated learning (SRL), and of cognitive-emotional achievement. This review analyzes the assumptions, conceptual elements, empirical evidence, benefits and limitations of SRL vs. ERL Theory. Finally, professional fields of application and future lines of research are suggested